ALBERT

Description: 〈p〉Publication date: 1 February 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Water Research, Volume 149〈/p〉 〈p〉Author(s): M. Aybar, P. Perez-Calleja, M. Li, J.P. Pavissich, R. Nerenberg〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The membrane-aerated biofilm reactor (MABR) is a novel wastewater treatment technology based on oxygen-supplying membranes. The counter diffusion of oxygen and electron donors in MABRs leads to unique behavior, and we hypothesized it also could impact predation. We used optical coherence tomography (OCT), microsensor analyses, and mathematical modeling to investigate predation in membrane-aerated biofilms (MABs). When protozoa were excluded from the inoculum, the MAB's OCT-observable void fraction was around 5%. When protozoa were included, the void fraction grew to nearly 50%, with large, continuous voids at the base of the biofilm. Real-time OCT imaging showed highly motile protozoa in the voids. MABs with protozoa and a high bulk COD (270 mg/L) only had 4% void fraction. DNA sequencing revealed a high relative abundance of amoeba in both high and low-COD MABs. Flagellates were only abundant in the low-COD MAB. Modeling also suggested a relationship between substrate concentrations, diffusion mode (co- or counter-diffusion), and biofilm void fraction. Results suggest that amoeba proliferate in the biofilm interior, especially in the aerobic zones. Voids form once COD limitation at the base of MABs allows predation rates to exceed microbial growth rates. Once formed, the voids provide a niche for motile protozoa, which expand the voids into a large, continuous gap. This increases the potential for biofilm sloughing, and may have detrimental effects on slow-growing, aerobic microorganisms such as nitrifying bacteria.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0043135418309011-fx1.jpg" width="453" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 1 February 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Water Research, Volume 149〈/p〉 〈p〉Author(s): C. Caicedo, K.-H. Rosenwinkel, M. Exner, W. Verstraete, R. Suchenwirth, P. Hartemann, R. Nogueira〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Wastewater treatment plants (WWTPs) have been identified as confirmed but until today underestimated sources of 〈em〉Legionella,〈/em〉 playing an important role in local and community cases and outbreaks of Legionnaires’ disease. In general, aerobic biological systems provide an optimum environment for the growth of 〈em〉Legionella〈/em〉 due to high organic nitrogen and oxygen concentrations, ideal temperatures and the presence of protozoa. However, few studies have investigated the occurrence of 〈em〉Legionella〈/em〉 in WWTPs, and many questions in regards to the interacting factors that promote the proliferation and persistence of 〈em〉Legionella〈/em〉 in these treatment systems are still unanswered. This critical review summarizes the current knowledge about 〈em〉Legionella〈/em〉 in municipal and industrial WWTPs, the conditions that might support their growth, as well as control strategies that have been applied. Furthermore, an overview of current quantification methods, guidelines and health risks associated with 〈em〉Legionella〈/em〉 in reclaimed wastewater is also discussed in depth. A better understanding of the conditions promoting the occurrence of 〈em〉Legionella〈/em〉 in WWTPs will contribute to the development of improved wastewater treatment technologies and/or innovative mitigation approaches to minimize future 〈em〉Legionella〈/em〉 outbreaks.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0043135418308972-fx1.jpg" width="284" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 1 February 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Water Research, Volume 149〈/p〉 〈p〉Author(s): Sanghun Park, Taewoo Nam, Jeongyeop You, Eun-Sik Kim, Ilhwan Choi, Jongkwan Park, Kyung Hwa Cho〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Isolating dissolved organic matter (DOM) is a preliminary step that improves the accuracy of its characterization. In this study, DOM in brackish water was clearly separated and evaluated by multiple characterization analyses. The sample was divided into three fractions by preparative high-performance liquid chromatography (preparative HPLC) according to molecular size. The homogeneity of each fraction was estimated by analytical size exclusion chromatography (SEC) and fluorescence excitation-emission matrix (FEEM). Pyrolysis gas chromatography-mass spectrometry (Py-GC/MS) and liquid chromatography-organic carbon detection (LC-OCD) were used to characterize the physicochemical properties of each fraction. Py-GC/MS revealed that Fraction 1 consisted of evenly distributed organic matter in order polysaccharides, proteins, polyhydroxy aromatics, lignins, and lipids. However, Fraction 2 was primarily composed of dominant lipids and low portion of proteins, and Fraction 3 was composed predominantly of lignins and lipids. The LC-OCD results showed that Fractions 1 and 2 had similar organic carbon (OC) compositions: a humic substance (ca. 37%), building blocks (ca. 10%), and neutrals (ca. 37%), whereas Fraction 3 contained a high proportion of neutrals (62%). In the fouling experiments, the distinct DOM characteristics in each fraction resulted in different declining flux behaviors, ranked as: Fraction 2 〉 Fraction 1 〉 Fraction 3.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0043135418308960-fx1.jpg" width="500" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 1 January 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Water Research, Volume 148〈/p〉 〈p〉Author(s): Rui Luo, Miaoqing Li, Chaohai Wang, Ming Zhang, Muhammad Abdul Nasir Khan, Xiuyun Sun, Jinyou Shen, Weiqing Han, Lianjun Wang, Jiansheng Li〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The degradation of organic contaminants under high salinity condition is still a challenge for environmental remediation due to the inhibiting effect resulted from the side reactions between radicals and anions. Here, we demonstrate the non-radical oxidation process via peroxymonosulfate (PMS) activation by metal-free carbon catalyst for efficiently decomposing bisphenol A (BPA) in saline water. The nitrogen-doped graphitic carbon (NGC700) exhibits excellent catalytic activity for depredating BPA at acid and neutral pH. Based on the scavenger experiments and electron paramagnetic resonance (EPR) analyses, the mechanism of catalytic oxidation was elucidated as the non-radical pathway, and singlet oxygen was identified as the primary reactive species. Experiments on the influence of anions (5–500 mM) further show that the inhibiting effect was overcame due to the non-radical process. Interestingly, Cl〈sup〉−〈/sup〉 markedly facilitated the catalytic performance by generating HOCl in the catalytic process. The results highlight leveraging the non-radical pathway dominated by singlet oxygen to conquer the inhibitory effect of anions in NGC700/PMS system, which represents a crucial step towards environmental remediation under high salinity condition.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0043135418309047-fx1.jpg" width="385" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 25 January 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Applied Thermal Engineering, Volume 147〈/p〉 〈p〉Author(s): Jan Seiler, Franz Lanzerath, Christoph Jansen, André Bardow〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Efficient evaporation of water at low temperatures is challenging due to its low saturation pressure. As a consequence, the preferred evaporation by nucleate boiling can only be achieved at the cost of high superheats. However, low superheats can still lead to efficient evaporation by thin-film evaporation. In this work, we experimentally characterize the heat transfer for thin-film evaporation on coated copper tubes, which use capillary action to create a thin film on their surface. The overall heat transfer through the tubes is determined at all filling levels for evaporator inlet temperatures of 10, 15 and 20 °C with varied driving force. Our experiments reveal that poor coatings suffer from dry-out at high driving forces whereas tubes with good coatings remain fully wetted even at high driving force. Furthermore, we show the impact of surface properties on thin-film evaporation: high porosity, surface extension and roughness promote the creation of a thin film on the tube. Thereby, the heat transfer 〈em〉UA〈/em〉-value is increased up to a factor of 10.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 25 January 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Applied Thermal Engineering, Volume 147〈/p〉 〈p〉Author(s): Jianxin Xu, Qingtai Xiao, Zhihan Lv, Junwei Huang, Ruoxiu Xiao, Jianxin Pan, Hua Wang〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉We propose a new method to measure uniformity of gas-liquid mixing in a direct-contact heat exchanger by moment balance and image analysis. A mapping technique is developed to project the pixels distribution from binary image to 3D domain. We present a rigorous theoretical base of the applied method based on moments and equilibrium theory. An inclination angle with direction is derived to characterize the imbalanced structure caused by heterogeneity of mass distribution, which is used to quantify the global uniformity of spatial distribution of mixtures in any irregular area. A characteristic curve obtained by local inclination angles can be used to test the homogeneous, heterogeneous and pseudo-homogeneous mixtures, leading to a useful parameter to quantify the mixing effects. The uniformity obtained by similar patterns are compared with existing methods. The experimental results show a good fitting curve between mixing effects and heat transfer performance. This test could also be applied for studying a variety of multiphase mixing problems in which assessment of uniformity is required.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 1 February 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Water Research, Volume 149〈/p〉 〈p〉Author(s): Jianzhong Ma, Huaxi Zhou, Shuwen Yan, Weihua Song〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Superoxide ion (O〈sub〉2〈/sub〉〈sup〉•−〈/sup〉) is one of the short lived reactive oxygen species (ROS) formed in aquatic environments. The reactions of O〈sub〉2〈/sub〉〈sup〉•−〈/sup〉 with the model dissolved organic matter (DOM) were studied using a chemiluminescent analysis method under relevant environmental conditions. The reaction of O〈sub〉2〈/sub〉〈sup〉•−〈/sup〉 with DOM produced reduced DOM (DOM〈sup〉•−〈/sup〉) by fast one-electron-transfer in the initial stage. This process resulted an initial “loss” in the O〈sub〉2〈/sub〉〈sup〉•−〈/sup〉 decay kinetics. DOM〈sup〉•−〈/sup〉 is unstable which will continue react with O〈sub〉2〈/sub〉〈sup〉•−〈/sup〉 generating H〈sub〉2〈/sub〉O〈sub〉2〈/sub〉 to complete a catalytic dismutation cycle. Based on analyzing the observed pseudo-first order O〈sub〉2〈/sub〉〈sup〉•−〈/sup〉 decay rates (〈em〉k〈/em〉〈sub〉pseudo〈/sub〉), the quasi-steady-state concentration of DOM〈sup〉•−〈/sup〉 is found to be equal to the initial loss of O〈sub〉2〈/sub〉〈sup〉•−〈/sup〉. Thus, the rate constant for DOM〈sup〉•−〈/sup〉 with HO〈sub〉2〈/sub〉〈sup〉•〈/sup〉/O〈sub〉2〈/sub〉〈sup〉•−〈/sup〉 is derived to be (1.1–1.9) × 10〈sup〉6〈/sup〉 M〈sup〉−1〈/sup〉 s〈sup〉−1〈/sup〉 in the temperature range of 7.8–41.4 °C. Meanwhile, the apparent rate constant for DOM with O〈sub〉2〈/sub〉〈sup〉•−〈/sup〉 in a flow cell during a short time (2.25 s) is measured as (1.5–3.3) × 10〈sup〉3〈/sup〉 M〈sub〉C〈/sub〉〈sup〉−1〈/sup〉 s〈sup〉−1〈/sup〉 in the temperature range of 8.2–38.6 °C. These temperature dependent O〈sub〉2〈/sub〉〈sup〉•−〈/sup〉 reaction rate constants present an apparent activation energy of (19.6 ± 2.9) kJ mol〈sub〉C〈/sub〉〈sup〉−1〈/sup〉 for DOM, while that of DOM〈sup〉•−〈/sup〉 (12.5 ± 3.5 kJ mol〈sup〉−1〈/sup〉) is lower. For the pseudo-first order decay rate of O〈sub〉2〈/sub〉〈sup〉•−〈/sup〉, the catalyzed-dismutation by metal components ranges from 13 to 23%; the contribution by aromatic ketones of DOM is estimated to be 10–13% by using NaBH〈sub〉4〈/sub〉 reduction method. The residual contribution might mainly occur at the quinone-like groups, which contributed 64%–77% to the total dismutation. The pH effects on the apparent catalytic rate constants dominate the reaction of O〈sub〉2〈/sub〉〈sup〉•−〈/sup〉 with DOM. The present work suggests that DOM is an important sink for O〈sub〉2〈/sub〉〈sup〉•−〈/sup〉 in aquatic environments. Furthermore, we proposed that the reaction of O〈sub〉2〈/sub〉〈sup〉•−〈/sup〉 with DOM could be a potential source of DOM〈sup〉•−〈/sup〉 in natural water.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0043135418308984-fx1.jpg" width="267" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 25 January 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Applied Thermal Engineering, Volume 147〈/p〉 〈p〉Author(s): Olga Arsenyeva, Julian Tran, Mark Piper, Eugeny Kenig〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Pillow-plate heat exchangers (PPHEs) represent a novel equipment type. For their application in industry, reliable preliminary design techniques are required. In this article, the existing methods for heat exchangers design are analysed and the approach for selecting the PPHE design with minimal heat transfer area is proposed. It is based on the mathematical model of thermal and hydraulic PPHE behaviour, in which the overall heat transfer coefficient and pressure drop in PPHEs are expressed through the fluid velocity. The estimation of fluid velocities in PPHE channels is based on the condition that the predefined allowable pressure drop is fully exploited. Two case studies for water heating and crude oil preheat train operating conditions are discussed, in which the flowrates of the fluids on the hot and cold sides differ significantly. The PPHE design with minimal heat transfer area for the considered case studies is presented, with specified pillow-plate geometry parameters and distance between pillow-plate panels. The resulting pressure drops and velocities in PPHEs channels as well as the obtained heat transfer surface areas are compared with existing data for chevron-type plate heat exchangers (PHEs) designed for the same operating conditions. This comparison shows that PPHEs have higher velocities in channels, longer plates and lower heat transfer area. It can be concluded that PPHEs can be successfully used for operating conditions, under which the flow rates for hot and cold fluid are significantly different and the application of chevron-type PHEs with single-pass arrangement is complicated.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 1 January 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Water Research, Volume 148〈/p〉 〈p〉Author(s): Stefano Bonaglia, Robert Rämö, Ugo Marzocchi, Léonie Le Bouille, Martine Leermakers, Francisco J.A. Nascimento, Jonas S. Gunnarsson〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Sediment capping with activated carbon (AC) is an effective technique used in remediation of contaminated sediments, but the ecological effects on benthic microbial activity and meiofauna communities have been largely neglected. This study presents results from a 4-week experiment investigating the influence of two powdered AC materials (bituminous coal-based and coconut shell-derived) and one control material (clay) on biogeochemical processes and meiofauna in contaminated sediments. Capping with AC induced a 62–63% decrease in denitrification and a 66–87% decrease in dissimilatory nitrate reduction to ammonium (DNRA). Sediment porewater pH increased from 7.1 to 9.0 and 9.7 after addition of bituminous AC and biomass-derived AC, respectively. High pH (〉8) persisted for at least two weeks in the bituminous AC and for at least 24 days in the coconut based AC, while capping with clay had no effect on pH. We observed a strong impact (nitrate fluxes being halved in presence of AC) on nitrification activity as nitrifiers are sensitive to high pH. This partly explains the significant decrease in nitrate reduction rates since denitrification was almost entirely coupled to nitrification. Total benthic metabolism estimated by sediment oxygen uptake was reduced by 30 and 43% in presence of bituminous coal-based AC and coconut shell-derived AC, respectively. Meiofauna abundances decreased by 60–62% in the AC treatments. Taken together, these observations suggest that AC amendments deplete natural organic carbon, intended as food, to heterotrophic benthic communities. Phosphate efflux was 91% lower in presence of bituminous AC compared to untreated sediment probably due to its content of aluminum (Al) oxides, which have high affinity for phosphate. This study demonstrates that capping with powdered AC produces significant effects on benthic biogeochemical fluxes, microbial processes and meiofauna abundances, which are likely due to an increase in porewater pH and to the sequestration of natural, sedimentary organic matter by AC particles.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S004313541830900X-fx1.jpg" width="500" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 1 January 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Water Research, Volume 148〈/p〉 〈p〉Author(s): Zhiqiang Dong, Wen Zhang, Yuping Qiu, Zhenglong Yang, Junliang Wang, Yidi Zhang〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Nanoplastics (NPs) have been identified as newly emerging particulate contaminants. In marine environments, the interaction between NPs and other engineered nanoparticles remains unknown. This study investigated the cotransport of NPs with fullerene (C〈sub〉60〈/sub〉) in seawater-saturated columns packed with natural sand as affected by the mass concentration ratio of NPs/C〈sub〉60〈/sub〉 and the hydrochemical characteristics. In seawater with 35 practical salinity units (PSU), NPs could remarkably enhance C〈sub〉60〈/sub〉 dispersion with a NPs/C〈sub〉60〈/sub〉 ratio of 1. NPs behaved as a vehicle to facilitate C〈sub〉60〈/sub〉 transport by decreasing colloidal ζ-potential and forming stable primary heteroaggregates. As the NPs/C〈sub〉60〈/sub〉 ratio decreased to 1/3, NPs mobility was progressively restrained because of the formation of large secondary aggregates. When the ratio continuously decreased to 1/10, the stability and transport of colloids were governed by C〈sub〉60〈/sub〉 rather than NPs. Under this condition, the transport trend of binary suspensions was similar to that of single C〈sub〉60〈/sub〉 suspension, which was characterized by a ripening phenomenon. Seawater salinity is another key factor affecting the stability and associated transport of NPs and C〈sub〉60〈/sub〉. In seawater with 3.5 PSU, NPs and C〈sub〉60〈/sub〉 (1:1) in binary suspension exhibited colloidal dispersion, which was driven by a high-energy barrier. Thus, the profiles of the cotransport and retention of NPs/C〈sub〉60〈/sub〉 resembled those of single NPs suspension. This work demonstrated that the cotransport of NPs/C〈sub〉60〈/sub〉 strongly depended on their mass concentration ratios and seawater salinity.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0043135418308741-fx1.jpg" width="453" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 25 January 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Applied Thermal Engineering, Volume 147〈/p〉 〈p〉Author(s): Nidhi, K.A. Subramanian〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The present experimental investigation deals with the study of the effect of oxygen enriched intake air on performance, emission and combustion characteristics of a methanol (M100) fuelled spark ignition engine. The oxygen in the intake air of the engine fuelled with methanol was enriched from 23% (by mass) with base oxygen to 26.5%, 38.7% and 60.4%. The brake thermal efficiency increased drastically with methanol with 38.7% and 60.4% enriched air by 9.9% and 20.5% respectively. The peak pressure and cumulative heat release with the highest enriched air (60.4%) are higher about 2 and 1.27 times than base oxygen percentage (23% by mass). The ignition delay and combustion duration decreased by 35.24% and 57.8% respectively. Carbon monoxide (CO) and hydrocarbon (HC) emissions with the highest enriched air decreased substantially by 48.59% and 30.9%. However, nitrogen oxides (NO〈sub〉x〈/sub〉) emission increased drastically by 112.2% with 38.7% of oxygen but it decreased by 31.5% with 60.4% oxygen enriched air which is lower than base oxygen. A notable conclusion emerged from this study is that a methanol fuelled engine with the oxygen enriched air (60.4%) could emit very lower emissions (CO, HC, NO〈sub〉x〈/sub〉) along with improved thermal efficiency compared to base oxygen (23% by mass).〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 25 January 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Applied Thermal Engineering, Volume 147〈/p〉 〈p〉Author(s): Manuel Colera, Ángel Soria, Javier Ballester〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉In this work we present a numerical scheme for the steady-state thermodynamic analysis of gas turbine engines. As usual in the literature, it is based on modelling the gas turbine as a set of independent components connected through nodes, thus giving the user great flexibility to modify the gas turbine’s model and to define and include new components. Additionally, the proposed method provides the same flexibility for the inclusion of new gas properties calculators and nonlinear equations solvers. The simulator also allows identifying the characteristic parameters of the different components of the gas turbine –such as the compressor’s nominal pressure ratio and efficiency– from a batch of operation data. The latter task is accomplished by means of a systematic and computationally economic procedure which allows that the parameters identification be performed component-by-component and does not require any full gas turbine simulations. The scheme has been formulated so that it exploits the full capabilities of today’s computers and mathematical techniques –such as sparse matrix solvers and quasi-Newton methods for sparse jacobians– but, at the same time, remains simple enough to be self-implemented by the interested researchers with the aid of general-purpose mathematical computing software such as Matlab. The simulator has been applied to predict the performance of a real gas turbine, obtaining excellent results.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 1 February 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Water Research, Volume 149〈/p〉 〈p〉Author(s): Peng Wei, Robert F. Mudde, Wim Uijttewaal, Henri Spanjers, Jules B. van Lier, Merle de Kreuk〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉This study aimed to characterise the gas-liquid flow and mixing behaviour in a gas-mixed anaerobic digester by improving phase interaction modelling using Computational Fluid Dynamics (CFD). A 2D axisymmetric model validated with experimental data was set up using an Eulerian-Eulerian method. Uncertainty factors, including bubble size, phase interaction forces and liquid rheology were found to significantly influence the flow field. A more reliable and complete validation was obtained by critical comparison and assessment of the referred experimental data, compared to the models reported in other studies. Additionally, justifiable corrections and predictions in detail were obtained. Mixing was evaluated by trajectory tracking of a large number of particles based on an Euler-Lagrange method. The mixing performance approximated to a laminar-flow reactor (LFR) that distinctly deviated from expected continuous stirred tank reactor (CSTR) design, indicating limited enhancement from the applied gas-sparging strategy in the studied digester. The study shows the importance of a proper phase-interaction description for a reliable hydrodynamic characterisation and mixing evaluation in gas-mixed digesters. Validations, bend to experimental data without a critical assessment, may lead to an inaccurate model for further scaled-up applications.