ALBERT

Description: Present challenges for future water sustainable cities: a case study from Italy L. Bonzanigo and G. Sinnona Drink. Water Eng. Sci., 7, 35-40, doi:10.5194/dwes-7-35-2014, 2014 The global population is increasingly concentrated in cities. Cities and urban areas face many challenges – economic, social, health and environmental – which are often exacerbated by an increase in the frequency of natural disasters. Together, these challenges call for a shift towards sustainable cities which reduce their impact on the surrounding environment, whilst at the same time succeeding to make resources available to their increasing number of inhabitants. This study explores the state of the art of water management practices of the highly urbanised Northern Italian region and plans and scope for the future development of water management. Although the region is at present not under severe water stress, recently some cities faced water scarcity problems and were forced to implement water rationing. We assessed the vulnerability of Parma and Ferrara to a water crisis, together with the regular and emergency adaptation measures already in place, and the forecast for the near future. In two workshops, the authors adapted the Australian concept of water sensitive urban design for the Italian context. Although the population remains generally unaware of the impact of the two latest severe drought events (2003 and 2006/7), many adaptation measures towards a more sustainable use of the water resource are already in place – technically, institutionally, and individually. Water managers consider however that the drastic and definite changes needed to integrate the urban water management cycle, and which minimise the ecological footprint of urban spaces, lay far in the future.

Description: Nanofiltration for water and wastewater treatment – a mini review Drinking Water Engineering and Science, 6, 47-53, 2013 Author(s): H. K. Shon, S. Phuntsho, D. S. Chaudhary, S. Vigneswaran, and J. Cho The application of membrane technology in water and wastewater treatment is increasing due to stringent water quality standards. Nanofiltration (NF) is one of the widely used membrane processes for water and wastewater treatment in addition to other applications such as desalination. NF has replaced reverse osmosis (RO) membranes in many applications due to lower energy consumption and higher flux rates. This paper briefly reviews the application of NF for water and wastewater treatment including fundamentals, mechanisms, fouling challenges and their controls.

Description: Application of DVC-FISH method in tracking Escherichia coli in drinking water distribution networks Drinking Water Engineering and Science, 6, 25-31, 2013 Author(s): L. Mezule, S. Larsson, and T. Juhna Sporadic detection of live (viable) Escherichia coli in drinking water and biofilm with molecular methods but not with standard plate counts has raised concerns about the reliability of this indicator in the surveillance of drinking water safety. The aim of this study was to determine spatial distribution of different viability forms of E. coli in a drinking water distribution system which complies with European Drinking Water Directive (98/83/EC). For two years coupons (two week old) and pre-concentrated (100 times with ultrafilters) water samples were collected after treatment plants and from four sites in the distribution network at several distances. The samples were analyzed for total, viable (able to divide as DVC-FISH positive) and cultivable E. coli . The results showed that low numbers of E. coli enters the distribution sytem from the treatment plants and tend to accumulate in the biofilm of water distribution system. Almost all of the samples contained metabolically active E. coli in the range of 1 to 50 cells per litre or cm 2 which represented approximately 53% of all E. coli detected. The amount of viable E. coli significantly increased into the network irrespective of the season. The study has shown that DVC-FISH method in combination with water pre-concentration and biofilm sampling allows to better understand the behaviour of E. coli in water distribution networks, thus, it provides new evidences for water safety control.

Description: Stored-heat assessments: a review in the light of field experience Geothermal Energy Science, 2, 49-54, 2014 Author(s): M. A. Grant Stored-heat or volumetric assessments of geothermal resources are appealingly simple: the resource being exploited is heat. A stored-heat calculation simply computes the amount of heat in the resource, similarly to computing the amount of ore in an ore body. The method has theoretical support in numerical simulations of resource production. While there are significant unknowns in any resource, some of these can be covered by probabilistic approaches, notably a Monte Carlo method. The Australian Geothermal Reporting Code represents one specification of such stored-heat assessments. However the experience of recent decades, with the development of significant numbers of geothermal resources, has shown that the method is highly unreliable and usually biased high. The tendency to overestimates, in particular, has led to the reduced credibility of the method. An example is quoted where simple application of the apparently simple rules gives a ridiculous result. Much of the problem lies in the "recovery factor", the proportion of the resource that can actually be exploited, where comparison with actual performance shows past values have been in all cases too high, as is the current version of the Australian code. There are further problems, usually overlooked, in the way that the reservoir volume and "cutoff temperature" are defined. Differing approaches mean that results between different reports are not comparable. The different approaches also imply unrecognised assumptions about the physical processes controlling reservoir depletion. The failure of Monte Carlo methods is similarly due to unrecognised violation of logical consistency in the use of probabilities. The net effect of these problems is that the method is not a simple means to generate a rough resource estimate, and it often generates faulty results. Usually, such results are overestimates. Monte Carlo methods do not provide a protection against these errors. The Australian Geothermal Reporting Code should be used for hydrothermal systems with an average recovery factor of 10%. With this average, results are subject to an error of ±70%. For enhanced geothermal systems (EGS), the recovery factor should be a few percent.