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0043135418308947-fx1.jpg" width="131" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 1 January 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Water Research, Volume 148〈/p〉 〈p〉Author(s): Santo Fabio Corsino, Marco Capodici, Francesca Di Pippo, Valter Tandoi, Michele Torregrossa〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉 〈p〉Biological nutrient removal performances and kinetics of autochthonous marine biomass in forms of activated sludge and aerobic granular sludge were investigated under different salinity and sludge retention time (SRT). Both the biomasses, cultivated from a fish-canning wastewater, were subjected to stepwise increases in salinity (+2 gNaCl L〈sup〉−1〈/sup〉), from 30 gNaCl L〈sup〉−1〈/sup〉 up to 50 gNaCl L〈sup〉−1〈/sup〉 with the aim to evaluate the maximum potential in withstanding salinity by the autochthonous marine biomass. Microbial marine species belonging to the genus of Cryomorphaceae and of Rhodobacteraceae were found dominant in both the systems at the maximum salinity tested (50 gNaCl L〈sup〉−1〈/sup〉). The organic carbon was removed with a yield of approximately 98%, irrespective of the salinity. Similarly, nitrogen removal occurred via nitritation-denitritation and was not affected by salinity. The ammonium utilization rate and the nitrite utilization rate were approximately of 3.60 mgNH〈sub〉4〈/sub〉-N gVSS〈sup〉−1〈/sup〉h〈sup〉−1〈/sup〉 and 10.0 mgNO〈sub〉2〈/sub〉-N gVSS〈sup〉−1〈/sup〉h〈sup〉−1〈/sup〉, respectively, indicating a high activity of nitrifying and denitrifying bacteria. The granulation process did not provide significant improvements in the nutrients removal process likely due to the stepwise salinity increase strategy. Biomass activity and performances resulted affected by long SRT (27 days) due to salt accumulation within the activated sludge flocs and granules. In contrast, a lower SRT (14 days) favoured the discharge of the granules and flocs with higher inert content, thereby enhancing the biomass renewing.〈/p〉 〈p〉The obtained results demonstrated that the use of autochthonous-halophilic bacteria represents a valuable solution for the treatment of high-strength carbon and nitrogen saline wastewater in a wide range of salinity. Besides, the stepwise increase in salinity and the operation at low SRT enabled high metabolic activity and to avoid excessive accumulation of salt within the biomass aggregates, limiting their physical destructuration due to the increase in loosely-bound exopolymers.〈/p〉 〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0043135418309035-fx1.jpg" width="412" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 1 January 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Water Research, Volume 148〈/p〉 〈p〉Author(s): Glen Andrew de Vera, Chance Lauderdale, Christina L. Alito, Jennifer Hooper, Eric C. Wert〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The combination of biological growth and particle loading can adversely affect hydraulic performance in drinking water biofilters. In this study, upstream oxidant addition was used to distribute biologically-derived filter clogging in granular activated carbon (GAC) biofilters. Oxidant penetration was assessed during pilot-scale operation and backwashing of dual media (GAC/sand) and multimedia (GAC/anthracite/sand) biofilters. Influent chlorine (HOCl), monochloramine (NH〈sub〉2〈/sub〉Cl), and hydrogen peroxide (H〈sub〉2〈/sub〉O〈sub〉2〈/sub〉) residuals were optimized to react with the GAC surface in the upper portion of the filter media bed (depth 〈 0.5 m) to attenuate biomass development. As the oxidant residual was quenched by surface-mediated reaction with the filter media, biomass growth was promoted deeper in the filter bed (depth 〉 0.5 m). The oxidant-induced effects on biomass and hydraulic performance were monitored through measurements of adenosine triphosphate (ATP) and head loss accumulation at different media depths. Addition of oxidants (e.g., 0.6 mg Cl〈sub〉2〈/sub〉/L HOCl) could decrease terminal head loss by 20% in dual media filters and 40% in multimedia filters. These hydraulic benefits were achieved without significantly affecting removal of assimilable organic carbon (AOC), total organic carbon (TOC), turbidity, and particle counts. Oxidant type, residual concentration, media type, media age, and media depth influenced the passage of oxidant residuals and distribution of filter biomass. When oxidants were added during backwashing, oxidant residual was quenched through the bed depth from a combination of reactions with GAC media and biofilm degradation. This attenuation of residual oxidant may prevent the oxidant residual from penetrating the entire bed depth, potentially compromising backwashing objectives.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0043135418309023-fx1.jpg" width="433" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 1 January 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Water Research, Volume 148〈/p〉 〈p〉Author(s): Shuo Wang, Kai Qian, Yin Zhu, Xuesong Yi, Guangsheng Zhang, Guocheng Du, Joo-Hwa Tay, Ji Li〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract:〈/h5〉 〈div〉〈p〉The work provides a method on the basis of flow cytometry to evaluate the performance of denitrification biofilm during the preservation, reactivation and pilot-scale operation process. The viable cell ratio of denitrification biofilm significantly reduced and further led to the decrease of denitrification capacity after long-term preservation for 5 months. Protein component in tightly bound extracellular polymeric substances (TB-EPS) could serve to enhance microbial adhesion and promote denitrification biofilm formation. With the significant correlation of viable cell ratio and microbial characteristics, 4 °C was more appropriate for preserving denitrification biofilm and conducive to maintain the relatively high denitrification capacity. A maximum denitrification rate of 5.80 gNO〈sub〉3〈/sub〉〈sup〉-〈/sup〉-N/m〈sup〉2〈/sup〉·d was obtained in pilot-scale anoxic-oxic (AO) process and 〈em〉Dechloromonas〈/em〉 became greater prevalence in denitrification suspended carriers. Furthermore, the enrichment of 〈em〉Pseudomonas〈/em〉, 〈em〉Parcubacteria〈/em〉, 〈em〉Acidovorax〈/em〉, 〈em〉Aquabacterium〈/em〉 and 〈em〉Unclassified_Flavobacteriaceae〈/em〉 enhanced biofilm formation and nutrient conservation. The significantly positive correlation between viable cell ratio and the ratio of nitrate reduction to COD consumption was discovered, and the indices of Chao, ACE, Shannon and Simpson of denitrification biofilm were positively correlated with viable cell ratio, meaning that flow cytometry analysis was reasonable and suitable to evaluate the performances of denitrification biofilm.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0043135418308753-fx1.jpg" width="473" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 1 January 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Water Research, Volume 148〈/p〉 〈p〉Author(s): Thomas B. Parr, Shreeram P. Inamdar, Matthew J. Miller〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Drinking water supplies are increasingly affected by overlapping anthropogenic global change processes. As a key currency of ecosystem function in aquatic ecosystems, dissolved organic carbon (DOC) concentration and composition is sensitive to many global change processes. However, DOC must also be removed to avoid the production of harmful disinfection byproducts as water is processed. Thus, understanding the effects of global change processes on the seasonal and long-term dynamics of DOC composition and concentration is critical for ensuring the sustainability of drinking water supplies. To understand these dynamics, we analyzed a novel 11-year time series of stream water DOC concentration and composition using Weighted Regressions on Time Discharge and Season (WRTDS) to understand the influences of co-occurring changes in climate and atmospheric deposition. We also discuss the implications for water supply provision and management. We found that, during our study period, overlapping global change processes in the watershed had the net effect of increasing the DOC aromaticity, as measured by SUVA〈sub〉254〈/sub〉, at moderate to high discharge levels during the late spring and early summer and the autumn and early winter. However, changes in DOC concentration were more dynamic and we observed both increasing and decreasing trends depending on season and hydrologic state. During summer, at low to moderate flow levels we observed a significant (p 〈 0.05) increase in DOC concentration. During autumn, at moderate to high flow levels we observed a significant (p 〈 0.05) decrease in DOC concentration and an increase in SUVA〈sub〉254〈/sub〉. For drinking water providers, our results suggest that close monitoring of source waters must be coupled with the development of plans accounting for season- and hydrology-specific long-term changes.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0043135418308686-fx1.jpg" width="276" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 1 January 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Water Research, Volume 148〈/p〉 〈p〉Author(s): Bin Liang, Jincai Ma, Weiwei Cai, Zhiling Li, Wenzong Liu, Mengyuan Qi, Youkang Zhao, Xiaodan Ma, Ye Deng, Aijie Wang, Jizhong Zhou〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Understanding the fate of overall antibiotic resistance genes (ARGs) during the biological treatment of antibiotic containing wastewater is a central issue for the water ecological safety assessment. Although the microbial electrode-respiration based biotransformation process could significantly detoxify some antibiotic contaminants, e.g. chloramphenicol (CAP), the response of CAP-reducing biocathode microbiome and resistome to continuous electrical stimulation, especially ARGs network interactions, are poorly understood. Here, using highthroughput functional gene array (GeoChip v4.6) and Illumina 16S rRNA gene MiSeq sequencing, the structure, composition, diversity and network interactions of CAP-reducing biocathode microbiome and resistome in response to continuous electrical stimulation were investigated. Our results indicate that the CAP bioelectroreduction process could significantly accelerate the elimination of antibacterial activity of CAP during CAP-containing wastewater treatment compared to the pure bioreduction process. Continuous electrical stimulation could obviously alter both the microbiome and resistome structures and consistently decrease the phylogenetic, functional and overall ARGs diversity and network complexity within the CAP-reducing biofilms. The relative abundances of overall ARGs and specific CAP resistance related major facilitator superfamily (MFS) transporter genes were significantly negatively correlated with the reduction efficiency of CAP to inactive antibacterial product AMCl (partially dechlorinated aromatic amine), which may reduce the ecological risk associated with the evolution of multidrug-resistant bacteria and ARGs during antibiotic-containing wastewater treatment process. This study offers new insights into the response of an antibiotic reducing biocathode resistome to continuous electrical stimulation and provides useful information on the assessment of overall ARGs risk for the bioelectrochemical treatment of antibiotic contaminants.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0043135418308765-fx1.jpg" width="426" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 1 February 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Water Research, Volume 149〈/p〉 〈p〉Author(s): Pengchao Xie, Li Zhang, Jinhui Chen, Jiaqi Ding, Ying Wan, Songlin Wang, Zongping Wang, Aijiao Zhou, Jun Ma〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Degradation of propranolol (PrP) by a combined zero-valent iron and sulfite system under simulated sunlight irradiation (ZVI/sulfite/photo) was investigated. Simulated sunlight irradiation enhanced the degradation of PrP by accelerating the decomposition of ferric sulfite complex as a result to producing sulfite radical (SO〈sub〉3〈/sub〉〈sup〉•−〈/sup〉). As bubbles would block the transport of photons in the reaction solution, mechanical aeration rather than purging air was suggested to sustain the essential dissolved oxygen. The degradation of PrP increased with the elevation of initial ZVI concentration from 0.05 to 0.5 mM, but decreased a little with further increasing ZVI concentration to 1.0 mM. The degradation of PrP raised from 68.5% to 98.7% while sulfite dose increased from 0.1 to 2.0 mM. High removal efficiencies were always achieved when the initial PrP concentration ranged from 10 to 40 μM. As HSO〈sub〉3〈/sub〉〈sup〉−〈/sup〉 which can efficiently complex Fe(II) and transfer Fe(III) to Fe(II) is the dominant species of sulfite at pH 4.0–6.0, the highest removal of PrP was achieved at pH 4.0–6.0. The presence of bicarbonate and humic acid significantly retarded the removal of PrP, while chloride ions could promote the removal of PrP to some extent. SO〈sub〉4〈/sub〉〈sup〉•−〈/sup〉, HO〈sup〉•〈/sup〉 and SO〈sub〉5〈/sub〉〈sup〉•−〈/sup〉 were suggested to account for PrP removal, while SO〈sub〉4〈/sub〉〈sup〉•−〈/sup〉 was evidenced to be the dominant radicals. Good reuse of ZVI in the system was also achieved as the removal of PrP kept higher than 80% after repeatedly used for 5 times. Possible degradation pathways of PrP in the ZVI/sulfite/photo system were accordingly proposed based on LC-MS and density functional theory calculation. The removal of amitriptyline, nitrobenzene, imipramine and methylparaben in the ZVI/sulfite/photo system was also evaluated. As a reducing agent, sulfite is expected to consume the possible formed bromine-containing intermediates as a result to inhibiting the formation of bromate, which is better than the activated persulfate system.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0043135418308959-fx1.jpg" width="357" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 1 February 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Water Research, Volume 149〈/p〉 〈p〉Author(s): Yu Miao, Nicholas W. Johnson, Phillip B. Gedalanga, David Adamson, Charles Newell, Shaily Mahendra〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Microbial community dynamics were characterized following combined oxidation and biodegradation treatment trains for mixtures of 1,4-dioxane and chlorinated volatile organic compounds (CVOCs) in laboratory microcosms. Bioremediation is generally inhibited by co-contaminate CVOCs; with only a few specific bacterial taxa reported to metabolize or cometabolize 1,4-dioxane being unaffected. Chemical oxidation by hydrogen peroxide (H〈sub〉2〈/sub〉O〈sub〉2〈/sub〉) as a non-selective treatment demonstrated 50–80% 1,4-dioxane removal regardless of the initial CVOC concentrations. Post-oxidation bioaugmentation with 1,4-dioxane metabolizer 〈em〉Pseudonocardia dioxanivorans〈/em〉 CB1190 removed the remaining 1,4-dioxane. The intrinsic microbial population, biodiversity, richness, and biomarker gene abundances decreased immediately after the brief oxidation phase, but recovery of cultivable microbiomes and a more diverse community were observed during the subsequent 9-week biodegradation phase. Results generated from the Illumina Miseq sequencing and bioinformatics analyses established that generally oxidative stress tolerant genus 〈em〉Ralstonia〈/em〉 was abundant after the oxidation step, and 〈em〉Cupriavidus〈/em〉, 〈em〉Pseudolabrys〈/em〉, 〈em〉Afipia〈/em〉, and 〈em〉Sphingomonas〈/em〉 were identified as dominant genera after aerobic incubation. Multidimensional analysis elucidated the separation of microbial populations as a function of time under all conditions, suggesting that temporal succession is a determining factor that is independent of 1,4-dioxane and CVOCs mixtures. Network analysis highlighted the potential interspecies competition or commensalism, and dynamics of microbiomes during the biodegradation phase, in line with the shifts of predominant genera and various developing directions during different steps of the treatment train. Collectively, this study demonstrated that chemical oxidation followed by bioaugmentation is effective for treating 1,4-dioxane, even in the presence of high levels of CVOC mixtures and residual peroxide, a disinfectant, and enhanced our understanding of microbial ecological impacts of the treatment train. These results will be valuable for predicting treatment synergies that lead to cost savings and improved remedial outcomes in short-term active remediation as well as long-term changes to the environmental microbial communities.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S004313541830873X-fx1.jpg" width="242" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 25 January 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Applied Thermal Engineering, Volume 147〈/p〉 〈p〉Author(s): Ehsan Taheran, Kourosh Javaherdeh〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Experimental study has been carried out to investigate the effects of inlet swirl generator on heat transfer and pressure drop of non-Newtonian drilling nanofluid under turbulent flow conditions. The equal volume mixture of water base silver nanofluid and a biological oil diluted by water was used as under test fluid. Thermal conductivity and rheological properties of novel drilling nanofluid were measured and an empirical model for thermal conductivity was proposed. Non-Newtonian power law coefficients of drilling nanofluid at three different temperatures were also presented. Nusselt number and friction factor for three different swirl generators twist angle (θ = 120 °C, 240 °C and 360 °C) were evaluated and thermo-hydraulic performance of non-Newtonian drilling nanofluid (〈math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si17.gif" overflow="scroll"〉〈mrow〉〈mi〉∅〈/mi〉〈mo〉=〈/mo〉〈mn〉0.1〈/mn〉〈mo〉%〈/mo〉〈mo〉,〈/mo〉〈mn〉0.5〈/mn〉〈mo〉%〈/mo〉〈mspace width="0.25em"〉〈/mspace〉〈mi〉a〈/mi〉〈mi〉n〈/mi〉〈mi〉d〈/mi〉〈mspace width="0.25em"〉〈/mspace〉〈mn〉1〈/mn〉〈mo〉%〈/mo〉〈/mrow〉〈/math〉) was calculated at different Reynolds numbers from 4,000 to 10,000. The obtained results stated that the flow behavior depends on the nanofluid concentration, swirl generators geometry and Reynolds number. According to the experimental data, Nusselt number increased up to 86% but enormous enhancement in friction factor (up to 370%) limited the maximum thermo-hydraulic performance augmentation to 35%.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 25 January 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Applied Thermal Engineering, Volume 147〈/p〉 〈p〉Author(s): Yiran Zheng, Yu Shi, Yunhui Huang〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉We propose a thermal management system for fast charging Li-ion battery pack combining liquid cooling and phase change material cooling. The main heat dissipating approach is liquid cooling, while composite phase change material wipes out the thermal-opaque area in the battery pack and provides relatively small amount of heat absorption. Alternated flow of coolant is required to guarantee temperature uniformity in the battery pack but is found detrimental to the systematic thermal dissipation. A method to address that issue, adding polyurethane adiabatic interlayers between cooling tubes, is proven to be an effective answer. Via analysing the heat transfer mechanism of the designed thermal management system, the influencing factors on its performance are found and a heat dissipation balancing coefficient is defined to quantify the temperature balancing performance of the system. The simulation for the system under an 8C rate charging condition is conducted, as well as compare tests concerning coolant flowing directions, coolant flowing speeds, filling materials, and the interlayers. Simulation results show that the system in question well controls the temperature of an 8C rate charging battery pack, with the maximum temperature at 38.69 °C and the temperature difference at 2.23 °C.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 25 January 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Applied Thermal Engineering, Volume 147〈/p〉 〈p〉Author(s): Eid S. Mohamed〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Exhaust heat from vehicle engines can be one of the promising heat sources to provide additional energy using thermoelectric generation (TEG). However, the objective of this study is to assess the exhaust heat recovery behavior by TEG, evaluation of diesel fuel consumption (DFC) and exhaust emissions. Thirty standard thermoelectric modules (TEMs) were mounted on the two sides (1 × 5) and lower side (4 × 5) arrangement of a light diesel vehicle exhaust channel. A detailed experimental work was carried out to study the performance behavior of TEG system with different engine speeds and over new European driving cycle (NEDC) using chassis dynamometer. Comparative analyses of the exhaust gases flow rate, DFC, exhaust emissions such as THC, CO, CO〈sub〉2〈/sub〉, and smoke emissions have been measured during NEDC with and without TEG actuation. Experimental results observed that the average value of TEG system efficiency is approximately 4.63% under the NEDC conditions. It also found that: by actuation the TEG system, the effectiveness of DFC percentage has been reduced by (1.46%–3.13%), lower exhaust gas emissions were found, too. The experimental result of output power is in good agreement with the theoretical result within 5.16% error at 1500 rpm.〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S1359431118301236-ga1.jpg" width="328" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 25 January 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Applied Thermal Engineering, Volume 147〈/p〉 〈p〉Author(s): Kun Tu, Qiang Wu, Haizhou Sun〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Owing to the limitation of the available land in China, among various ground source heat pump (GSHP) system configurations, the single-well circulation (SWC) coupled GSHP systems are being intended to provide heating and cooling for building in recent years, especially utilized in this area with suitable hydrogeological and thermogeological conditions. This is due to the fact that the SWC system could not only substantially provide shallow geothermal energy for space heating or cooling in small-scale applications, but also reduce the number of boreholes needed for large-scale geothermal applications. In this work, a mathematical model has been established to analysis the groundwater seepage of SWC system, and analytical solution of steady drawdown was derived. Meanwhile, a numerical model was constructed to evaluate the thermal performance by using SWC coupled GSHP systems. Numerical experiments were performed to observe the evolution of outlet temperature, the distribution of subsurface temperature field, and the long-term development of outlet temperature. It was found that the thermal effective radius (TER) of SWC system is much larger than that of ground-coupled heat pump (GCHP) systems. Also, the temperature field in vertical section caused by the operation of SWC system is funnel-shaped. In addition, the outlet temperature fluctuates annually, and it rather starts a long-term decaying process, until reaching a quasi-steady state after about 8–10 years.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 25 January 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Applied Thermal Engineering, Volume 147〈/p〉 〈p〉Author(s): Gang Wang, Gaosheng Wei, Chao Xu, Xing Ju, Yanping Yang, Xiaoze Du〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Different foam metals combined with paraffin and other materials were analyzed to determine their effective thermal conductivity and the macroscopic thermophysical properties of the composite materials. A W-P model composed of six tetrakaidecahedrons and two irregular dodecahedrons was used to simulate the melting heat transfer process in open foam metal at pore-scale under constant temperature. The results show that the porosity and conductivity of the foam metal and the conductivity of the phase change material (PCM) have a significant influence on the effective thermal conductivity of the composite PCM, while the pore size has no obvious influence. The effective thermal conductivity of composite PCMs increased with increasing foam metal thermal conductivity, and increased more rapidly with lower foam metal porosity. The effective thermal conductivity of composite PCMs is related to the ratio of foam metal conductivity to PCM conductivity. The microstructure of the foam metal had an obvious effect on the solid-liquid phase distribution during the PCM melting process, where the heat was transferred mainly through the melted liquid PCM field. Conduction was the dominant heat transfer mechanism, and natural convection in the liquid PCM was weak for the confinement of foam metals. For heat transfer during the PCM melting process, conduction through the skeleton of the porous metal played the most important role. The PCM adjacent to the heating source and foam metal frame melted first, with the fusion zone gradually spreading to the pore center. The melting rate of the PCM increased with increasing boundary temperature and thermal conductivity of the foam metal, but decreased as foam metal porosity increased. During the melting process, the liquid phase fraction did not linearly grow with time; the melting rate was very large at the initial stage, but decreased gradually with time.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 25 January 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Applied Thermal Engineering, Volume 147〈/p〉 〈p〉Author(s): Adrián Mota-Babiloni, Joaquín Navarro-Esbrí, Víctor Pascual-Miralles, Ángel Barragán-Cervera, Angelo Maiorino〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Coming refrigeration and air conditioning systems must include low GWP fluids and optimized components. An internal heat exchanger (IHX) is a common modification of the basic cycle to enhance its energy performance, and its benefits have been demonstrated with R134a and the recently developed hydrofluoro-olefin R1234yf. This paper assesses the experimental influence of a high effectiveness IHX using R134a, and the low GWP mixture R513A (a mixture of R134a and R1234yf) under different evaporating and condensing conditions (29 points tested in total). Discharge temperature has been increased up to 26 K for both fluids, and the greatest compression ratio is not feasible for R134a. The cooling capacity of the system results increased up to 5.6% for R513A whereas for R134a is around 3%. Furthermore, due to the minimum diminution of power consumption, COP also increases up to 8% for R513A and 4% for R134a. Because of the observed experimental results, high effectiveness IHX is recommended for R513A, especially for high compression ratio operations as long as the discharge temperature does not reach critical values. Finally, it has been found that Klein et al.’s and Hermes’s correlations overestimate the COP benefit and the increase in power consumption should be considered.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 5 February 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Applied Thermal Engineering, Volume 148〈/p〉 〈p〉Author(s): S.H. Hosseini, M.J. Rezaei, M. Bag-Mohammadi, Alireza Zendehboudi, G. Ahmadi〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Determining the frost layer thickness on plates is very important in heat and mass transfer processes in cryogenic equipment. In this study, the intelligent approaches of multi-layer perceptron trained by Bayesian Regulation (MLP-BR) and adaptive neuro fuzzy inference system (ANFIS) are utilized for predicting the frost layer growth on a vertical plate under natural convection and horizontal and parallel plates under forced convection. Dimensionless groups of the relevant parameters are also formed and used in this analysis. In particular, plate temperature, air temperature, air velocity, relative humidity, and time are taken as the models’ inputs. The self-organizing map (SOM) is applied to examine the influences of inputs on the performance of the selected models. It is shown that the MLP-BR-SOM model provides the best results for the test data samples with AARE of 2.57%, 6.55%, and 8.34% for test data, respectively, for the cases of vertical, horizontal, and parallel plates, respectively. In addition, three new semi-empirical equations comprising of dimensionless parameters are developed for the cases of vertical, horizontal, and parallel plates, with AARE of 12.36%, 27.18%, and 22.076%, respectively. Ultimately, the results are compared with those predicted by the existing empirical equations.〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S1359431118347987-ga1.jpg" width="433" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 5 February 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Applied Thermal Engineering, Volume 148〈/p〉 〈p〉Author(s): Eun Jung Choi, Jin Young Park, Min Soo Kim〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉 〈p〉The aim of this paper is to investigate two-phase heat transfer of HFE-7100 in mini-channels and its cooling performance in order to determine its effectiveness for a fuel cell application. Firstly, characteristics of two-phase boiling heat transfer of HFE-7100 is analyzed. It is demonstrated that two-phase boiling heat transfer coefficient of HFE-7100 in mini-channels is strongly dependent on heat flux and vapor quality but less sensitive to mass flux. Critical heat flux is observed when wall superheat is over 25 K and flow visualization method is used to examine a flow pattern change.〈/p〉 〈p〉In the second part, cooling performance and wall temperature change is investigated. Under heat generation ranges from a fuel cell, wall temperature is maintained at desirable operating temperature of polymer electrolyte membrane fuel cell (60–80 °C) and temperature difference is lower than 0.5 °C. At critical heat flux condition, wall temperature rises to over 90 °C. Also, wall temperature increases from 63.5 °C to 71.6 °C when channel pressure rises from 1.0 bar to 1.5 bar. Lastly dynamic response in wall temperature with the coolant pump control is investigated. It is found that this control method is effective to maintain low temperature difference (less than 1.5 °C) and the intermittent pump operating mode can reduce pump energy consumption.〈/p〉 〈/div〉 〈/div〉

Description: 〈p〉Publication date: 5 February 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Applied Thermal Engineering, Volume 148〈/p〉 〈p〉Author(s): M. Rao, A. Fernandes, P. Pronk, P.V. Aravind〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉 〈p〉The steel industry is one of the major sources of CO〈sub〉2〈/sub〉 emissions that are released in the manufacture and process of steel as well as in related power production. Focused on reduction of CO〈sub〉2〈/sub〉 emissions in the power production, this paper presents a novel solid oxide fuel cell-gas turbine combined heat and power system fed by coke oven gas. The solid oxide fuel cell-gas turbine system design consists of an adequate gas cleaning section for contaminants removal, solid oxide fuel cell as the main power producer and an anode offgas pressure swing adsorption based CO〈sub〉2〈/sub〉 capture unit. This system is thermodynamically and techno-economically analyzed and compared with a reheat steam turbine. Furthermore, the reheat steam turbine is retrofitted with a CO〈sub〉2〈/sub〉 capture unit. It is then compared to the solid oxide fuel cell-gas turbine system to analyse the difference in system efficiencies.〈/p〉 〈p〉The solid oxide fuel cell-gas turbine system yields an electrical efficiency of 64%, which is significantly higher than electrical efficiency achieved by both, a conventional reheat steam cycle (34.1%) and the retrofitted system (27.0%). Moreover, it depicts a combined heat and power efficiency of 73%. Results also reveal that the solid oxide fuel cell-gas turbine system can achieve a reduction of 50% in CO〈sub〉2〈/sub〉 emissions for equal power production. Furthermore, techno-economic analysis lead to a payback period of 9 years, taking into account state-of-the-art taxes and variation in the cost of components over the lifetime, without taking into account the fuel cost.〈/p〉 〈/div〉 〈/div〉

Description: 〈p〉Publication date: 1 March 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Water Research, Volume 150〈/p〉 〈p〉Author(s): Zeng Qian, Hao Tianwei, Hamish Robert Mackey, Mark C.M. van Loosdrecht, Chen Guanghao〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Sulfate-reducing bacteria (SRB) are a group of diverse anaerobic microorganisms omnipresent in natural habitats and engineered environments that use sulfur compounds as the electron acceptor for energy metabolism. Dissimilatory sulfate reduction (DSR)-based techniques mediated by SRB have been utilized in many sulfate-containing wastewater treatment systems worldwide, particularly for acid mine drainage, groundwater, sewage and industrial wastewater remediation. However, DSR processes are often operated suboptimally and disturbances are common in practical application. To improve the efficiency and robustness of SRB-based processes, it is necessary to study SRB metabolism and operational conditions. In this review, the mechanisms of DSR processes are reviewed and discussed focusing on intracellular and extracellular electron transfer with different electron donors (hydrogen, organics, methane and electrodes). Based on the understanding of the metabolism of SRB, responses of SRB to environmental stress (pH-, temperature-, and salinity-related stress) are summarized at the species and community levels. Application in these stressed conditions is discussed and future research is proposed. The feasibility of recovering energy and resources such as biohydrogen, hydrocarbons, polyhydroxyalkanoates, magnetite and metal sulfides through the use of SRB were investigated but some long-standing questions remain unanswered. Linking the existing scientific understanding and observations to practical application is the challenge as always for promotion of SRB-based techniques.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 1 February 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Water Research, Volume 149〈/p〉 〈p〉Author(s): Shiqiang Zou, Mohan Qin, Zhen He〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Forward osmosis (FO) has emerged as a potentially energy-efficient membrane treatment technology to yield high-quality reusable water from various wastewater/saline water sources. A key challenge remained to be solved for FO is reverse solute flux (RSF), which can cause issues like reduced concentration gradient and loss of draw solutes. Yet no universal parameters have been developed to compare RSF control performance among various studies, making it difficult to position us in this “battle” against RSF. In this paper, we have conducted a concise review of existing RSF reduction approaches, including operational strategies (e.g., pressure-, electrolysis-, and ultrasound-assisted osmosis) and advanced membrane development (e.g., new membrane fabrication and existing membrane modification). We have also analyzed the literature data to reveal the current status of RSF reduction. A new parameter, mitigation ratio (〈em〉MR〈/em〉), was proposed and used together with specific RSF (〈em〉SRSF〈/em〉) to evaluate RSF reduction performance. Potential research directions have been discussed to help with future RSF control. This review intends to shed more light on how to effectively tackle solute leakage towards a more cost-effective and environmental-friendly FO treatment process.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0043135418309369-fx1.jpg" width="258" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 1 February 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Water Research, Volume 149〈/p〉 〈p〉Author(s): Ni Yan, Hua Zhong, Mark L. Brusseau〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The ability of soils and sediments to promote in-situ activation of persulfate and persulfate combined with hydrogen peroxide was investigated for treatment of 1,4-dioxane (dioxane). Experiments were conducted with both batch-reactor and column systems to examine reaction rates and activation mechanisms. Four soils and aquifer sediments were used. ICP-MS and XRD analyses were used to characterize geochemical properties of the solutions and sediments, while EPR spectroscopy was used to characterize radical formation. For the batch experiments, degradation of dioxane was significantly greater in the presence of each of the four subsurface geomedia compared to the controls with no geomedia. This indicates that all four geomedia induced oxidant activation, thereby enhancing dioxane degradation. Dioxane degradation was significantly enhanced by the addition of peroxide to the persulfate solution. It is hypothesized that iron associated with the geomedia is primarily responsible for activation, and that the degree of degradation enhancement relates in part to dissolved-phase iron content. EPR results indicate that manganese oxides and soil organic matter may also have contributed to some degree to persulfate activation, and that manganese oxides enhanced activation of peroxide under the study conditions. Approximately 10% of dioxane was degraded in the miscible-displacement experiments, consistent with the short residence time compared to dioxane's half-life. The pseudo first-order rate coefficients obtained from the batch and column experiments were similar. The results of this study indicate that subsurface geomedia can induce activation of persulfate and peroxide to enhance in-situ chemical oxidation applications.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0043135418309497-fx1.jpg" width="306" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 1 February 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Water Research, Volume 149〈/p〉 〈p〉Author(s): Qinhong Cai, Zhiwen Zhu, Bing Chen, Baiyu Zhang〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Oily wastewater is a large waste stream produced by a number of industries. This wastewater often forms stable oil-in-water (O/W) emulsion. These emulsions require demulsification in order to effectively treat the water prior to release. Although biological demulsification of O/W emulsion has advantages over traditional approaches, its development is at a preliminary stage with few demulsifying bacteria reported and a need for effective screening methods for such bacteria. In this study, thirty-seven marine O/W emulsion demulsifying bacterial strains belonging to 5 genera and 15 species were reported. Cell hydrophobicity and interfacial activity played key roles in the emulsion breaking. One of the highly effective demulsifying bacteria, 〈em〉Halomonas venusta〈/em〉 strain N3-2A was identified and characterized. Both its extracellular biosurfactant and cell surface contributed to demulsification resulting in breaking of 92.5% of the emulsion within 24 h. A high throughput and effective screening strategy targeting O/W emulsion breaking bacteria using oil spreading test coupled with cell hydrophobicity test was proposed. In addition, the 37 demulsifying bacteria showed a certain degree of species/genus specific patterns of surface activity and cell hydrophobicity. The reported bacteria and the screening strategy have promising potential for the biological demulsification of O/W emulsions and oily wastewater treatment.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 1 February 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Water Research, Volume 149〈/p〉 〈p〉Author(s): Xiaofang Chen, Hongliang Yin, Guiying Li, Wanjun Wang, Po Keung Wong, Huijun Zhao, Taicheng An〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Due to the significant public health risks, there is substantial scientific interest in the increasing abundance of antibiotic-resistance bacteria (ARB) and the spread of antibiotic-resistance genes (ARGs) in aquatic environments. To clearly understand the mechanism of ARG transfer, this study examined the conjugative transfer of genes encoding resistance to cephalosporin (〈math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si1.gif" overflow="scroll"〉〈mrow〉〈mi〉b〈/mi〉〈mi〉l〈/mi〉〈msub〉〈mrow〉〈mi〉a〈/mi〉〈/mrow〉〈mrow〉〈mi〉C〈/mi〉〈mi〉T〈/mi〉〈mi〉X〈/mi〉〈/mrow〉〈/msub〉〈/mrow〉〈/math〉) and polymyxin (〈em〉mcr-1〈/em〉) from two antibiotic-resistant donor strains, namely 〈em〉E. coli〈/em〉 DH5α (CTX) and 〈em〉E. coli〈/em〉 DH5α (MCR), and to a streptomycin-resistant receptor strain (〈em〉E. coli〈/em〉 C600 (Sm)). Conjugative transfer was specifically studied under different light irradiation conditions including visible light (VL), simulated sunlight (SS) and ultraviolet light (UV〈sub〉254nm〈/sub〉). Results show that the conjugative transfer frequency was not affected by VL irradiation, while it was slightly improved (2–10 fold) by SS irradiation and extremely accelerated (up to 100 fold) by UV irradiation. Furthermore, this study also explored the link between ARG transfer and stress conditions. This was done by studying physiological and biochemical changes; oxidative stress response; and functional gene expression of co-cultured AR-〈em〉E. coli〈/em〉 strains under stress conditions. When correlated with the transfer frequency results, we found that VL irradiation did not affect the physiological and biochemical characteristics of the bacteria, or induce oxidative stress and gene expression. For SS irradiation, oxidative stress occurred slowly, with a slight increase in the expression of target genes in the bacterial cells. In contrast, UV irradiation, rapidly inactivated the bacteria, the degree of oxidative stress was very severe and the expression of the target genes was markedly up-regulated. Our study could provide new insight into the underlying mechanisms and links between accelerated conjugative transfer and oxidative stress, as well as the altered expression of genes relevant to conjugation and other stress responses in bacterial cells.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0043135418309400-fx1.jpg" width="274" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 1 February 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Water Research, Volume 149〈/p〉 〈p〉Author(s): Haojie Su, Yao Wu, Wulai Xia, Lei Yang, Jianfeng Chen, Wenxuan Han, Jingyun Fang, Ping Xie〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Catastrophic regime shifts in shallow lakes are hard to predict due to a lack of clear understanding of the associate mechanisms. Theory of alternative stable states suggests that eutrophication has profound negative effects on the structure, function and stability of freshwater ecosystems. However, it is still unclear how eutrophication destabilizes ecosystems stoichiometrically before a tipping point is reached. The stoichiometric homeostasis (〈em〉H〈/em〉), which links fine-scale process to broad-scale patterns, is a key parameter in ecological stoichiometry. Based on investigation of 97 shallow lakes on the Yangtze Plain, China, we measured nitrogen (N) and phosphorus (P) concentrations of the aboveground tissues of common submerged macrophyte species and their corresponding sediments. We found submerged macrophytes showed significant stoichiometric homeostasis for P (〈em〉H〈/em〉〈sub〉P〈/sub〉) but not for N (〈em〉H〈/em〉〈sub〉N〈/sub〉). Furthermore, 〈em〉H〈/em〉〈sub〉P〈/sub〉 was positively correlated with dominance and stability at the species level, and community production and stability at the community level. Identifying where macrophyte community collapse is a fundamental way to quantify their resilience. Threshold detection showed that macrophyte community dominated by high-〈em〉H〈/em〉〈sub〉P〈/sub〉 species had a higher value of tipping point (0.08 vs. 0.06 mg P L〈sup〉−1〈/sup〉 in lake water), indicating their strong resilience to eutrophication. In addition, macrophytes with high 〈em〉H〈/em〉〈sub〉P〈/sub〉 were predominant in relative oligotrophic sediments and have higher ability in stabilizing the water environment compared to those low-〈em〉H〈/em〉〈sub〉P〈/sub〉 ones. Our results suggested that ecosystem dominated by homeostatic macrophyte communities was more productive, stable and resilient to eutrophication. Eutrophication-induced stoichiometric imbalance may destabilize the ecosystem by altering the community structure from high-to low-〈em〉H〈/em〉〈sub〉P〈/sub〉 species. Efforts should be focused on maintaining and restoration of high homeostatic communities to make ecosystem more resilient, which can significantly improve our understanding of the critical transition mechanisms.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S004313541830945X-fx1.jpg" width="500" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 1 February 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Water Research, Volume 149〈/p〉 〈p〉Author(s): Jiuling Li, Keshab Sharma, Yiqi Liu, Guangming Jiang, Zhiguo Yuan〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Chemical dosing is a commonly used strategy for mitigating sewer corrosion and odour problems caused by sulfide production. Prediction of sewage flow variation in real-time is critical for the optimization of chemical dosing to achieve cost-effective mitigation of hydrogen sulfide (H〈sub〉2〈/sub〉S). Autoregressive (AR) models have previously been used for real-time sewage prediction. However, the prediction showed significant delays in wet weather conditions. In this paper, autoregressive with exogenous inputs (ARX) models are employed to reduce the delays with rainfall data used as model inputs. The model is applied to predicting sewage flows at two real-life sewage pumping stations (SPSs) with different hydraulic characteristics and climatic conditions. The calibrated models were capable of predicting flow rates in both cases, much more accurately than previously developed AR models under wet weather conditions. Simulation of on-line chemical dosing control based on the predicted flows showed excellent sulfide mitigation performance at reduced cost.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0043135418309424-fx1.jpg" width="317" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 1 February 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Water Research, Volume 149〈/p〉 〈p〉Author(s): Derek C. Manheim, Russell L. Detwiler, Sunny C. Jiang〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Biological drinking water treatment technologies offer a cost-effective and sustainable approach to mitigate microcystin (MC) toxins from harmful algal blooms. To effectively engineer these systems, an improved predictive understanding of the bacteria degrading these toxins is required. This study reports an initial comparison of several unstructured kinetic models to describe MC microbial metabolism by isolated degrading populations. Experimental data was acquired from the literature describing both MC removal and cell growth kinetics when MC was utilized as the primary carbon and energy source. A novel model-data calibration approach melding global single-objective, multi-objective, and Bayesian optimization in addition to a fully Bayesian approach to model selection and hypothesis testing were applied to identify and compare parameter and predictive uncertainties associated with each model structure. The results indicated that models incorporating mechanisms of enzyme-MC saturation, affinity, and cooperative binding interactions of a theoretical single, rate limiting reaction accurately and reliably predicted MC degradation and bacterial growth kinetics. Diverse growth characteristics were observed among MC degraders, including moderate to high maximum specific growth rates, very low to substantial affinities for MC, high yield of new biomass, and varying degrees of cooperative enzyme-MC binding. Model predictions suggest that low specific growth rates and MC removal rates of degraders are expected in practice, as MC concentrations in the environment are well below saturating levels for optimal growth. Overall, this study represents an initial step towards the development of a practical and comprehensive kinetic model to describe MC biodegradation in the environment.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0043135418309357-fx1.jpg" width="350" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 1 February 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Water Research, Volume 149〈/p〉 〈p〉Author(s): Soryong Chae, Tahereh Noeiaghaei, Yoontaek Oh, In S. Kim, Jin-Soo Park〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Harmful algal blooms are occurring more frequently in fresh water throughout the world. Certain cyanobacteria can produce and release potent toxic compounds, known as cyanotoxins, such as microcystins, cylindrospermopsin, saxitoxin, and anatoxin-a, and as such they have become a human and environmental health concern. Hybrid photocatalytic composites (HPCs) comprising carbon nanotubes on the surface of TiO〈sub〉2〈/sub〉 nanotubes were designed in this study. The HPCs have a selective adsorption capacity to cyanotoxins and provide photocatalytic activity to produce reactive oxygen species for the degradation of cyanotoxins. HPCs with 5.2 mg carbon nanotubes/cm〈sup〉2〈/sup〉 showed an excellent removal efficiency of microcystins-LR (〉95%) at 55.6 L/m〈sup〉2〈/sup〉/hr/bar. The HPCs more efficiently removed the relatively larger and more hydrophobic cyanotoxins (〈em〉i.e.