Description: Feasibility assessment of household based small arsenic removal technologies for achieving sustainable development goals Md Sahadat Hossain, Fahima Akhter, and Victor Emery David Jr Drink. Water Eng. Sci. Discuss., doi:10.5194/dwes-2016-1,2016 Manuscript under review for DWES (discussion: open, 0 comments) Sustainability is a complex multi-functional approach & arsenic poisoning is a socio-political important issue for achieving SDGs in drinking sector of Bangladesh. This societal need has introduced small technologies those are helping rural poor peoples for accessing to safe drinking water. However, managing the generated arsenic-laden has been avoiding since very beginning. In this vein, this study is proposing a framework for analyzing & achieving long-term sustainability in this sector.

Description: Feasibility assessment of household based small arsenic removal technologies for achieving sustainable development goals Md Sahadat Hossain, Fahima Akhter, and Victor Emery David Jr Drink. Water Eng. Sci. Discuss., doi:10.5194/dwes-2016-1,2016 Manuscript under review for DWES (discussion: open, 0 comments) Sustainability is a complex multi-functional approach & arsenic poisoning is a socio-political important issue for achieving SDGs in drinking sector of Bangladesh. This societal need has introduced small technologies those are helping rural poor peoples for accessing to safe drinking water. However, managing the generated arsenic-laden has been avoiding since very beginning. In this vein, this study is proposing a framework for analyzing & achieving long-term sustainability in this sector.

Description: 〈b〉Optimization shallow groundwater quality by the application of photocatalysis treatment technique in El Obour city, Egypt〈/b〉〈br〉 El-Montser M. Seleem, Hossam A. El Nazer, Salah A. M. Zeid, Salman A. Salman, and Mahmoud A. Abdel-Hafiz〈br〉 Drink. Water Eng. Sci. Discuss., https//doi.org/10.5194/dwes-2018-41,2018〈br〉 〈b〉Revised manuscript under review for DWES〈/b〉 (discussion: final response, 7 comments)〈br〉 〈p〉Collection of shallow groundwater and injecting it into the underline Miocene aquifer is a great environmental problem on the groundwater resources at El Obour city and environs. The present research work aims to investigate this water quality and validity of photocatalytic treatment of polluted water using nano-titania in presence of solar radiation. Twenty-eight representative samples were collected from various locations and their physical, chemical and microbial characteristics were determined. Bacteria analysis has been investigated for the presence of total bacterial count and indicator bacteria include total coliform, fecal coliform and fecal streptococci. The heavy metal analysis shows that more than 85 % of the samples could be used for drinking in comparison with WHO specification for drinking water. The main pollutants in these samples are Cd and Pb. All the studied samples contain a viable count of heterotrophic bacteria, total coliform, fecal coliform and fecal streptococci, indicating the contamination with human and animal fecal material. The high number of indicator microorganism counts observed reflected the poor quality of water. The photocatalytic technique shows high efficiency towards the removal of more than 95 % and 82 % of microbial pollutants and organic residuals; respectively.〈/p〉

Description: 〈b〉Optimization shallow groundwater quality by the application of photocatalysis treatment technique in El Obour city, Egypt〈/b〉〈br〉 El-Montser M. Seleem, Hossam A. El Nazer, Salah A. M. Zeid, Salman A. Salman, and Mahmoud A. Abdel-Hafiz〈br〉 Drink. Water Eng. Sci. Discuss., https//doi.org/10.5194/dwes-2018-41,2018〈br〉 〈b〉Revised manuscript under review for DWES〈/b〉 (discussion: final response, 7 comments)〈br〉 〈p〉Collection of shallow groundwater and injecting it into the underline Miocene aquifer is a great environmental problem on the groundwater resources at El Obour city and environs. The present research work aims to investigate this water quality and validity of photocatalytic treatment of polluted water using nano-titania in presence of solar radiation. Twenty-eight representative samples were collected from various locations and their physical, chemical and microbial characteristics were determined. Bacteria analysis has been investigated for the presence of total bacterial count and indicator bacteria include total coliform, fecal coliform and fecal streptococci. The heavy metal analysis shows that more than 85 % of the samples could be used for drinking in comparison with WHO specification for drinking water. The main pollutants in these samples are Cd and Pb. All the studied samples contain a viable count of heterotrophic bacteria, total coliform, fecal coliform and fecal streptococci, indicating the contamination with human and animal fecal material. The high number of indicator microorganism counts observed reflected the poor quality of water. The photocatalytic technique shows high efficiency towards the removal of more than 95 % and 82 % of microbial pollutants and organic residuals; respectively.〈/p〉

Description: 〈b〉Evaluation of human risks of surface and groundwater contaminated with Cd and Pb south of El-Minya Governorate, Egypt〈/b〉〈br〉 Salman Salman, Ahmed A. Asmoay, Amr El-Gohary, and Hassan Sabet〈br〉 Drink. Water Eng. Sci. Discuss., https//doi.org/10.5194/dwes-2018-37,2018〈br〉 〈b〉Revised manuscript under review for DWES〈/b〉 (discussion: final response, 10 comments)〈br〉 55 samples of water were investigated and the results revealed that cd and pb content exceeded the allowable level for drinking water. Also, they have a health risk to residents.