〈/em〉, microcystin-LR) than the relatively smaller and more hydrophilic compounds, such as cylindrospermopsin, saxitoxin, and anatoxin-a. With a further increased in the carbon nanotube content to 8.6 mg/cm〈sup〉2〈/sup〉, the adsorption capacity of the HPCs for cyanotoxins increased to 70.6% for MC-LR. However, there was significant decrease in the photocatalytic activity of the HPCs for production of reactive oxygen species, and consequently a decrease in the degradation of cyanotoxins. It is considered that this device could be used to provide complete rejection of particles and pathogens, and also to significantly reduce trace organic compounds and harmful algal toxins in emergency water supplies.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0043135418309370-fx1.jpg" width="333" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: Available online 15 November 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Water Research〈/p〉 〈p〉Author(s): Tetyana Gilevska, Elodie Passeport, Mahsa Shayan, Edward Seger, Edward J. Lutz, Kathryn A. West, Scott A. Morgan, E. Erin Mack, Barbara Sherwood Lollar〈/p〉 〈div xml:lang="en"〉 〈h5〉ABSTRACT〈/h5〉 〈div〉〈p〉A key challenge in conceptual models for contaminated sites is identification of the multiplicity of processes controlling contaminant concentrations and distribution as well as quantification of the rates at which such processes occur. Conventional protocol for calculating biodegradation rates can lead to overestimation by attributing concentration decreases to degradation alone. This study reports a novel approach of assessing 〈em〉in situ〈/em〉 biodegradation rates of monochlorobenzene (MCB) and benzene in contaminated sediments. Passive diffusion samplers allowing cm-scale vertical resolution across the sediment-water interface were coupled measurements of concentrations and stable carbon isotope signatures to identify zones of active biodegradation of both compounds. Large isotopic enrichment trends in 〈sup〉13〈/sup〉C were observed for MCB (1.9 to 5.7‰), with correlated isotopic depletion in 〈sup〉13〈/sup〉C for benzene (1.0 to 7.0‰), consistent with expected isotope signatures for substrate and daughter product produced by 〈em〉in situ〈/em〉 biodegradation. Importantly in the uppermost sediments, benzene too showed a pronounced 〈sup〉13〈/sup〉C enrichment trend of up to 2.2‰, providing definitive evidence for simultaneous degradation as well as production of benzene. The hydrogeological concept of representative elementary volume was applied to CSIA data for the first time and identified a critical zone of 10-15 cm with highest biodegradation potential in the sediments. Using both stable isotope-derived rate calculations and numerical modeling, we show that MCB degraded at a slower rate (0.1-1.4 yr〈sup〉-1〈/sup〉 and 0.2-3.2 yr〈sup〉-1〈/sup〉, respectively) than benzene (3.3-84.0 yr〈sup〉-1〈/sup〉) within the most biologically active zone of the sediment, contributing to detoxification.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0043135418309503-fx1.jpg" width="500" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 1 February 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Water Research, Volume 149〈/p〉 〈p〉Author(s): Kaixiong Yang, Lin Li, Yanjie Wang, Song Xue, Yunping Han, Junxin Liu〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Wastewater treatment plants (WWTPs) are major sources of airborne bacteria, which could pose health risks to WWTP workers and surrounding residents. In this study, air samples were collected from various treatment facilities of a typical WWTP. Community compositions of airborne bacteria were identified by high-throughput sequencing technique. SourceTracker was used to determine the percentages of airborne bacteria from wastewater, sludge, ambient air, and other environment. Health risks associated with airborne bacteria were estimated based on the average daily dose rates (ADD) of exposure by inhalation and skin contact. Concentrations of airborne bacteria varied in a wide range of 23–4878 CFU/m〈sup〉3〈/sup〉. The main emission sources of airborne bacteria were treatment facilities with aeration, mechanical agitation, and located indoors. For treatment facilities located indoors, higher percentages of airborne bacteria were associated with wastewater and sludge, while more airborne bacteria were originated from the ambient air for outdoor installations. Opportunistic pathogens such as 〈em〉Micrococcus〈/em〉, 〈em〉Bacteroides〈/em〉, 〈em〉Chryseobacterium〈/em〉, 〈em〉Pseudomonas,〈/em〉 and 〈em〉Acinetobacter〈/em〉, were detected in airborne bacteria. Inhalation was the main pathway for on-site workers exposure to airborne bacteria. Due to the presence of opportunistic pathogens, strict control measures should be employed in WWTPs to reduce the infection risks.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0043135418309485-fx1.jpg" width="246" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 1 February 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Water Research, Volume 149〈/p〉 〈p〉Author(s): Luigi Rizzo, Teresa Agovino, Samira Nahim-Granados, María Castro-Alférez, Pilar Fernández-Ibáñez, María Inmaculada Polo-López〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Photo-driven advanced oxidation process (AOP) with peracetic acid (PAA) has been poorly investigated in water and wastewater treatment so far. In the present work its possible use as tertiary treatment of urban wastewater to effectively minimize the release into the environment of contaminants of emerging concern (CECs) and antibiotic-resistant bacteria was investigated. Different initial PAA concentrations, two light sources (sunlight and UV-C) and two different water matrices (groundwater (GW) and wastewater (WW)) were studied. Low PAA doses were found to be effective in the inactivation of antibiotic resistant 〈em〉Escherichia coli〈/em〉 (AR 〈em〉E. coli〈/em〉) in GW, with the UV-C process being faster (limit of detection (LOD) achieved for a cumulative energy (Q〈sub〉UV〈/sub〉) of 0.3 kJL〈sup〉−1〈/sup〉 with 0.2 mg PAA L〈sup〉−1〈/sup〉) than solar driven one (LOD achieved at Q〈sub〉UV〈/sub〉 = 4.4 kJL〈sup〉−1〈/sup〉 with 0.2 mg PAA L〈sup〉−1〈/sup〉). Really fast inactivation rates of indigenous AR 〈em〉E. coli〈/em〉 were also observed in WW. Higher Q〈sub〉UV〈/sub〉 and PAA initial doses were necessary to effectively remove the three target CECs (carbamazepine (CBZ), diclofenac and sulfamethoxazole), with CBZ being the more refractory one. In conclusion, photo-driven AOP with PAA can be effectively used as tertiary treatment of urban wastewater but initial PAA dose should be optimized to find the best compromise between target bacteria inactivation and CECs removal as well as to prevent scavenging effect of PAA on hydroxyl radicals because of high PAA concentration.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0043135418309527-fx1.jpg" width="339" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 1 February 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Water Research, Volume 149〈/p〉 〈p〉Author(s): Zahid Ur Rehman, Muhammad Ali, Hina Iftikhar, TOrove Leiknes〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Biofouling of Reverse Osmosis (RO) membrane is a significant issue for the water treatment industry. In this study, we apply the metagenomic shot-gun sequencing technology to characterise the composition and functional potential of the microbial community in a full-scale RO plant, at different stages of seawater treatment. We find 〈em〉Proteobacteria〈/em〉, 〈em〉Bacteroidetes〈/em〉 and 〈em〉Planctomycetes〈/em〉 to be the most abundant bacterial phyla. The genetic potential of the RO membrane microbial community shows the enrichment of genes involved in biofilm formation, representing the selective pressure of the biofilm formation process. We recover 31 metagenome-assembled genomes (MAGs) from intake (raw seawater), fouled RO membranes (leading and middle RO module) and brine reject water. A total of 25 MAGs are recovered from the biofilm samples (leading and middle RO modules), with 9 of them (36%) belonging to 〈em〉Planctomycetes〈/em〉. We investigate all 25 MAGs for genes (pili, flagella, quorum sensing, quorum quenching and nitrate reduction) that play an important role in biofilm formation and sustenance of cells. We show that 〈em〉Planctomycetes〈/em〉 contain genes for the formation of flagella and pili, and the reduction of nitrate. Although genes for quorum sensing are not detected, quorum quenching genes are identified in the biofilm MAGs. Our results show that 〈em〉Planctomycetes〈/em〉, along with other microbes, play an important role in the formation and sustenance of biofilms on seawater RO membranes.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0043135418309333-fx1.jpg" width="454" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 1 February 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Water Research, Volume 149〈/p〉 〈p〉Author(s): Sophie Charvet, Lasse Riemann, Johannes Alneberg, Anders F. Andersson, Julian von Borries, Uwe Fischer, Matthias Labrenz〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉 〈p〉Microbial communities are the main drivers of biogeochemical cycling of multiple elements sustaining life in the ocean. The rapidity of their response to stressors and abrupt environmental changes implies that even fast and infrequent events can affect local transformations of organic matter and nutrients. Modern molecular techniques now allow for monitoring of microbial activities and functions in the environment through the analysis of genes and expressed genes contained in natural microbial assemblages. However, messenger RNA turnover in cells can be as short as 30 seconds and stability varies greatly between transcripts. Sampling of 〈em〉in situ〈/em〉 communities involves an inevitable delay between the collection of seawater and the extraction of its RNA, leaving the bacterial communities plenty of time to alter their gene expression. The characteristics of microbial RNA turnover make time-series very difficult because samples need to be processed immediately to limit alterations to the metatranscriptomes.〈/p〉 〈p〉To address these challenges we designed an autonomous 〈em〉in situ〈/em〉 fixation multi-sampler (AFISsys) for the reliable sampling of microbial metatranscriptomes at frequent intervals, for refined temporal resolution. To advance the development of this instrument, we examined the minimal seawater volume necessary for adequate coverage of community gene expression, and the suitability of phenol/ethanol fixation for immediate and long-term preservation of transcripts from a microbial community. We then evaluated the field eligibility of the instrument itself, with two case studies in a brackish system. AFISsys is able to collect, fix, and store water samples independently at a predefined temporal resolution. Phenol/ethanol fixation can conserve metatranscriptomes directly in the environment for up to a week, for later analysis in the laboratory. Thus, the AFISsys constitutes an invaluable tool for the integration of molecular functional analyses in environmental monitoring in brackish waters and in aquatic environments in general.〈/p〉 〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0043135418309382-fx1.jpg" width="280" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 1 February 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Water Research, Volume 149〈/p〉 〈p〉Author(s): Janis E. Baeten, Damien J. Batstone, Oliver J. Schraa, Mark C.M. van Loosdrecht, Eveline I.P. Volcke〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Wastewater treatment processes with granular sludge are compact and are becoming increasingly popular. Interest has been accompanied by the development of mathematical models. This contribution simultaneously reviews available models in the scientific literature for anaerobic, aerobic and partial nitritation-anammox granular sludge reactors because they comprise common phenomena (e.g. liquid, gas and granule transport) and thus pose similar challenges. Many of the publications were found to have no clearly defined goal. The importance of a goal is stressed because it determines the appropriate model complexity and helps other potential users to find a suitable model in the vast amount of literature. Secondly, a wide variety was found in the model features. This review explains the chosen modelling assumptions based on the different reactor types and goals wherever possible, but some assumptions appeared to be habitual within fields of research, without clear reason. We therefore suggest further research to more clearly define the range of operational conditions and goals for which certain simplifying assumptions can be made, e.g. when intragranule solute transport can be lumped in apparent kinetics and when biofilm models are needed, which explicitly calculate substrate concentration gradients inside granules. Furthermore, research is needed to better mechanistically understand detachment, removal of influent particulate matter and changes in the mixing behaviour inside anaerobic systems, before these phenomena can be adequately incorporated in models. Finally, it is suggested to perform full-scale model validation studies for aerobic and anammox reactors. A spreadsheet in the supplementary information provides an overview of the features in the 167 reviewed models.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0043135418309473-fx1.jpg" width="500" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 1 February 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Water Research, Volume 149〈/p〉 〈p〉Author(s): Yi Yang, Xiaoqiong Gu, Shu Harn Te, Shin Giek Goh, Kalaivani Mani, Yiliang He, Karina Yew-Hoong Gin〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉This study aimed to examine the drivers in shaping the occurrence and distribution of total viruses and picoplankton in tropical freshwater ecosystems. Flow cytometry was used to quantify the concentrations of total viruses, picoheterotrophs, picophytoplankton, and picocyanobacteria. Three land use patterns (urban-, agriculture- and parkland-dominated) were evaluated using ArcGIS. Significant correlations were observed between water-borne microbial targets and water quality parameters (0.175 ≤ |r| ≤ 0.441), nutrients (0.250 ≤ r ≤ 0.570) and land use factors (0.200 ≤ |r| ≤ 0.460). In particular, the concentrations of total viruses and picoheterotrophic cells were higher in catchments whereas the abundances of picophytoplankton and picocyanobacteria were higher in reservoirs. Total viruses and picoplankton had higher concentrations in urban- and agriculture-dominated areas, probably due to anthropogenic inputs and agricultural inputs, respectively. Although surface water is a complex matrix influenced by niche-based (i.e., physicochemical properties, nutrients, land use impact etc.) and neutral-based factors (i.e., ecological drift, dispersal and species), land use patterns could help to elucidate the occurrence and distribution of the total microbial community at the macroscopic level. Meanwhile, inter-correlations among viruses, picoplankton and picoheterotrophs (0.715 ≤ r ≤ 0.990) also substantiates their mutual interactions in influencing the microbial community. Furthermore, the relationships between total microbial cells and bacterial and viral indicators were also investigated. Concentrations of total viruses, picoplankton and picoheterotrophs were positively correlated with bacterial indicators (0.427 ≤ r ≤ 0.590) and viral indicators (0.201 ≤ r ≤ 0.563). These results indicated that faecal and viral contamination could contribute to the numbers of total viruses and bacteria.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0043135418309436-fx1.jpg" width="398" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 1 February 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Water Research, Volume 149〈/p〉 〈p〉Author(s): Yoann Perrin, Didier Bouchon, Vincent Delafont, Laurent Moulin, Yann Héchard〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The microbiological water quality of drinking water distribution system (DWDS) is of primary importance for human health. High-throughput sequencing has gained more and more attention in the last decade to describe this microbial diversity in water networks. However, there are few studies describing this approach on large drinking water distribution systems and for extended periods of time. To fill this gap and observe the potential subtle variation in microbiota of a water network through time and space, we aimed to apply high-throughput sequencing of the 16S rRNA gene approach to characterize bacterial communities of the Paris’ DWDS over a one-year period. In this study, the Paris network, composed of four different DWDSs, was sampled at 31 sites, each month for one year. The sampling campaign was one of the largest described so far (n = 368) and the importance of key spatio-temporal and physico-chemical parameters was investigated. Overall, 1321 taxa were identified within the Paris network, although only fifteen of them were found in high relative abundance (〉1%) in all samples. Two genera, 〈em〉Phreatobacter〈/em〉 and 〈em〉Hyphomicrobium〈/em〉 were dominant. The whole bacterial diversity was not significantly affected between the four DWDSs (spatial parameter) and by physico-chemical parameters. However, the bacterial diversity was slightly modified over the one-year period (temporal parameter) as we were able to observe DWDS microbiome perturbations, presumably linked to a preceding flood event. Comparison of high-throughput sequencing of the 16S rRNA gene amplicons vs. cultivation-based techniques showed that only 1.8% of bacterial diversity was recovered through cultivation. High throughput sequencing has made it possible to monitor DWDS more accurately than conventional methods by describing the whole diversity and detecting slight fluctuations in bacterial communities. This method would be further used to supervise drinking water networks, to follow any perturbations due to internals events (such as treatments) or external events (such as flooding).〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0043135418309345-fx1.jpg" width="500" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 1 March 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Water Research, Volume 150〈/p〉 〈p〉Author(s): Katsuki Kimura, Hiroki Uchida〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Intensive membrane cleaning can be used with ceramic membranes since they are physically/chemically robust. It might therefore be possible for membrane bioreactors (MBRs) to be operated under the condition of a high membrane flux when ceramic membranes are used with such intensive membrane cleaning. In this study, bench-scale MBRs equipped with flat-sheet ceramic membranes were operated for long periods. Circulation of granular materials (cylindrical polyurethane) in the tank and frequent chemically enhanced backwash (CEB) were used as intensive physical cleaning and chemical cleaning in this study, respectively. Experiments were carried out with synthetic wastewater. The use of granular materials, which can cause significant damage to polymeric membranes (Kurita et al., 2015), was effective for controlling the formation of cake (deposition of microbial flocs) on the surface of the ceramic membranes. When both mechanical cleaning using the granular materials and CEB with 1000 ppm of sodium hypochlorite (NaClO) were applied, contrary to an expectation, evolution of reversible fouling (formation of a transparent gel layer on the membrane surface) became uncontrollable, whereas irreversible fouling was effectively controlled. The use of NaClO induced release of organic macromolecules via biomass decay, leading to the evolution of reversible fouling. When the intensity of CEB with NaClO was adequately lowered, with the aid of the mechanical cleaning using the granules, the bench-scale MBR could be operated stably under an elevated membrane flux for a long period (〉70 days). It was postulated that the adjustment of CEB intensity preferably altered properties of organic macromolecules released from biomass: the structure of the gel layer was porous when the CEB intensity was lowered. When CEB is used in MBRs, it is thus important to balance cleaning efficiency and its harmful effect on biomass. When adequate CEB is used with intensive mechanical cleaning, MBRs with ceramic membranes can be operated under high flux conditions.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0043135418309515-fx1.jpg" width="375" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 25 February 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Applied Thermal Engineering, Volume 149〈/p〉 〈p〉Author(s): Babak Golkar, Sadegh Nikbakht Naserabad, Fatemeh Soleimany, Mansour Dodange, Amir Ghasemi, Hamid Mokhtari, Pooria Oroojie〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The consequences of water crisis in terms of political, social and environmental impacts have been motivated in this paper to recognize the hybrid wet/dry cooling systems of power plant in Iran. The existence of temperature constraints for consumers connected to the hybrid cooling tower, Space constraints for the construction of auxiliary system, devoting attention to high Net Present Value (NPV) of the project over the course of 25 years, Returning the appropriate capital, Optimal Design of air cooler and it's desirable performance over the course of a year were the reasons led to use of the genetic algorithm (GA) in this paper. The GA should optimize the design of the air cooler, according to that, at one functional point of a year, the lowest investment costs and the lowest cost of utilization in one year will happen. The cost of utilization in this project including: water consumption (makeup water of the cycle), fan power consumption (wet and dry block of hybrid cooling system), as well as chemical additives to water. The results illustrated that the proposed algorithm usage, applying a proper control system, taking into account the standards in the written code and determining the optimization intervals according to the manufacturer's data could conclude to the design of an air cooler, which can be constructed by inquiring from the manufacturing companies. The results also indicated that optimized design of hybrid cooling tower could reduce water consumption about 63% over the course of one year, return on investment by 5 years, develop NPV up to 40 M€ and enhance steam turbine power.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 25 February 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Applied Thermal Engineering, Volume 149〈/p〉 〈p〉Author(s): Cui Li, Yanzhong Li, Yiwei Cheng, Erfeng Chen, Zhan Liu, Jiaojiao Wang〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉This paper presents a numerical study on the transient cooldown process of liquid rocket engine by a passive recirculation precooling system. An unsteady mathematical model is developed by considering the interaction of heat dissipation from solid structure with the time- and location- dependent two-phase flow, and the predicted values show good agreements with experiments. The results demonstrate the roles of boiling regimes, and reveal distinct thermal and flow characteristics from single pipe cooldown and bleed precooling. The liquid rewetting front propagates along the flow direction in the vertical feed line and the turbopump related horizontal pipes, with the exception that opposite propagation appears in the upward recirculation line and causes inverted axial temperature distributions and faster cooling of exit. In terms of the time for meeting the turbopump operation requirement, large-diameter recirculation line and high liquid level in the ullage discharging condition are advantageous to the precooling of cryogenic pump, while subcooled liquid and high liquid level in liquid discharging condition prolong the cooldown process and are undesirable. The dependence of cooldown time on subcooling degree, relative liquid level and recirculation line diameter can be described by linear, cubic and exponential functions, respectively.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 March 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Water Research, Volume 151〈/p〉 〈p〉Author(s): Emily Garner, Mandu Inyang, Elisa Garvey, Jeffrey Parks, Caitlin Glover, Assumption Grimaldi, Eric Dickenson, Justin Sutherland, Andrew Salveson, Marc A. Edwards, Amy Pruden〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Little is known about how introducing recycled water intended for direct potable reuse (DPR) into distribution systems and premise plumbing will affect water quality at the point of use, particularly with respect to effects on microbial communities and regrowth. The examination of potential growth of opportunistic pathogens (OPs) and spread of antibiotic resistance genes (ARGs), each representing serious and growing public health concerns, by introducing DPR water has not previously been evaluated. In this study, the impact of blending purified DPR water with traditional drinking water sources was investigated with respect to treatment techniques, blending location, and blending ratio. Water from four U.S. utility partners was treated in bench- and pilot-scale treatment trains to simulate DPR with blending. Water was incubated in simulated premise plumbing rigs made of PVC pipe containing brass coupons to measure regrowth of total bacteria (16S rRNA genes, heterotrophic plate count), OPs (〈em〉Legionella〈/em〉 spp., 〈em〉Mycobacterium〈/em〉 spp., 〈em〉Pseudomonas aeruginosa〈/em〉), ARGs (〈em〉qnr〈/em〉A, 〈em〉van〈/em〉A), and an indicator of horizontal gene transfer and multi-drug resistance (〈em〉int〈/em〉I1). The microbial community composition was profiled and the resistome (i.e., all ARGs present) was characterized in select samples using next generation sequencing. While regrowth of total bacteria (16S rRNA genes) from the start of the incubation through week eight consistently occurred across tested scenarios (Wilcoxon, p ≤ 0.0001), total bacteria were not more abundant in the water or biofilm of any DPR scenario than in the corresponding conventional potable condition (p ≥ 0.0748). Regrowth of OP marker genes, 〈em〉qnr〈/em〉A, 〈em〉van〈/em〉A, and 〈em〉int〈/em〉I1 were not significantly greater in water or biofilm for any DPR blends treated with advanced oxidation compared to corresponding potable water (p ≥ 0.1047). This study of initial bacteria colonizing pipes after introduction of blended DPR water revealed little evidence (i.e., one target in one water type) of exacerbated regrowth of total bacteria, OPs, or ARGs in premise plumbing.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0043135418310133-fx1.jpg" width="500" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 25 February 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Applied Thermal Engineering, Volume 149〈/p〉 〈p〉Author(s): S. Anitha Kumari, S. Srinivasan〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The paper investigates a comprehensive approach for ash fouling monitoring and an optimized soot-blow mechanism for a thermal power plant reheater. A dynamic nonlinear regression model is designed to monitor the Cleanliness Factor (CF) of reheater and thereby an optimized soot-blow strategy is proposed to determine the critical CF and the duration of soot-blow cycle. The result in this case-study shows that steam consumed per soot-blow cycle is reduced and also the amount of fuel used per day is saved by adopting the proposed soot-blow strategy. The proposed method can be implemented as guidance for soot-blow operation in thermal power plants without any need for additional hardware and with a minimal computation.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 March 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Water Research, Volume 151〈/p〉 〈p〉Author(s): Laura M.S. Seelen, Giovanna Flaim, Joost Keuskamp, Sven Teurlincx, Raquel Arias Font, Duygu Tolunay, Markéta Fránková, Kateřina Šumberová, Maria Temponeras, Mirjana Lenhardt, Eleanor Jennings, Lisette N. de Senerpont Domis〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉 〈p〉Litter decomposition is a vital part of the global carbon cycle as it determines not only the amount of carbon to be sequestered, but also how fast carbon re-enters the cycle. Freshwater systems play an active role in the carbon cycle as it receives, and decomposes, terrestrial litter material alongside decomposing aquatic plant litter. Decomposition of organic matter in the aquatic environment is directly controlled by water temperature and nutrient availability, which are continuously affected by global change.〈/p〉 〈p〉We adapted the Tea Bag Index (TBI), a highly standardized methodology for determining soil decomposition, for lakes by incorporating a leaching factor. By placing Lipton pyramid tea bags in the aquatic environment for 3 h, we quantified the period of intense leaching which usually takes place prior to litter (tea) decomposition. Standard TBI methodology was followed after this step to determine how fast decomposition takes place (decomposition rate, 〈em〉k〈/em〉〈sub〉〈em〉1〈/em〉〈/sub〉) and how much of the material cannot be broken down and is thus sequestered (stabilization factor, 〈em〉S〈/em〉). A Citizen Science project was organized to test the aquatic TBI in 40 European lakes located in four climate zones, ranging from oligotrophic to hypereutrophic systems. We expected that warmer and/or eutrophic lakes would have a higher decomposition rate and a more efficient microbial community resulting in less tea material to be sequestered.〈/p〉 〈p〉The overall high decomposition rates (〈em〉k〈/em〉〈sub〉〈em〉1〈/em〉〈/sub〉) found confirm the active role lakes play in the global carbon cycle. Across climate regions the lakes in the warmer temperate zone displayed a higher decomposition rate (〈em〉k〈/em〉〈sub〉〈em〉1〈/em〉〈/sub〉) compared to the colder lakes in the continental and polar zones. Across trophic states, decomposition rates were higher in eutrophic lakes compared to oligotrophic lakes. Additionally, the eutrophic lakes showed a higher stabilization (〈em〉S〈/em〉), thus a less efficient microbial community, compared to the oligotrophic lakes, although the variation within this group was high. Our results clearly show that the TBI can be used to adequately assess the decomposition process in aquatic systems. Using “alien standard litter” such as tea provides a powerful way to compare decomposition across climates, trophic states and ecosystems.〈/p〉 〈p〉By providing standardized protocols, a website, as well as face to face meetings, we also showed that collecting scientifically relevant data can go hand in hand with increasing scientific and environmental literacy in participants. Gathering process-based information about lake ecosystems gives managers the best tools to anticipate and react to future global change. Furthermore, combining this process-based information with citizen science, thus outreach, is in complete agreement with the Water Framework Directive goals as set in 2010.〈/p〉 〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0043135418310121-fx1.jpg" width="334" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 1 March 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Water Research, Volume 150〈/p〉 〈p〉Author(s): Jing Ai, Weijun Zhang, Guiying Liao, Feifei Chen, Dongsheng Wang〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Waste activated sludge (WAS) contains many anionic functional groups which can interact with heavy metal ions through electrostatic action and complexation reactions. The transition metals adsorbed in WAS can catalyze sludge pyrolysis in anaerobic conditions and improve structural properties of organic matter. In this work, a multistage WAS utilization process for preparing the carbon-based Fenton-like catalysis materials is proposed. More specifically, WAS is firstly used as an adsorbent for heavy metals (Cu and Ni) removal, and then complexes are converted into heterogeneous Fenton-like carbon-based catalysts through oxygen-free pyrolysis. The mechanisms of interactions between extracellular polymeric substances (EPS) and metals are investigated, and the physicochemical properties of sludge-based carbons (SBC) are comprehensively characterized using varies techniques. It is found that WAS is an excellent adsorbent for Cu and Ni removal, which is mainly due to the coordination and electrostatic interactions between EPS and heavy metals. Cu and Ni adsorbed in WAS significantly improved the porous structure of SBC. Both adsorption and catalytic oxidization of Cu/Ni-SBC contribute the removal of E2 in real wastewater. The E2 removal mechanism is explored by electron-spin resonance spectroscopy (ESR) analysis, and it is found that both of 〈sup〉.〈/sup〉O〈sub〉2〈/sub〉〈sup〉−〈/sup〉 and 〈sup〉.〈/sup〉OH radicals are responsible for E2 degradation in Cu(II)-SBC-H〈sub〉2〈/sub〉O〈sub〉2〈/sub〉, while 〈sup〉.〈/sup〉O〈sub〉2〈/sub〉〈sup〉−〈/sup〉 radicals contributes to E2 degradation in Ni(II)-SBC-H〈sub〉2〈/sub〉O〈sub〉2〈/sub〉 system, so the former performed better than the latter in total removal of E2. Besides, Cu(II) and Cu(I) are both formed in Cu(II)-SBC during the oxidation process, while only Ni(II) is found in the Ni(II)-SBC-H〈sub〉2〈/sub〉O〈sub〉2〈/sub〉 process, confirming that different catalytic oxidation reactions are occurred in the Cu(II)-SBC-H〈sub〉2〈/sub〉O〈sub〉2〈/sub〉 and Ni(II)-SBC-H〈sub〉2〈/sub〉O〈sub〉2〈/sub〉 processes. This study facilitates a great strategy to the sludge multi-stage circulating utilization and a better understanding about the role of the Cu/Ni existed in SBC during the estrogens removal process.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0043135418310182-fx1.jpg" width="329" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 25 February 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Applied Thermal Engineering, Volume 149〈/p〉 〈p〉Author(s): Yanquan Liu, Leming Cheng, Jieqiang Ji, Weiguo Zhang〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉High contents of alkali and alkali earth metals (AAEMs) induce severe ash slagging and fouling during coal combustion. In this regard, co-combustion is an effective method to mitigate ash deposition. The ash deposition behavior in co-combusting high-alkali Zhundong (ZD) coal and a bituminous coal, i.e. Shenhua (SH) coal was tested in a 30 kW circulating fluidized bed test system. The results revealed that the condensation of Na〈sub〉2〈/sub〉SO〈sub〉4〈/sub〉 triggered the slag formation of ZD coal in the furnace. The Na-Ca-Fe eutectics were responsible for the melting or partial melting of slags at high temperatures. After blending SH coal with ZD coal, the volatilization of Na was effectively suppressed, and compacted slags practically disappeared at 20% blending ratio of SH coal. In the convective backpass, fine particles (〈10 µm) tended to be deposited on the leeward side of the heating surface because of the eddy impaction. As the blending ratio of SH coal increased, the size distribution of fly ash shifted to a large size range, because of the dilution effect and capture of AAEMs by silicates or aluminosilicates. The minimum blending ratio of SH coal was recommended as 20% to mitigate the ash deposition tendency of ZD coal.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 25 February 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Applied Thermal Engineering, Volume 149〈/p〉 〈p〉Author(s): Shou-Guang Yao, Chen Chen, Min Xiao, Miao-Miao Jin〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The traditional method of sneak analysis of a thermal system is based on mass flow and cannot reflect system functionality and overall characteristics. Therefore, this study presents a network tree topology model based on energy flow. The heat transfer process in the thermal system is described by introducing the concept of energy flow. According to the design function of the thermal system, hot and cold source of the system are defined as the beginning and end of path search, respectively. All possible paths of heat transfer for the thermal system are obtained. The method is applied in the central cooling system of a ship and compared with sneak analysis based on mass flow. Results of the comparison show that sneak analysis based on energy flow can find new sneak problems on the basis of sneak analysis based on mass flow. Thus, the new method is feasible and effective.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 25 February 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Applied Thermal Engineering, Volume 149〈/p〉 〈p〉Author(s): O. Ribé, R. Ruiz, M. Quera, J. Cadafalch〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Energy recovery elements play a major role in the efficiency and sustainability of building ventilation systems. The use of a sensible or total energy recovery ventilator is a key decision for ventilation systems designers. However, there is a lack of technical tools and developments to support this decision. The authors present a procedure to develop a simple decision tool for designers based on hourly values of the outdoor weather conditions and that can be applied to any kind of building. Results of the procedure are presented in simple-to-use isoline maps and tables. In order to assess credibility of the model used in the procedure, data published in the literature have been used as a reference, showing good accordance. As an example, the procedure has been applied to the Spanish area considering 48 different locations. Results have been presented and discussed. Their analysis shows as the market-accepted recommendation of using energy recovery ventilators in locations with high relative humidity during the summer should be reconsidered.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 5 February 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Applied Thermal Engineering, Volume 148〈/p〉 〈p〉Author(s): Beomjin Kwon, Nicholas I. Maniscalco, Anthony M. Jacobi, William P. King〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉This paper reports two-phase cooling in compact cross-flow microchannel heat exchangers with high power density up to 180 W/cm〈sup〉3〈/sup〉. The performance is enabled by high-speed air flow through microchannels and two-phase condensation of refrigerant R245fa. The heat exchangers were realized in 1 cm〈sup〉3〈/sup〉 blocks of copper alloy, using micro-electrical-discharging machining. Two heat exchanger designs were analyzed, fabricated, and tested. The first device has 150 air-side channels of diameter 520 μm, and the second device has 300 air-side channels of diameter 355 μm. In both cases the refrigerant channels are 2.0 × 0.5 mm〈sup〉2〈/sup〉. The heat exchangers were operated with Reynolds number between 7500 and 20,500 for the air flow and with mass flux between 330 and 750 kg/m〈sup〉2〈/sup〉 s for the refrigerant flow. The refrigerant temperature at the channel entrance was 80 °C, which is near the maximum operating temperature for some electronic devices. For comparison purposes, the devices were also tested with single-phase refrigerant flows. This work demonstrates the potential of high power density heat exchangers that leverage advanced manufacturing technologies to fabricate miniature channels.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 5 February 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Applied Thermal Engineering, Volume 148〈/p〉 〈p〉Author(s): Kritsada On-ai, Niti Kammuang-lue, Pradit Terdtoon, Phrut Sakulchangsatjatai〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The effects of centrifugal acceleration and heat inputs on physical phenomena inside a rotating closed-loop pulsating heat pipe (RCLPHP) are considered by implying from the temperature variation of the working fluid, that are amplitude and frequency of temperature variations. The higher amplitude and frequency of the temperature imply to the longer vapor plugs and the higher flow velocity, respectively. From the experiments, when centrifugal acceleration increases, the temperature amplitude decreases. The flow pattern changes from the annular flow to the slug flow. The temperature frequency increases, the working fluid flows with a higher velocity. The flow direction changes from an oscillatory flow to a circulatory flow. Therefore, the thermal resistance decreases. Moreover, when the heat input increases, the temperature amplitude and frequency increase. The flow pattern changes from the slug flow to the annular flow with an intermittent liquid slug with higher flow velocity, thus, the thermal resistance decreases.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 5 February 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Applied Thermal Engineering, Volume 148〈/p〉 〈p〉Author(s): Freek Van Riet, Eddy Janssen, Gunther Steenackers, Ivan Verhaert〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉 〈p〉Cogeneration (CHP) has great potential to save primary energy in collective residential buildings. However, these savings and their associated financial benefits are influenced by the design of the complete heat production system, which typically includes, besides the CHP itself, an auxiliary boiler and a storage tank. Both scientific literature and design guides focus little on the hydronic aspects of that design, although the performance of a heat production system is extremely prone to it.〈/p〉 〈p〉Therefore, this paper evaluates different hydronic designs of a central heat production system with CHP. First, an overview is given of the state-of-the-art hydronic design concepts that are used in the private sector. Two new concepts are proposed as improvements to the existing ones: one to integrate the CHP and one to integrate the boiler. A morphological chart is developed to classify the features of both the conventional and novel designs. Second, the performance of all the design concepts (and their 54 combinations) are evaluated based on a case study of an apartment block with 24 apartments. This evaluation is made by means of dynamic building system simulations.〈/p〉 〈p〉The results show that maximal primary energy can be saved if the CHP is integrated according to the novel CHP design, which allows a variable flow rate through the CHP. This concept should be preferred in a design process. Multiple hydronic configurations of the boiler, of which one is the novel hydronic boiler concept, resulted in a similar performance. Therefore, designers are advised to make a case-specific comparison to decide which one to take. The morphological chart and methodology elaborated in this paper provide a basis to make that decision.〈/p〉 〈/div〉 〈/div〉

Description: 〈p〉Publication date: 5 February 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Applied Thermal Engineering, Volume 148〈/p〉 〈p〉Author(s): Bingxuan Lin, Yun Wu, Zhibo Zhang, Dongliang Bian, Di Jin〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Ignition enhancement in a lean-burn combustor under low pressure is the biggest challenge for high altitude long endurance aircraft. In this study, plasma-assisted ignition using multi-channel spark discharge is proposed according to the theory of critical flame radius (R〈sub〉c〈/sub〉). A time-phased breakdown method is adopted to separate the breakdown stage from the discharge. The arc stage is restrained to reduce energy loss and maintain high voltage. Ignition experiments using single-channel spark discharge (SSD), concentrated multi-channel spark discharge (MSD) and distributed MSD were conducted. The results showed that R〈sub〉c〈/sub〉 is crucial for the ignition. The ignition probability of SSD drops quickly as pressure decreases due to the requirement of a larger R〈sub〉c〈/sub〉. The enhancement of concentrated MSD ignition is obvious at the same initial pressure than that of SSD and distributed MSD. The ignition enhancement is obtained only when the multi-channel combines to create a much larger ignition kernel and exceeds R〈sub〉c〈/sub〉 easily. Still, the ignition capability of MSD at extremely low pressure with lean and stoichiometric mixture does not perform as expected due to the splitting of the flame kernel. MSD can enhance ignition to flame transition but has little influence on the subsequent flame propagation.〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S1359431118353225-ga1.jpg" width="280" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 1 March 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Water Research, Volume 150〈/p〉 〈p〉Author(s): Dong An, Yanan Chen, Bin Gu, Paul Westerhoff, David Hanigan, Pierre Herckes, Natalia Fischer, Samantha Donovan, Jean Philippe Croue, Ariel Atkinson〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉N-nitrosodimethylamine (NDMA) is a chloramine disinfection by-product, and its formation in drinking waters can increase due to the addition of cationic polydiallyldimethylammonium chloride (polyDADMAC). PolyDADMAC is a cationic polymer added as a coagulant or coagulant aid to enhance turbidity removal during sedimentation and filtration. This paper answers two central questions to understanding the nature of the NDMA precursors in polyDADMAC. First, what is the reactivity of different molecular weight (MW) fractions of polyDADMAC with chloramines? NDMA formation potential (NDMAFP) and kinetic experiments with chloramines were conducted for non-fractionated (raw) and size-excluded fractions (〈3K, 3–10K, and 〉10K Da.) of polyDADMAC. The lower MW fraction (〈3K Da.) of polyDADMAC solutions was responsible for forming 64 ± 6% of the NDMA, despite containing only 8.7 and 9.8% of the carbon or nitrogen present in the bulk polymer. The chloramine demand kinetics of the lowest MW fraction were also 〉2× faster than the higher MW fractions. Therefore, in a water treatment application the lower MW polyDADMAC likely contributes to most of the NDMA attributed to the use of polyDADMAC. The second question was: can 〈sup〉1〈/sup〉H and 〈sup〉13〈/sup〉C nuclear magnetic resonance spectroscopy (NMR) be used to characterize the molecular structures in polyDADMAC that react with chloramines? A peak for 〈sup〉1〈/sup〉H NMR dimethylamine (DMA), a known low MW NDMA precursor, was found in a commercial polyDADMAC solution and decreased upon chloramination. The estimated DMA alone could not account for the observed NDMAFP, indicating the presence of other low MW precursors. Diffusion order spectroscopy (DOSY) NMR also showed multiple lower MW organics in polyDADMAC that change upon chloramination, including a 1.5× decrease in MW, suggesting chloramines cleave C〈img src="https://sdfestaticassets-eu-west-1.sciencedirectassets.com/shared-assets/16/entities/sbnd"〉C or C〈img src="https://sdfestaticassets-eu-west-1.sciencedirectassets.com/shared-assets/16/entities/sbnd"〉N bonds. These reactions may produce intermediates responsible for NDMA formation. Polymer manufacturers could use NMR to synthesize polyDADMAC with less DMA and other low MW compounds that produce NDMA upon chloramination.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0043135418310108-fx1.jpg" width="362" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 5 February 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Applied Thermal Engineering, Volume 148〈/p〉 〈p〉Author(s): Xiuzhen Li, Dongsheng Zhu, Jinfei Sun, Xun Mo, Shijie Liu〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Twisted oval tube is also a finned tube in a sense, especially when used in crossflow, although the fins of the twisted oval tube are invisible. An experimental research on heat transfer and pressure drop performance of twisted oval tube bundle with staggered layout is conducted. The correlations of Nusselt number and pressure drop coefficient deduced from this paper are well compatible with experimental data, which could provide a theoretical reference of twisted oval tubes for industrial applications.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 5 February 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Applied Thermal Engineering, Volume 148〈/p〉 〈p〉Author(s): Sheng Wang, Hsiu-Hung Chen, Chung-Lung Chen〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉An experimental study was carried out to investigate the heat transfer, pressure drop and flow instability characteristics associated with the flow pattern of deionized water during two-phase boiling in a silicon-based manifold microchannel heat sink coated with silicon nanowires (SiNWs) compared to a plain-wall device. The manifold microchannel device featured parallel transverse microchannels etched on a silicon substrate and longitudinal microchannels etched on a glass cover plate. Silicon nanowires were generated on the bottom and the sidewalls of the silicon microchannels. A closed-loop experimental system was constructed to demonstrate thermal and hydraulic performance. Experimental results were presented with mass fluxes ranging from 250 to 1250 kg/m〈sup〉2〈/sup〉 s and subcooled inlet temperatures from 15 K to 65 K. Results for the SiNWs device showed an approximate 20% improvement in heat flux rejection compared to the plain-wall device under the same wall superheat conditions. A subcooled inlet temperature of 65 K associated with a mass flux of 1250 kg/m〈sup〉2〈/sup〉 s is shown to be capable of dissipating an effective heat flux of 431.3 W/cm〈sup〉2〈/sup〉 with a wall superheat of about 85 K. Overall, the SiNW coatings proved positive effects on enhancing the flow boiling heat transfer with slower pressure drop increase, meanwhile the three-dimensional manifold microchannel design is revealed to effectively mitigate flow instability during the entire single and two-phase flow regions. This indicates great potential in utilizing three-dimensional flows by integrating SiNWs surface structures in high heat flux cooling applications.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 5 February 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Applied Thermal Engineering, Volume 148〈/p〉 〈p〉Author(s): Zhiming Xu, Yu Zhao, Jingtao Wang, Hongliang Chang〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Inhibition of calcium carbonate (CaCO〈sub〉3〈/sub〉) fouling using sodium carboxymethyl cellulose (SCMC) was investigated in this study, focusing on the effect of the SCMC concentration on the fouling characteristics of CaCO〈sub〉3〈/sub〉 on the stainless steel surface. The fouling characteristics were investigated via pH displacement method, electrochemical impedance spectroscopy, and dynamic experiment analysis. The experimental results indicated that these three methods provided a consistent conclusion: SCMC exhibited a promising performance of fouling inhibition, and the inhibition efficiency and induction period of CaCO〈sub〉3〈/sub〉 fouling increased with increasing SCMC concentration ranging from 50 to 200 mg L〈sup〉−1〈/sup〉. The inhibition efficiency reached 93.2% for SCMC concentration of 200 mg L〈sup〉−1〈/sup〉. Scanning electron microscopy images of CaCO〈sub〉3〈/sub〉 fouling changed from irregular slender needles and clusters to small chips with the addition of SCMC. Moreover, a protective film was formed on the stainless steel surface by adsorption of the constituent of SCMC in the presence of SCMC, directly preventing the deposition of CaCO〈sub〉3〈/sub〉 fouling on stainless steel surface.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 25 February 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Applied Thermal Engineering, Volume 149〈/p〉 〈p〉Author(s): Heng Chen, Yao Xiao, Gang Xu, Jidong Xu, Xianhuai Yao, Yongping Yang〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Comprehensive and parametric analyses were conducted to investigate the thermal characteristic of the high back-pressure (HBP) heating process based on a 300 MW coal-fired combined heat and power (CHP) unit. The results indicated that the HBP design promoted the thermal efficiency of the unit by 5.97% (absolute value) and cut down the standard coal consumption rate by 23.52 g/(kW·h), attributing to the exhaust steam recovery efficiency of 57% and the unit generation power increase of 24.58 MW. On the grounds of the first and second laws of thermodynamics, the detailed energy-saving mechanism of the HBP heating concept was synthetically explored by the analyses of energy and exergy flows and graphical exergy, and the results showed that the HBP heating configuration improved the unit performance by reducing the exhaust steam energy loss and the extraction steam flow rate and raising the exergy efficiency of the heat exchange process. The impacts of the primary parameters (unit generation load, unit heating load, supply & return-water temperatures and turbine back-pressure) on the performance of the HBP-CHP unit were also examined and optimization suggestions were put forward. Besides, the heat and power coupling characteristic of the HBP-CHP unit was discussed.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 5 February 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Applied Thermal Engineering, Volume 148〈/p〉 〈p〉Author(s): Jia Fang, Zhongwei Meng, Jiansong Li, Yuheng Du, Yuan Qin, Yuan Jiang, Weilian Bai, George G. Chase〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Due to stringent emission standards, diesel particulate filter (DPF) is used to reduce and control particulate matter (PM) emissions for engine manufacturers. The periodical regeneration the DPF by oxidizing the accumulated PM is able to avoid pressure drop build-up and fuel efficiency decrease. This paper discusses the influence of regeneration temperature, regeneration flow rate and regeneration time on both regeneration and emission performance by regeneration test bench. From the temperature distribution profiles, the maximum temperatures were achieved at rear and center part of DPF in all the regeneration tests. When the regeneration temperature was higher than 525 °C, it was benefit to emit the large diameter particles. Increasing the flow rate had negative effect for the maximum temperature, maximum temperature gradient, and regeneration performance ratio. The trends for regeneration efficiency, total mass concentration and emitted particle average diameter were similar under different regeneration flow rates. Increasing regeneration time was benefit for improving regeneration efficiency, but it had negative effect for the performance ratio. The optimization active regeneration operating parameters were achieved after considering both regeneration and emission characteristics.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 5 February 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Applied Thermal Engineering, Volume 148〈/p〉 〈p〉Author(s): Cheng Chi, Bing Gao, Fan Yang, Ruijin Liao, Li Cheng, Liangxian Zhang〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Thermal state and insulation ability of converter transformer are significant to evaluate condition, while the impacts of nonlinear thermal-electric coupling impact are often ignored in the design analysis, and might result in misestimating its actual performance. In this paper, a bilateral thermal-electric coupling method is proposed to investigate the thermal and insulation performance of converter transformer on basis of an actual size. In addition, the influence of non-uniform temperature on the overall winding losses and the nonlinear thermal-electric coupling of insulation system are considered. Firstly, the thermal-electrical parameters coupling characteristics of insulation system in converter transformer are investigated based on the built experimental platform. Results indicate that temperature distribution would change the electrical performance all the time, while electrical-dependent characteristic of oil increases with electric field in U type curve. Then, the impact of non-uniform temperature is discussed based on the built bilateral thermal-electric coupling model, and it is proved that temperature would decrease obviously in considering the losses calculated by bilateral coupling. Finally, the nonlinear thermal-electric coupling performance of converter transformer is studied. It indicates that comprehensive factors of temperature dependence and electric filed dependence have great influences on the insulation properties. Significantly, the electric field of pressboard would decrease by 12.8% under hybrid voltage condition.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 5 February 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Applied Thermal Engineering, Volume 148〈/p〉 〈p〉Author(s): F. Favre, O. Antepara, C. Oliet, O. Lehmkuhl, C.D. Perez-Segarra〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Considering that the most common reason for electronic component failure is the excessive temperature level, an efficient thermal management design can prolong the operating life of the equipment, while also increasing its performance. Computational Fluid Dynamics and Heat Transfer (CFD&HT) have proved valuable in the study of these problems, since they can produce reliable fields of fluid flow, temperature and heat fluxes. Moreover, thanks to the recent advances in high-performance computers, CFD&HT numerical simulations are becoming viable tools to study real problems. The conventional approach, which consists of employing body-conformal meshes to the solids and fluids regions, often results costly and ineffective in applications with very complex geometries and large deformation. For these cases, an alternative approach, the Immersed Boundary Method (IBM), which employs a non-body conformal mesh and discretizes the entire domain using a special treatment in the vicinity of the solid-fluid interfaces, has proven more effective. In this work, an IBM was extended to simulate problems with conjugate heat transfer (CHT) boundary conditions taking into account the radiative exchange between surfaces. It was designed to work with any type of mesh (domain discretization) and to handle any body geometry. The implementation was validated and verified by several simulations of benchmark cases. Moreover, the IBM was applied in an industrial application which consists of the simulation of a Smart Antenna Module (SAM). All in all, the carried out studies resulted in a monolithic methodology for the simulation of realistic situations, where all three heat transfer mechanisms can be considered in complex geometries.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 1 March 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Water Research, Volume 150〈/p〉 〈p〉Author(s): Junfeng Wang, Xinshan Song, Qusheng Li, Heng Bai, Congyun Zhu, Baisha Weng, Denghua Yan, Junhong Bai〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The frequent occurrence of polycyclic aromatic hydrocarbons (PAHs) in aquatic environments is of great concern because of their teratogenicity, toxicity, carcinogenicity, and mutagenicity to plants, animals and human beings. In this study the bioelectricity generation, biodegradation, phytoextraction and substrate adsorption of phenanthrene and anthracene in a constructed wetland-microbial fuel cell (CW-MFC) were investigated with an anode electrode amended with or without biochar-nZVI. During a 182-day operation period, the average removal efficiency for phenanthrene and anthracene ranged from 88.5% to 96.4%. The concentration of phenanthrene in roots, stems and laminas of 〈em〉T. orientalis〈/em〉 was 14.9, 3.9 and 2.3 ng g〈sup〉−1〈/sup〉 respectively, while that of anthracene was 22.2, 3.1 and 1.3 ng g〈sup〉−1〈/sup〉, respectively. In addition, the application of nZVI was conducive to bioelectricity generation and organic compound degradation in the CW-MFC reactor. The distribution of the bacterial community indicated that the relative abundance of 〈em〉Bacillus〈/em〉, 〈em〉Paludibacter〈/em〉, 〈em〉Desulfovibrio〈/em〉 and 〈em〉Lactococcus〈/em〉 with a degradation capability for refractory organics was significantly increased. Especially the genus 〈em〉Bacillus〈/em〉 for excreting catalase became more abundant. The results of our study indicate how to promote bioelectricity generation and biodegradation of refractory organic compounds in a CW-MFC by improving the culture conditions for bacteria.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0043135418310042-fx1.jpg" width="369" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 1 March 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Water Research, Volume 150〈/p〉 〈p〉Author(s): Jian-Ping Zou, Ying Chen, Shan-Shan Liu, Qiu-Ju Xing, Wen-Hua Dong, Xu-Biao Luo, Wei-Li Dai, Xiao Xiao, Jin-Ming Luo, John Crittenden〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉A novel electrocatalytic system was developed to realize one-pot conversion of organic pollutants into liquid fuels such as methanol (CH〈sub〉3〈/sub〉OH) and ethanol (C〈sub〉2〈/sub〉H〈sub〉5〈/sub〉OH). The process combines the catalytic oxidation of organic pollutants with electrocatalytic reduction of CO〈sub〉2〈/sub〉. We first coupled the electrocatalytic process with SO〈sub〉4〈/sub〉〈sup〉•−〈/sup〉-based advanced oxidation processes (AOPs) for the degradation of 4-nitrophenol (4-NP) using a 3D-hexagonal Co〈sub〉3〈/sub〉O〈sub〉4〈/sub〉 anode. In this step, 4-NP was mineralized to CO〈sub〉2〈/sub〉, and then the CO〈sub〉2〈/sub〉 was converted to CH〈sub〉3〈/sub〉OH and C〈sub〉2〈/sub〉H〈sub〉5〈/sub〉OH by electrocatalytic reduction using a flower-like CuO cathode. The experimental results show the destruction of 4-NP (60 mL, 10 mg/L) can be as high as 99%. In addition, the yields of CH〈sub〉3〈/sub〉OH and C〈sub〉2〈/sub〉H〈sub〉5〈/sub〉OH were 98.29 μmol/L and 40.95 μmol/L, respectively, which represents a conversion of 41.8% of 4-NP into liquid fuels; the electron efficiency was 73.1%. In addition, we found that 3D-hexagonal arrays of Co〈sub〉3〈/sub〉O〈sub〉4〈/sub〉 with different morphologies can be obtained by adding different amounts of urea. We also investigated the formation mechanism of novel 3D-hexagonal Co〈sub〉3〈/sub〉O〈sub〉4〈/sub〉 arrays for the first time. A mechanism was proposed to explain the electrocatalytic steps involved in the conversion of 4-NP to CH〈sub〉3〈/sub〉OH and C〈sub〉2〈/sub〉H〈sub〉5〈/sub〉OH and the synergetic effects between AOPs and electrocatalysis.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0043135418310066-fx1.jpg" width="320" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 1 March 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Water Research, Volume 150〈/p〉 〈p〉Author(s): Marlies E.R. Christiaens, Kai M. Udert, Jan B.A. Arends, Steve Huysman, Lynn Vanhaecke, Ewan McAdam, Korneel Rabaey〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉 〈p〉Ammonia recovery from urine avoids the need for nitrogen removal through nitrification/denitrification and re-synthesis of ammonia (NH〈sub〉3〈/sub〉) 〈em〉via〈/em〉 the Haber-Bosch process. Previously, we coupled an alkalifying electrochemical cell to a stripping column, and achieved competitive nitrogen removal and energy efficiencies using only electricity as input, compared to other technologies such as conventional column stripping with air. Direct liquid-liquid extraction with a hydrophobic gas membrane could be an alternative to increase nitrogen recovery from urine into the absorbent while minimizing energy requirements, as well as ensuring microbial and micropollutant retention. Here we compared a column with a membrane stripping reactor, each coupled to an electrochemical cell, fed with source-separated urine and operated at 20 A m〈sup〉−2〈/sup〉. Both systems achieved similar nitrogen removal rates, 0.34 ± 0.21 and 0.35 ± 0.08 mol N L〈sup〉−1〈/sup〉 d〈sup〉−1〈/sup〉, and removal efficiencies, 45.1 ± 18.4 and 49.0 ± 9.3%, for the column and membrane reactor, respectively. The membrane reactor improved nitrogen recovery to 0.27 ± 0.09 mol N L〈sup〉−1〈/sup〉 d〈sup〉−1〈/sup〉 (38.7 ± 13.5%) while lowering the operational (electrochemical and pumping) energy to 6.5 kWh〈sub〉e〈/sub〉 kg N〈sup〉−1〈/sup〉 recovered, compared to the column reactor, which reached 0.15 ± 0.06 mol N L〈sup〉−1〈/sup〉 d〈sup〉−1〈/sup〉 (17.2 ± 8.1%) at 13.8 kWh〈sub〉e〈/sub〉 kg N〈sup〉−1〈/sup〉.〈/p〉 〈p〉Increased cell concentrations of an autofluorescent 〈em〉E. coli〈/em〉 MG1655 + prpsM spiked in the urine influent were observed in the absorbent of the column stripping reactor after 24 h, but not for the membrane stripping reactor. None of six selected micropollutants spiked in the urine were found in the absorbent of both technologies.〈/p〉 〈p〉Overall, the membrane stripping reactor is preferred as it improved nitrogen recovery with less energy input and generated an 〈em〉E. coli〈/em〉- and micropollutant-free product for potential safe reuse. Nitrogen removal rate and efficiency can be further optimized by increasing the NH〈sub〉3〈/sub〉 vapor pressure gradient and/or membrane surface area.〈/p〉 〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0043135418310017-fx1.jpg" width="500" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 1 March 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Water Research, Volume 150〈/p〉 〈p〉Author(s): Huarong Yu, Kibaek Lee, Xiaolei Zhang, Kwang-Ho Choo〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Efficient media designs for microbial quorum quenching (QQ) are essential to enable maximal biofouling control in membrane bioreactors (MBRs). Here we introduce a novel, double-layered, biocarrier design, which has QQ bacteria in the shell layer with biostimulating agents in the core, for effective membrane biofouling control. Confining the biostimulant within dense polymer materials permits its controlled release over an extended period. The provision of the biostimulant from the core to the outer shell, where the QQ bacteria are encapsulated, facilitates their prolonged survival and active life. The core-shell structured QQ bead with the stimulant inside, which inhibits biofilm formation, shows the best fouling mitigation in laboratory testing of MBRs, while enhancing signal molecule degradation and lowering exopolymer secretion. This new, layered QQ bead, which has dual functions of bioaugmentation and biostimulation, supports a highly efficient and sustainable anti-biofouling strategy.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0043135418310005-fx1.jpg" width="400" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: Available online 30 November 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Water Research〈/p〉 〈p〉Author(s): G. Wilkes, M.D. Sunohara, E. Topp, N. Gottschall, E. Craiovan, S.K. Frey, D.R. Lapen〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Predicting bacterial loading in watersheds in response to agricultural beneficial management practices (BMPs) requires understanding the effects at both the watershed and field scale. Controlling subsurface tile drainage (CTD) is a highly effective BMP at reducing nutrient losses from fields, and watersheds when employed 〈em〉en masse〈/em〉, but little work has been conducted on CTD effects on bacterial loads and densities in a watershed setting. This study compared fecal indicator bacteria (FIB) [〈em〉E. coli〈/em〉, 〈em〉Enterococcus〈/em〉, Fecal coliform, Total coliform, 〈em〉Clostridium perfringens〈/em〉] densities and unit area loads (UAL) from a pair of flat tile-drained watersheds (∼250–467 ha catchment areas) during the growing season over a 10−year monitoring period, using a before-after-control-intervention (BACI) design (i.e., test CTD watershed vs. reference uncontrolled tile drainage (UCTD) watershed during a pre CTD intervention period and a post intervention period where the test CTD watershed had CTD deployed on over 80% of the fields). With no drainage management, upstream tile drainage to ditches comprised ∼90% of total ditch discharge. We also examined FIB loads from a subset of tile drainage systems on fields to determine their load contribution to watershed drainage ditches. While there was no strong statistical evidence of a CTD effect on FIB UAL in the surface water systems, there was statistical evidence of increased FIB densities (pronounced when 〈em〉E. coli〈/em〉 〉200 MPN 100 mL〈sup〉−1〈/sup〉) in the test CTD watershed during the CTD intervention period. This was likely a result of reduced dilution/flushing in the test CTD watershed ditch due to CTD significantly decreasing subsurface drainage contributions of water to the ditch. Tile 〈em〉E. coli〈/em〉 load contributions to the ditches were low; for example, during the 6 yr post CTD intervention period they amounted to on average only ∼3 and ∼9% for the test CTD and reference and UCTD watersheds, respectively. This suggests in-stream, or off-field FIB reservoirs and bacteria mobilization drivers, dominated ditch 〈em〉E. coli〈/em〉 UAL in the watersheds during the growing season. Overall, this study suggested that the impact seasonal CTD deployment might have on increasing FIB densities in ditches receiving tile drainage, is rescinded to the CTD's capacity to reduce seasonal nutrient pollution and boost crop yields.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0043135418310030-fx1.jpg" width="500" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 1 March 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Water Research, Volume 150〈/p〉 〈p〉Author(s): Ying Shao, Hongxia Xiao, Carolina Di Paolo, Björn Deutschmann, Werner Brack, Henner Hollert, Thomas Benjamin Seiler〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Water pollution risks to human health and the environment are emerging as serious concerns in the European Union and worldwide. With the aim to achieve good ecological and chemical status of all European water bodies, the “European Water Framework Directive” (WFD) was enacted. With the framework, bioanalytical techniques have been recognized as an important aspect. However, there are limitations to the application of bioassays directly for water quality assessment. Such approaches often fail to identify pollutants of concern, since the defined priority and monitored pollutants often fail to explain the observed toxicity. In this study, we integrated an effect-based risk assessment with a zebrafish-based investigation strategy to evaluate water sample extracts and fractions collected from the Danube. Four tiered bioassays were implemented, namely RNA-level gene expression assay, protein-level ethoxyresorufin-〈em〉O〈/em〉-deethylase (EROD) assay, cell-level micronucleus assay and organism-level fish embryo test (FET). The results show that teratogenicity and lethality during embryonic development might be induced by molecular or cellular damages mediated by the aryl hydrocarbon receptor (AhR) -mediated activity, estrogenic activity and genotoxic activity. With the combination of high-throughput fractionation, this effect-based strategy elucidated the major responsible mixtures of each specific toxic response. In particularly, the most toxic mixture in faction F4, covering a log 〈em〉Kow〈/em〉 range from 2.83 to 3.42, was composed by 12 chemicals, which were then evaluated as a designed mixture. Our study applied tiered bioassays with zebrafish to avoid interspecies differences and highlights effect-based approaches to address toxic mixtures in water samples. This strategy can be applied for large throughput screenings to support the main toxic compounds identification in water quality assessment.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0043135418309680-fx1.jpg" width="362" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 15 March 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Water Research, Volume 151〈/p〉 〈p〉Author(s): Thomas Seviour, Nicolas Derlon, Morten Simonsen Dueholm, Hans-Curt Flemming, Elisabeth Girbal-Neuhauser, Harald Horn, Staffan Kjelleberg, Mark C.M. van Loosdrecht, Tommaso Lotti, M. Francesca Malpei, Robert Nerenberg, Thomas R. Neu, Etienne Paul, Hanqing Yu, Yuemei Lin〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Microbial biofilms can be both cause and cure to a range of emerging societal problems including antimicrobial tolerance, water sanitation, water scarcity and pollution. The identities of extracellular polymeric substances (EPS) responsible for the establishment and function of biofilms are poorly understood. The lack of information on the chemical and physical identities of EPS limits the potential to rationally engineer biofilm processes, and impedes progress within the water and wastewater sector towards a circular economy and resource recovery. Here, a multidisciplinary roadmap for addressing this EPS identity crisis is proposed. This involves improved EPS extraction and characterization methodologies, cross-referencing between model biofilms and full-scale biofilm systems, and functional description of isolated EPS with 〈em〉in situ〈/em〉 techniques (e.g. microscopy) coupled with genomics, proteomics and glycomics. The current extraction and spectrophotometric characterization methods, often based on the principle not to compromise the integrity of the microbial cells, should be critically assessed, and more comprehensive methods for recovery and characterization of EPS need to be developed.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0043135418309412-fx1.jpg" width="268" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 1 March 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Water Research, Volume 150〈/p〉 〈p〉Author(s): Longfei Wang, Yi Li, Peisheng Zhang, Shujuan Zhang, Peng Li, Peifang Wang, Chao Wang〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉River biofilms play fundamental roles in shaping the architecture of aquatic systems. Sorption to biofilms was thought to be a crucial mechanism controlling the fate and transport of trace emerging contaminants. This study focused on the role of in situ colonized river biofilms in the early fate of phthalate esters (PAEs) and bisphenols (BPs) at trace concentrations in a representative urban river. PAEs and BPs were readily sorbed to biofilms with uptakes of 38.2–162.5 μg/g for PAEs and 1787.7–4425.6 μg/g for BPs, respectively. The total mass and characteristics of the colonized biofilms varied in response to seasons and water qualities. The biofilm colonized in the downstream of a wastewater treatment plant exhibited the highest sorption capacity among the tested sites, possibly attributed to the higher organic contents of biofilms owing to the elevated availability of nutrients. Correlation analysis indicates that certain water qualities, e.g., TN and NH〈sub〉3〈/sub〉〈img src="https://sdfestaticassets-eu-west-1.sciencedirectassets.com/shared-assets/16/entities/sbnd"〉N, and biofilm properties, e.g., organic and polysaccharide fractions could be selected to predict the sorption capacities of river biofilms. Hydrophobic partitioning into organic matter appears to be the dominant sorption mechanism and biofilm polysaccharides were probably responsible for the adhesion of tested compounds. The contaminant partitioning into biofilm and sediment at mass/volume ratios typical for small rivers suggests that the biofilm could serve as an important sorbing matrix for the trace organic contaminants as compared to the sediments. Our work yields new insights into the early uptake and accumulation of trace plasticizers by natural biofilms, which is of significance in understanding the subsequent transport of trace organic contaminants in fluvial systems.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0043135418309825-fx1.jpg" width="378" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 1 March 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Water Research, Volume 150〈/p〉 〈p〉Author(s): Javier García-Alba, Javier F. Bárcena, Carlos Ugarteburu, Andrés García〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉This study aims to provide a method for developing artificial neural networks in estuaries as emulators of process-based models to analyse bathing water quality and its variability over time and space. The methodology forecasts the concentration of faecal indicator organisms, integrating the accuracy and reliability of field measurements, the spatial and temporal resolution of process-based modelling, and the decrease in computational costs by artificial neural networks whilst preserving the accuracy of results. Thus, the overall approach integrates a coupled hydrodynamic-bacteriological model previously calibrated with field data at the bathing sites into a low-order emulator by using artificial neural networks, which are trained by the process-based model outputs. The application of the method to the Eo Estuary, located on the northwestern coast of Spain, demonstrated that artificial neural networks are viable surrogates of highly nonlinear process-based models and highly variable forcings. The results showed that the process-based model and the neural networks conveniently reproduced the measurements of 〈em〉Escherichia coli〈/em〉 (〈em〉E. coli〈/em〉) concentrations, indicating a slightly better fit for the process-based model (R〈sup〉2〈/sup〉 = 0.87) than for the neural networks (R〈sup〉2〈/sup〉 = 0.83). This application also highlighted that during the model setup of both predictive tools, the computational time of the process-based approach was 0.78 times lower than that of the artificial neural networks (ANNs) approach due to the additional time spent on ANN development. Conversely, the computational costs of forecasting are considerably reduced by the neural networks compared with the process-based model, with a decrease in hours of 25, 600, 3900, and 31633 times for forecasting 1 h, 1 day, 1 month, and 1 bathing season, respectively. Therefore, the longer the forecasting period, the greater the reduction in computational time by artificial neural networks.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0043135418309928-fx1.jpg" width="500" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 1 March 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Water Research, Volume 150〈/p〉 〈p〉Author(s): Bestami Özkaya, Anna H. Kaksonen, Erkan Sahinkaya, Jaakko A. Puhakka〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Fluidized bed bioreactors (FBR) are characterized by two-phase mixture of fluid and solid, in which the bed of solid particles is fluidized by means of downward or upward recirculation stream. FBRs are widely used for multiple environmental engineering solutions, such as wastewater treatment, as well as some industrial applications. FBR offers many benefits such as compact bioreactor size due to short hydraulic retention time, long biomass retention on the carrier, high conversion rates due to fully mixed conditions and consequently high mass transfer rates, no channelling of flow, dilution of influent concentrations due to recycle flow, suitability for enrichment of microbes with low 〈em〉K〈/em〉〈sub〉〈em〉m〈/em〉〈/sub〉 values. The disadvantages of FBRs include bioreactor size limitations due to the height-to-diameter ratio, high-energy requirements due to high recycle ratios, and long start-up period for biofilm formation. This paper critically reviews some of the key studies on biomass enrichment via immobilisation of low growth yield microorganisms, high-rates via fully mixed conditions, technical developments in FBRs and ways of overcoming toxic effects via solution recycling. This technology has many potential new uses as well as hydrodynamic characteristics, which enable high-rate environmental engineering and industrial applications.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0043135418309904-fx1.jpg" width="461" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 1 March 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Water Research, Volume 150〈/p〉 〈p〉Author(s): Yuanfeng Wei, Hui Liu, Chengbin Liu, Shenglian Luo, Yutang Liu, Xingwen Yu, Jianhong Ma, Kai Yin, Haopeng Feng〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Although oxidation of As(III) to As(V) is deemed necessary to promote arsenic removal, the oxidation process usually involves toxic byproducts, well-defined conditions, energy input or sludge generation. Moreover, extra operations are required to remove the resulting As(V). A heterogeneous catalytic process of CuFe〈sub〉2〈/sub〉O〈sub〉4〈/sub〉 with peroxymonosulfate (PMS) is established for As(III) oxidation and adsorption. The PMS can be activated by CuFe〈sub〉2〈/sub〉O〈sub〉4〈/sub〉 to generate radical species for As(III) oxidation. The CuFe〈sub〉2〈/sub〉O〈sub〉4〈/sub〉/PMS has a stronger affinity for arsenic than CuFe〈sub〉2〈/sub〉O〈sub〉4〈/sub〉 alone. Oxidation and adsorption promote each other. As a result, the heterogeneous catalytic process is more efficient for As(III) removal than a preoxidation of As(III) followed by adsorption. The adsorption capacity for As on CuFe〈sub〉2〈/sub〉O〈sub〉4〈/sub〉/PMS reached up to 63.9 mg/g, which is much higher than that of As(III) (36.9 mg/g) or As(V) (45.4 mg/g) on CuFe〈sub〉2〈/sub〉O〈sub〉4〈/sub〉 alone. The process can work effectively over a wide range of pH values (3–9) and temperatures (10–40 °C). Coexisting ions such as sulfate, carbonate, silicate and humic acid have an insignificant effect on As(III) removal. The As(III) (1415 μg/L) can be completely oxidized to As(V) and rapidly removed to below 10 μg/L (less than 15 min) using CuFe〈sub〉2〈/sub〉O〈sub〉4〈/sub〉(0.2 g/L)/PMS(100 μM). Moreover, the As(III) (50 μg/L) can be completely oxidized and removed within 1 min. The proposed process is easily applicable for the remediation of As(III)-contaminated water under ambient conditions.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0043135418309989-fx1.jpg" width="473" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 1 March 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Water Research, Volume 150〈/p〉 〈p〉Author(s): Ian M. Bradley, Maria C. Sevillano-Rivera, Ameet J. Pinto, Jeremy S. Guest〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Suspended growth, mixed community phototrophic wastewater treatment systems (including high-rate algal ponds and photobioreactors) have the potential to achieve biological nitrogen and phosphorus recovery with effluent nutrient concentrations below the current limit-of-technology. In order to achieve reliable and predictive performance, it is necessary to establish a thorough understanding of how design and operational decisions influence the complex community structure governing nutrient recovery in these systems. Solids residence time (SRT), a critical operational parameter governing growth rate, was leveraged as a selective pressure to shape microbial community structure in laboratory-scale photobioreactors fed secondary effluent from a local wastewater treatment plant. In order to decouple the effects of SRT and hydraulic retention time (HRT), nutrient loading was fixed across all experimental conditions and the effect of changing SRT on microbial community structure, diversity, and stability, as well as its impact on nutrient recovery, was characterized. Reactors were operated at distinct SRTs (5, 10, and 15 days) with diurnal lighting over long-term operation (〉6 SRTs), and in-depth examination of the eukaryotic and bacterial community structure was performed using amplicon-based sequencing of the 18S and 16S rRNA genes, respectively. In order to better represent the microalgal community structure, this study leveraged improved 18S rRNA gene primers that have been shown to provide a more accurate representation of the wastewater process-relevant algal community members. Long-term operation resulted in distinct eukaryotic communities across SRTs, independent of the relative abundance of Operational Taxonomic Units (OTUs) in the inoculum. The longest SRT (15 days, SRT 15) resulted in a more stable algal community along with stable bacterial nitrification, while the shortest SRT (5 days, SRT 5) resulted in a less stable, more dynamic community. Although SRT was not strongly associated with overall bacterial diversity, the eukaryotic community of SRT 15 was significantly less diverse and less even than SRT 5, with a few dominant OTUs making up a majority of the eukaryotic community structure in the former. Overall, although longer SRTs promote stable bacterial nitrification, short SRTs promote higher eukaryotic diversity, increased functional stability, and better total N removal via biomass assimilation. These results indicate that SRT may be a key factor in not only controlling microalgal community membership, but community diversity and functional stability as well. Ultimately, the efficacy and reliability of NH〈sub〉4〈/sub〉〈sup〉+〈/sup〉 removal may be in tension with TN removal in mixed phototrophic systems given that lower SRTs may achieve better total N removal (via biomass assimilation) through increased eukaryotic diversity, biomass productivity, and functional stability.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0043135418309941-fx1.jpg" width="387" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 1 March 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Water Research, Volume 150〈/p〉 〈p〉Author(s): Wangwang Tang, Jie Liang, Di He, Jilai Gong, Lin Tang, Zhifeng Liu, Dongbo Wang, Guangming Zeng〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Substantial consumption and widespread contamination of the available freshwater resources necessitate a continuing search for sustainable, cost-effective and energy-efficient technologies for reclaiming this valuable life-sustaining liquid. With these key advantages, capacitive deionization (CDI) has emerged as a promising technology for the facile removal of ions or other charged species from aqueous solutions via capacitive effects or Faradaic interactions, and is currently being actively explored for water treatment with particular applications in water desalination and wastewater remediation. Over the past decade, the CDI research field has progressed enormously with a constant spring-up of various cell architectures assembled with either capacitive electrodes or battery electrodes, specifically including flow-by CDI, membrane CDI, flow-through CDI, inverted CDI, flow-electrode CDI, hybrid CDI, desalination battery and cation intercalation desalination. This article presents a timely and comprehensive review on the recent advances of various CDI cell architectures, particularly the flow-by CDI and membrane CDI with their key research activities subdivided into materials, application, operational mode, cell design, Faradaic reactions and theoretical models. Moreover, we discuss the challenges remaining in the understanding and perfection of various CDI cell architectures and put forward the prospects and directions for CDI future development.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S004313541830993X-fx1.jpg" width="418" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 1 March 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Water Research, Volume 150〈/p〉 〈p〉Author(s): Fan Zhang, Xiaoxiu Tang, Yuxiong Huang, Arturo A. Keller, Jing Lan〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The competitive removal of Pb〈sup〉2+〈/sup〉 and malachite green (MG) from water by three magnetic phosphate nanocomposites (Fe〈sub〉3〈/sub〉O〈sub〉4〈/sub〉/Ba〈sub〉3〈/sub〉(PO〈sub〉4〈/sub〉)〈sub〉2〈/sub〉, Fe〈sub〉3〈/sub〉O〈sub〉4〈/sub〉/Sr〈sub〉5〈/sub〉(PO〈sub〉4〈/sub〉)〈sub〉3〈/sub〉(OH), and Fe〈sub〉3〈/sub〉O〈sub〉4〈/sub〉/Sr〈sub〉5x〈/sub〉Ba〈sub〉3x〈/sub〉(PO〈sub〉4〈/sub〉)〈sub〉3〈/sub〉(OH), namely “FBP”, “FSP”, and “FSBP”, respectively) was systematically investigated compared with Fe〈sub〉3〈/sub〉O〈sub〉4〈/sub〉 (“F”) nanoparticle. Temperature and adsorbent dosage for competitive removal were optimized to be 20 °C and 0.05 g in 50 mL. The kinetic and isothermal adsorption results were fitted well with the pseudo-second-order model and Langmuir model, respectively. In the competitive removal process, FSP showed a high affinity to Pb〈sup〉2+〈/sup〉 (202.8 mg/g) while FBP possessed high selectivity for MG (175.4 mg/g), and FSBP was effective at simultaneous removal of Pb〈sup〉2+〈/sup〉 and MG, with a capacity of 143.7 and 90.9 mg/g, respectively. The magnetic contents in nanocomposites allow magnetic separation of materials from the water after treatment. We proposed that the simultaneous removal mechanism by FSBP was due to ion exchange between Pb〈sup〉2+〈/sup〉 and Sr〈sup〉2+〈/sup〉 in the lattice and then the formation of hydrogen bonds between PO〈sub〉4〈/sub〉〈sup〉3−〈/sup〉 outside the material's surface and positively charged hydrogen in MG. This study indicates the potential of these phosphate nanocomposites to be used as effective materials for selective or simultaneous removal of Pb〈sup〉2+〈/sup〉 and MG from water.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0043135418309862-fx1.jpg" width="436" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 1 February 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Water Research, Volume 149〈/p〉 〈p〉Author(s): Yubing Ye, Shuili Yu, Li'an Hou, Baosen Liu, Qing Xia, Guicai Liu, Pan Li〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Membrane fouling, especially inorganic fouling due to salt crystal formation and deposition on the membrane surface, is still a major technical issue in membrane distillation (MD) applications. In this study, microbubble aeration (MBA) was included in a laboratory-scale vacuum membrane distillation (VMD) rig and its effect on a desalination process was examined. Without MBA, serious membrane scaling occurred during desalination of simulated high-salinity sea water (100 g.L〈sup〉−1〈/sup〉 salt concentration), which resulted in a dramatic reduction of permeate flux to essentially zero after 120 min. Scanning electron microscopy showed that a layer of large cuboid salt crystals uniformly covered the membrane surface. However, membrane scaling was mitigated with the introduction of MBA, resulting in the improved VMD desalination performance, which was positively correlated with pump pressure in the microbubble (MB) generator. Results showed that the effective processing time of the VMD desalination processing cycle was respectively prolonged to 150, 180, and more than 300 and 360 min (cf. 120 min without MBA) when the pump pressure was respectively at 0.1, 0.2, 0.3 and 0.4 MPa, leading to the increase of cumulative water production. Further studies found that larger numbers of MBs of smaller size were produced at higher pump pressure, which are more beneficial for increasing water vapor production and alleviating salt precipitation. The difference in zeta potential between the MBs in distilled water (about −30 mV) and that in SW100 solution (about -2 mV) demonstrated that MBA not only effectively mitigated the negative effect of concentration polarization by enhancing the surface shear rate at the membrane surface, but also reduced salt precipitation probably due to the MBs attracting counterions to the gas-water interface. Finally, energy consumption analysis of the modified VMD desalination process revealed that MBA, while itself only adding about 3% to the total energy consumption at varied pump pressures, was able to improve the specific energy consumption, especially at higher pump pressures. Together, these results demonstrate that MBA is an effective way of improving the performance of VMD desalination of water.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0043135418309771-fx1.jpg" width="420" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 1 March 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Water Research, Volume 150〈/p〉 〈p〉Author(s): Peiyuan Lin, Xian-Xun Yuan〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Deterioration modelling has been a bottlenecking step towards risk-informed asset management of municipal water distribution networks. To close the gap, we proposed a two-time-scale (TTS) point process model on a pipe level for modelling and prediction of water main breaks. This paper presents the characterization, statistical parameter estimation, probabilistic features, and application of the model. Combining Poisson and renewal models into one, the proposed TTS process is characterized by a conditional intensity function of two time variables—one in a pipe clock for overall pipe aging and the other in a repair clock for local renewal. As a result, different aging patterns including the complicated bathtub-type behaviour can be modelled. A novel statistical method that combines data augmentation and Markov Chain Monte Carlo was developed for model estimation to deal with partially missing event histories. A case study using real-life data collected from a regional municipality in Canada was presented to illustrate the application of the proposed model. The modelling process ranging from model estimation, verification, validation, and updating to application in asset management was thoroughly demonstrated. This study also demonstrated that one must use the full distributions of the parameters to obtain an unbiased prediction of mean number of water main breaks. The proposed model was also compared with the Poisson process model in terms of break intensity, survival probability, mean cumulative number of breaks, and mean annual number of breaks. The implications of the different results to asset management were carefully discussed as well. Last, the ability of the proposed model to capture the maintenance effectiveness of pipe repair was proven. This work represents a solid advancement towards holistic assessment of the aging risk of a municipal water distribution network.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 1 March 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Water Research, Volume 150〈/p〉 〈p〉Author(s): Jiaqi Liu, Xiangru Zhang, Yu Li, Wanxin Li, Chen Hang, Virender K. Sharma〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Flushing toilet with seawater is an effective method for preserving freshwater resources, but it introduces iodide and bromide ions into domestic wastewater. During chlorine disinfection, iodide and bromide ions in the saline wastewater effluent lead to the formation of iodinated and brominated aromatic disinfection byproducts (DBPs). Examples of aromatic DBPs include iodophenolic, bromophenolic and chlorophenolic compounds, which generally display substantially higher toxicity than haloaliphatic DBPs. This paper presented for the first time the rates of phototransformation of 21 newly identified halophenolic DBPs in seawater, the receiving waterbody of the wastewater effluent. The phototransformation rate constants (〈em〉k〈/em〉) were in the range from 7.75 × 10〈sup〉−4〈/sup〉 to 4.62 × 10〈sup〉−1〈/sup〉 h〈sup〉−1〈/sup〉, which gave half-lives of 1.5–895 h. A quantitative structure−activity relationship was established for the phototransformation of halophenolic DBPs as 〈math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si1.gif" overflow="scroll"〉〈mrow〉〈mi〉log〈/mi〉〈mspace width="0.25em"〉〈/mspace〉〈mi〉k〈/mi〉〈mo〉=〈/mo〉〈mspace width="0.25em"〉〈/mspace〉〈mo〉−〈/mo〉〈mn〉0.0100〈/mn〉〈mo〉×〈/mo〉〈mtext〉Δ〈/mtext〉〈msubsup〉〈mrow〉〈mi〉G〈/mi〉〈/mrow〉〈mrow〉〈mi〉f〈/mi〉〈/mrow〉〈mrow〉〈mn〉0〈/mn〉〈/mrow〉〈/msubsup〉〈mo〉+〈/mo〉〈mn〉5.7528〈/mn〉〈mo〉×〈/mo〉〈mi〉log〈/mi〉〈mspace width="0.25em"〉〈/mspace〉〈mi〉M〈/mi〉〈mi〉W〈/mi〉〈mo〉+〈/mo〉〈mn〉0.3686〈/mn〉〈mo〉×〈/mo〉〈mi〉p〈/mi〉〈mi〉K〈/mi〉〈mi〉a〈/mi〉〈mo〉−〈/mo〉〈mn〉19.1607〈/mn〉〈/mrow〉〈/math〉, where ΔG〈sub〉f〈/sub〉〈sup〉0〈/sup〉 is standard Gibbs formation energy, MW is molecular weight, and pK〈sub〉a〈/sub〉 is dissociation constant. This model well predicted the 〈em〉k〈/em〉 values of halophenolic DBPs. Among the tested DBPs, 2,4,6-triiodophenol and 2,6-diiodo-4-nitrophenol were found to exhibit relatively high risks on marine organisms, based on toxicity indices and half-lives. In seawater, the two DBPs underwent photonucleophilic substitutions by bromide, chloride and hydroxide ions, resulting in the conversion to their bromophenolic and chlorophenolic counterparts (which are less toxic than the parent iodophenolic DBPs) and to their hydroxyphenolic counterparts (iodo(hydro)quinones, which are more toxic than the parent iodophenolic DBPs). The formed iodo(hydro)quinones further transformed to hydroxyl-iodo(hydro)quinones, which have lower toxicity than the parent compounds.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0043135418309886-fx1.jpg" width="303" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 5 February 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Applied Thermal Engineering, Volume 148〈/p〉 〈p〉Author(s): Jie Zhao, Da-Zhong Yuan, Da-Wei Tang, Yu-Yan Jiang〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Many industrial applications call for high-temperature heat pipes working in anti-gravity modes. In past studies, heat pipes with concentric annular structures were developed with certain levels of anti-gravity working ability in low-temperature ranges. In this study, a concentric annular high-temperature heat pipe (CAHTHP) used for anti-gravity operation was designed and fabricated. Under the anti-gravity working condition, the effects of inclination angle on the CAHTHP frozen startup performance and temperature uniformity were experimentally studied and compared with gravity-operated experiments. The results show that the CAHTHP can achieve stable anti-gravity operation under high flux heating and natural convection cooling. The anti-gravity working condition and the working inclination angle have slight effects on the frozen startup rapidity and temperature uniformity of the CAHTHP. For different inclination angles, the CAHTHP startup times are all similar at approximately 450 s, and the thermal resistance values are all smaller than 0.05 °C/W. Moreover, the anti-gravity frozen startup process variation of the CAHTHP is in good agreement with that of the frozen startup two-region model.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 5 February 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Applied Thermal Engineering, Volume 148〈/p〉 〈p〉Author(s): Mohamad Sadeq Karimi, Saeed Salehi, Mehrdad Raisee, Patrick Hendrick, Ahmad Nourbakhsh〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The stochastic computations of a NASA gas turbine vane are conducted to investigate the effects of the operational uncertainties on the flow and heat transfer characteristics of the NASA C3X blade. The blade contains ten internal cooling channels to remove heat load. In order to minimize the analysis error the full conjugate heat transfer methodology has been employed to simulate the behavior of external hot gas flows, internal cooling air passages and the solid blade simultaneously. The 〈math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si18.gif" overflow="scroll"〉〈mrow〉〈msup〉〈mrow〉〈mi〉v〈/mi〉〈/mrow〉〈mrow〉〈mn〉2〈/mn〉〈/mrow〉〈/msup〉〈mo〉-〈/mo〉〈mi〉f〈/mi〉〈/mrow〉〈/math〉 turbulence model is used and it is shown the predicted results are in acceptable agreement with the available experimental data. Total pressure, total temperature, turbulence intensity, turbulent length-scale of the inlet and the outlet static pressure are assumed to be stochastic with Beta probability distribution functions. The effects of these uncertainties on flow and thermal fields as well as the blade temperature distribution are studied. The polynomial chaos method with polynomials order 〈math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si19.gif" overflow="scroll"〉〈mrow〉〈mi〉p〈/mi〉〈mo〉=〈/mo〉〈mn〉3〈/mn〉〈/mrow〉〈/math〉 is used to quantify the effects of operational uncertainties. The non-deterministic CFD results are found to be in close agreement with the experimental data. Uncertainties specially in inlet total temperature and turbulent length-scale play key roles on the hydrodynamic and thermal fields around the airfoil also the turbine vane temperature distribution.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 5 February 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Applied Thermal Engineering, Volume 148〈/p〉 〈p〉Author(s): Jinlong Xie, Hsiao Mun Lee, Jianhua Xiang〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Embedding metal fins into PCMs to improve the thermal conductance of PCM enclosure is widely used in the thermal management of mobile electronics. This paper presented the application of a density-based structure optimization method to redesign the conductive metal structure for better heat diffusion from a concentrated heat source into a PCM enclosure. Two plate fin heat sink structured PCM enclosures with the metal volume fractions of 20% and 30% were the baselines, and the optimized tree shape structures with the similar metal volume fractions of 18.7% and 27.6% were generated for comparison. A transient numerical model based on the Volume of Fluid (VOF) and enthalpy-porosity methods was built to investigate the dynamic thermal behaviors of PCM enclosures. Results illustrated that the optimized tree shape designs outperformed the baseline designs by achieving lower heat source temperature and higher melt fraction in the main PCM melting stage. Increasing metal volume fraction improved the overall thermal conductance of PCM enclosures and hence suppressed the temperature non-uniformity and lowered the heat source temperature. Upwardly orientated PCM enclosure had much better heat transfer performance than that under downward orientation due to its enhanced thermal mixing resulted from the intensified convection flows.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 25 February 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Applied Thermal Engineering, Volume 149〈/p〉 〈p〉Author(s): Bin Chen, Li Zhang, Jinlin Han, Xi Chen〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Adding water to the intake air of gasoline engines efficiently improves operations and is highly influential to knock occurrence and NOx emissions. These factors largely benefit from the high latent heat of vaporization as well as the high specific heat of water. In this paper, based on a 1.5 L turbocharged gasoline direct injection engine, those impacts were deeply studied by separating the effect of charge cooling from the influence of increasing specific heat. An experimental test was undertaken to validate the effect of water introduction on the basic engine as well as to confirm boundary conditions and basic parameters for numerical analysis which was based on Ricardo WAVE code. Results indicate that the water introduction technique did improve engine output and thermal efficiency. Engine operations however, were primarily influenced by the impact of increasing specific heat. The charge cooling effect merely reduced the intake air temperature and had a minor impact on in-cylinder thermodynamics. Findings show the impact of water introduction on knock occurrence, engine output, thermal efficiency, and reduction in NOx emissions were mainly boosted by enhancing the specific heat of the operating medium and the effect of charge cooling was found to be insignificant.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 25 February 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Applied Thermal Engineering, Volume 149〈/p〉 〈p〉Author(s): Zehui Shao, Ehsan Gholamalizadeh, Albert Boghosian, Behnam Askarian, Zhenling Liu〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉One of the main challenges in multi-chill system issues by considering the uncertainty of cooling demand is total energy consumed and energy buying cost. Therefore, it is necessary to optimize power consumption in these issues. This paper provides a robust optimization method with uncertainty modeling in multi-chiller systems to obtain accurate planning. It should be noted that one of the energy supply sources for multi chiller system is photovoltaic system (in addition to the network). In order to improve cooling demand profile, using demand response program, demand levels are shifted through peak periods of energy consumption to low consumption periods. In this work, the minimization of energy procurement cost of multi-chiller systems from the upstream network is assumed as a target function, taking into account demand response of cooling and uncertainty demand. Also, the effect of cooling demand response on two robust and deterministic strategies has been investigated. Achieved results depict, risk-averse method through robust method is robust against cooling requirement uncertainty, contrasting to risk-neutral method through deterministic approach. In addition, the cost of supplying energy of multi-chiller systems from solar systems is reduced by using the demand response program in both of mentioned methods.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 March 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Water Research, Volume 151〈/p〉 〈p〉Author(s): Xianwei Wu, Ju Huang, Zichuan Lu, Gaofeng Chen, Jianmin Wang, Guoqiang Liu〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉This study revealed that, 〈em〉Thiothrix eikelboomii〈/em〉, a well-known filamentous bacterium that causes sludge bulking, could also interfere oxygen transfer during wastewater treatment. The volumetric oxygen transfer coefficient (K〈sub〉L〈/sub〉a) in filamentous-bulking sludge (FBS) was found to be 43% lower than that in floc-forming sludge (FFS) at similar biomass concentrations, partially because the filamentous bacteria had increased the sludge apparent viscosity. The K〈sub〉L〈/sub〉a value for FBS, however, was still significantly lower than that for FFS even if both sludges had similar apparent viscosity. Numerous tiny and free-swimming filaments were observed to attach on the air bubble surface, presumably reducing the liquid film renewal and increasing the liquid film thickness. Moreover, the filaments were co-coated with extracellular polymeric substances of protein and polysaccharide, which could make them performing like “amphiphilic molecules” of surfactants to hinder oxygen transfer. Therefore, the particular surface property of filaments and their interaction with air bubbles could also impact oxygen transfer. 〈em〉Thiothrix eikelboomii〈/em〉 was identified to be the responsible filamentous bacterium that lowered the K〈sub〉L〈/sub〉a value, while other filamentous bacteria with short filaments did not interfere oxygen transfer. This study implies that controlling sludge bulking benefits not only sludge settling but also oxygen transfer.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0043135418310364-fx1.jpg" width="500" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 15 March 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Water Research, Volume 151〈/p〉 〈p〉Author(s): Hannah R. Safford, Heather N. Bischel〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Ensuring safe and effective water treatment, distribution, and reuse requires robust methods for characterizing and monitoring waterborne microbes. Methods widely used today can be limited by low sensitivity, high labor and time requirements, susceptibility to interference from inhibitory compounds, and difficulties in distinguishing between viable and non-viable cells. Flow cytometry (FCM) has recently gained attention as an alternative approach that can overcome many of these challenges. This article critically and systematically reviews for the first time recent literature on applications of FCM in water treatment, distribution, and reuse. In the review, we identify and examine nearly 300 studies published from 2000 to 2018 that illustrate the benefits and challenges of using FCM for assessing source-water quality and impacts of treatment-plant discharge on receiving waters, wastewater treatment, drinking water treatment, and drinking water distribution. We then discuss options for combining FCM with other indicators of water quality and address several topics that cut across nearly all applications reviewed. Finally, we identify priority areas in which more work is needed to realize the full potential of this approach. These include optimizing protocols for FCM-based analysis of waterborne viruses, optimizing protocols for specifically detecting target pathogens, automating sample handling and preparation to enable real-time FCM, developing computational tools to assist data analysis, and improving standards for instrumentation, methods, and reporting requirements. We conclude that while more work is needed to realize the full potential of FCM in water treatment, distribution, and reuse, substantial progress has been made over the past two decades. There is now a sufficiently large body of research documenting successful applications of FCM that the approach could reasonably and realistically see widespread adoption as a routine method for water quality assessment.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0043135418310339-fx1.jpg" width="285" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 15 March 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Water Research, Volume 151〈/p〉 〈p〉Author(s): Long T. Ho, Andres Alvarado, Josue Larriva, Cassia Pompeu, Peter Goethals〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Imitating natural lakes, pond treatment systems inherit a high complexity with interconnected web of biochemical reactions and complex hydraulic processes. As such, its simulation requires a large and integrated model, which has been a challenge for pond engineers. In this study, we develop an all-encompassing model to gain a quantitative and comprehensive understanding of the hydraulic, physicochemical and microbiological conversion processes in the most common pond, a facultative pond. Moreover, to deal with an evitable issue of large mechanistic models as overparameterization leading to poor identifiability, a systematic parameter estimation was implemented. The application of sensitivity analysis reveals the most influential parameters on pond performance. Particularly, physical parameters, such as vertical eddy diffusivity, water temperature, and maximum growth rate of heterotrophs induce the most changes of organic matters while microbial assimilation and ammonia volatilization appear to be main processes for nutrient removal. In contrast, the efficiency of phosphate precipitation and nutrient biological removal via polyphosphate accumulating organisms and denitrifying bacteria is limited. Identifiability problems are addressed mainly by the characterization of light dependence of algal growth, interaction between water temperature and its coefficient, and the growth of autotrophic bacteria while based on the determinant measures, the most important parameter subsets affecting model outputs are related to physical processes and algal activity. After the establishment of the influential and identifiable parameter subset, an automatic calibration with the data collected from Ucubamba pond system (Ecuador) demonstrates the effect of high-altitude climatic conditions on pond behaviors. An aerobic prevailing condition is observed as a result of high light intensity causing accelerated algal activities, hence, leading to the limitation of hydrolysis, anaerobic processes, and the growth of anoxic heterotrophs for denitrification. Furthermore, the output of uncertainty analysis indicates that a large avoidable uncertainty as a result of vast complexity of the applied model can be reduced greatly via a systematic approach for parameter estimation.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0043135418310352-fx1.jpg" width="473" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 5 February 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Applied Thermal Engineering, Volume 148〈/p〉 〈p〉Author(s): M.K. Parida, H. Joardar, A.K. Rout, I. Routaray, B.P. Mishra〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The characteristics of multi-fuel VCR engine fuelled with Argemone Mexicana methyl ester, prepared by two step trans-esterification process and its diesel blends (20%, 40%, 60% and 100%) were evaluated with variation of load (3–12 kg) and compression ratio (16–18). In the current analysis engine load, compression ratio and biodiesel blends were taken as input parameters. Response Surface Methodology of Full Factorial Design was used for modelling and analyzing the response parameters with Minitab-14.0 software. Data regression, significance analysis and individual model coefficients were studied for the developed models and presented for validation of the model. Multi objective optimization was carried out for the responses by using the desirability function. Confirmation experiments were executed for validation of optimization results by setting input parameters (Load = 9.8 kg, CR = 18.0, Blend = 20%). Output responses from the mathematical modeling such as BTE 26.77%, BSFC 0.284 kg/kW h, CO 0.0059%, HC 114.84 ppm, NO〈sub〉x〈/sub〉 905.6 ppm respectively were obtained using D-optimal test with composites desirability of 0.97009. The predictions of RSM results were obtained in concurrence with the experimental ones, with errors less than 5% excepting for CO model.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 25 February 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Applied Thermal Engineering, Volume 149〈/p〉 〈p〉Author(s): Saeed Mahdavi, Faramarz Sarhaddi, Mahdi Hedayatizadeh〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Through the present paper, a solar greenhouse integrated with an Earth-Air Heat Exchanger (EAHE) and Photovoltaic/Thermal collectors (PV/Ts) was theoretically studied in terms of energy and exergy and validated against an experimental study presented in literature i.e. a solar greenhouse with floor area, buried pipe length and PV area of 24 m〈sup〉2〈/sup〉, 39 m and 9.68 m〈sup〉2〈/sup〉, respectively. The comparisons showed a fairly good agreement between the theoretical and experimental results with a relatively high coefficient of correlation around 95%. Afterwards, the given solar greenhouse was optimized in terms of energy and exergy efficiencies while the results indicated that only length of EAHE pipes showed an optimum value equal to 38 m on average. Moreover, the results showed that PV/Ts did not have a significant heating potential for raising the greenhouse air and plant temperatures and only the electricity generation potential of PVs was favorable. However, the EAHE integration seemed promising in raising and lowering the temperatures of greenhouse air by 9 °C and 8 °C in summer and winter, respectively. Moreover, the Temperature Load Leveling (TLL) due to integration of only EAHE was achieved 46% and 58% in summer and winter, respectively.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 25 February 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Applied Thermal Engineering, Volume 149〈/p〉 〈p〉Author(s): Afshin Najafi-Ghalelou, Sayyad Nojavan, Kazem Zare, Behnam Mohammadi-Ivatloo〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Multi-carrier hub energy system (MCHES) satisfies different energy demands such as heating, cooling, and energy demand by using different energy sources simultaneously. In this paper, a robust optimization approach (ROA) is provided for robust scheduling of MCHES considering economic and environmental constraints in the presence of market price uncertainty and multi-demand response programs (DRPs). In ROA, lower and upper levels of market price are considered instead of forecasted market price which guarantees the robust scheduling of the MCHES. The time-of-use (TOU) and real-time-pricing (RTP) rates of DRPs play a vital role in flattening the load curve with the aim of reducing the total operation cost and CO〈sub〉2〈/sub〉 emission. The proposed model is formulated as robust mixed integer linear programming (RMILP) and solved by General Algebraic Modeling System (GAMS) platform which has a great advantage in solving the linear programming models. Finally, to assess the effects of assumed DRPs on robust scheduling of MCHES, three case studies are utilized, and significant results were obtained.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 25 February 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Applied Thermal Engineering, Volume 149〈/p〉 〈p〉Author(s): Guo-Hua Shi, Lu Aye, Rui Dai, Xian-Jun Du, Jiang-Jiang Wang〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉This study investigated a novel LPG vaporisation system utilising direct-expansion solar-assisted heat pump (DX-SAHPV)〈sup〉1〈/sup〉 for supplying residential gas. The DX-SAHPV applies a collector-evaporator to obtain heat energy from both solar radiation and ambient air to produce hot water to vaporise LPG liquid. It can operate in six operating modes depending on the weather and gas load conditions. In this study, a dynamic model and control strategies realising the mode switching were developed to carry out the operating performance evaluation of the system. By applying the typical meteorological year data and the gas load data of a community in Beijing, China, the performance of the DX-SAHPV was evaluated and analysed for the whole year and two selected days. The simulation results show that the system can vaporise adequate LPG liquid for the community throughout the year. The solar energy contribution accounts for approximately 68% of the total heat energy for the water heated vaporisation. It was also found that the DX-SAHP obtains average monthly values of COP ranging from 2.72 to 3.37 and solar collector efficiency varying between 93 and 152%. In addition, which mode the system operates at any time on selected days was predicted and the running time of each mode in each month was discussed.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 March 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Water Research, Volume 151〈/p〉 〈p〉Author(s): Ming Zheng, Yongmei Li, Qian Ping, Lin Wang〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Medium-pressure ultraviolet light (MP-UV) combined with calcium peroxide (CaO〈sub〉2〈/sub〉) as a pretreatment technology for removing carbamazepine (CBZ) and primidone (PMD) in waste active sludge (WAS) and improving the solubilization of sludge were investigated. CBZ and PMD were effectively removed and the removal fitted pseudo-first kinetics under MP-UV/CaO〈sub〉2〈/sub〉 treatment with R〈sup〉2〈/sup〉 〉 0.97. The higher CaO〈sub〉2〈/sub〉 dosage and lower initial volatile suspended solids (VSS) concentration were conductive to the removal of CBZ and PMD. Of the CaO〈sub〉2〈/sub〉 hydrolysates, Ca(OH)〈sub〉2〈/sub〉 played a more important role than H〈sub〉2〈/sub〉O〈sub〉2〈/sub〉 during MP-UV/CaO〈sub〉2〈/sub〉 treatment. The removal of the target compounds was attributed to direct photolysis and indirect photolysis caused by •OH, 〈sup〉3〈/sup〉DOM〈sup〉*〈/sup〉, and 〈sup〉1〈/sup〉O〈sub〉2〈/sub〉, in which •OH played a vital role with 〉 62.2% contribution to the overall degradation rate. A model predicting the steady concentration of •OH in WAS ([VSS] ≈ 8.6 g L〈sup〉−1〈/sup〉) under MP-UV/CaO〈sub〉2〈/sub〉 treatment with CaO〈sub〉2〈/sub〉 dosage ranging from 0 to 0.5 g g〈sup〉−1〈/sup〉-VSS was proposed and validated. Moreover, major intermediates of CBZ and PMD were detected and the probable transformation pathways during MP-UV/CaO〈sub〉2〈/sub〉 treatment were proposed. In addition, MP-UV/CaO〈sub〉2〈/sub〉 promoted the sludge solubilization effectively. Considering both the pharmaceutical degradation and sludge solubilization, the optimum operation condition with 0.2 g-CaO〈sub〉2〈/sub〉 g〈sup〉−1〈/sup〉-VSS combined with 7 h MP-UV irradiation is recommended. Under this condition, more than 92.3% of CBZ and 90.3% of PMD were removed, and soluble chemical oxygen demand (SCOD) increased by 657% and 13.6% compared with sole 10 h CaO〈sub〉2〈/sub〉 (0.2 g g〈sup〉−1〈/sup〉-VSS) treatment and 7 h MP-UV treatment, respectively.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0043135418310273-fx1.jpg" width="500" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 5 February 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Applied Thermal Engineering, Volume 148〈/p〉 〈p〉Author(s): T. Arunkumar, D. Murugesan, Kaiwalya Raj, David Denkenberger, C. Viswanathan, D. Dsilva Winfred Rufuss, R. Velraj〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Nanostructured Copper Oxide (CuO) is coated on the stainless steel (SS) 316 substrates using thermal evaporation method. The effect of CuO nanostructured coated absorber plates (NCAP) integrated with Polyvinyl Alcohol (PVA) sponges is investigated in a single slope solar still (SSSS) for desalination. The experiment was conducted in the following configurations: (1) SSSS alone, (2) SSSS with CuO-NCAP, (3) SSSS with PVA sponges and (4) SSSS-CuO-NCAP with PVA sponges. Four identical SSSSs were built with 0.50 m〈sup〉2〈/sup〉 collector area and tested under the same climatic conditions of Chennai, India during the period of March to April 2018. The CuO coated on the SS316 was characterized by Grazing Incidence X-ray Diffraction (GIXRD), Field emission Scanning Electron Microscope (FESEM) and Energy Dispersive Spectrum (EDS). The climatic parameters like ambient temperature, solar radiation and internal temperatures of the SSSS were measured at frequent intervals of time. The efficiencies of the SSSS, SSSS-CuO-NCAP, SSSS-PVA sponges and SSSS with CuO-NCAP-PVA sponges are 37%, 53%, 32% and 41% respectively. The productivity of SSSS, SSSS-CuO-NCAP, SSSS-PVA sponges and SSSS with CuO-NCAP-PVA sponges are 2144 ml/m〈sup〉2〈/sup〉/day, 2995 ml/m〈sup〉2〈/sup〉/day, 1970 ml/m〈sup〉2〈/sup〉/day, and 2318 ml/m〈sup〉2〈/sup〉/day, respectively. Therefore, the addition of the sponges was counterproductive, but the CuO-NCAP significantly increased output.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 5 February 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Applied Thermal Engineering, Volume 148〈/p〉 〈p〉Author(s): Joon Ha Lee, Dae Hae Kim, Seong Min Kim, Min Soo Kim, In Gwan Kim, Sung Min Woo, Sung Joo Hong, Chan Woo Park〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉A generator is a heart of an absorption refrigeration system. It plays a significant role in the operation cycle by desorbing the water vapor from a lithium bromide (LiBr) solution. The wettability of the solution over the heating tubes has been considered for heat transfer enhancement in a water-LiBr falling film generator. This paper proposes seven types of heating tube bundles modified by surface treatments to improve the wettability. Each heating tube bundle was installed in the falling film generator for each experimental set, and the heat transfer characteristics were observed to evaluate the shell side heat transfer coefficients. Experiments were carried out with the following operating conditions: feed solution temperature (63.5 °C), solution flow rate (4–9 kg/min), feed solution concentration (55–58%), and pressure at the shell side (4.7–6.7 kPa). Hot water was used as a heat source, and the operating parameters were the feed temperature (85–97 °C) and the flow rate (10–28 L per minute). Each heating tube bundle had entirely different heat transfer characteristics, which were distinctly illuminated. The experimental correlations for a shell side heat transfer were developed to estimate the real benefits of using the proposed heating tube bundles. All the obtained empirical correlations were validated within an error limit of around ±20%.〈/p〉〈/div〉 〈/div〉