Description: 〈b〉Evaluation of human risks of surface and groundwater contaminated with Cd and Pb south of El-Minya Governorate, Egypt〈/b〉〈br〉 Salman Salman, Ahmed A. Asmoay, Amr El-Gohary, and Hassan Sabet〈br〉 Drink. Water Eng. Sci. Discuss., https//doi.org/10.5194/dwes-2018-37,2018〈br〉 〈b〉Revised manuscript under review for DWES〈/b〉 (discussion: final response, 10 comments)〈br〉 55 samples of water were investigated and the results revealed that cd and pb content exceeded the allowable level for drinking water. Also, they have a health risk to residents.

Description: Water Expert : a conceptualized framework for development of a rule-based decision support system for distribution system decontamination Drinking Water Engineering and Science, 8, 9-24, 2015 Author(s): J. L. Gutenson, A. N. S. Ernest, J. R. Fattic, L. E. Ormsbee, A. A. Oubeidillah, and X. Zhang Significant drinking water contamination events pose a serious threat to public and environmental health. Water utilities often must make timely, critical decisions without evaluating all facets of the incident. The data needed to enact informed decisions are inevitably dispersant and disparate, originating from policy, science, and heuristic contributors. Water Expert is a functioning hybrid decision support system (DSS) and expert system framework that emphasizes the meshing of parallel data structures in order to expedite and optimize the decision pathway. Delivered as a thin-client application through the user's web browser, Water Expert 's extensive knowledgebase is a product of inter-university collaboration that methodically pieced together system decontamination procedures. Decontamination procedures are investigated through consultation with subject matter experts, literature review, and prototyping with stakeholders. This paper discusses the development of Water Expert , analyzing the development process underlying the DSS and the system's existing architecture specifications. Water Expert constitutes the first system to employ a combination of deterministic and heuristic models which provide decontamination solutions for water distribution systems. Results indicate that the decision making process following a contamination event is a multi-disciplinary effort. This contortion of multiple inputs and objectives limit the ability of the decision maker to find optimum solutions without technological intervention.

Description: Do low-cost ceramic water filters improve water security in rural South Africa? Jens Lange, Tineke Materne, and Jörg Grüner Drink. Water Eng. Sci. Discuss., doi:10.5194/dwes-2016-6,2016 Manuscript under review for DWES (discussion: open, 0 comments) Here we investigate the suitability of a specific low-cost water filter for drinking water treatment in households of rural South Africa. Distributed in the field, none of 51 individually tested water filters produced water without distinct contamination and more than one third even deteriorated hygienic water quality. We therefore recommend frequent monitoring of the filter performance at the point of use and identified dip slides as an efficient tool to assess critical contamination.

Description: Do low-cost ceramic water filters improve water security in rural South Africa? Jens Lange, Tineke Materne, and Jörg Grüner Drink. Water Eng. Sci. Discuss., doi:10.5194/dwes-2016-6,2016 Manuscript under review for DWES (discussion: open, 0 comments) Here we investigate the suitability of a specific low-cost water filter for drinking water treatment in households of rural South Africa. Distributed in the field, none of 51 individually tested water filters produced water without distinct contamination and more than one third even deteriorated hygienic water quality. We therefore recommend frequent monitoring of the filter performance at the point of use and identified dip slides as an efficient tool to assess critical contamination.

Description: Geochemical study on hot-spring water in West New Britain Province, Papua New Guinea Geothermal Energy Science, 3, 61-67, 2015 Author(s): M. M. Lahan, R. T. Verave, and P. Y. Irarue West New Britain Province, which occupies the western part of New Britain Island in Papua New Guinea, is ideally located within an active tectonic region that influences volcanism creating an environment favourable for geothermal activity. Geothermal mapping of surface manifestations reveals high temperature geothermal prospects along the northern coastline of West New Britain Province that are further confirmed by geochemical analysis. The occurrence of geothermal features is confined to the Quaternary Kimbe Volcanics and alluvium in the lowland areas. The features in Talasea appear to be controlled by deep-seated northerly trending faults while structures in Hoskins also appear to be deep seated but have not been identified. The geothermal systems in West New Britain Province have not been drilled, but preliminary reconnaissance geothermal mapping and geochemical analysis reveals four high temperature geothermal prospects suitable for further investigation and development of geothermal energy. These are the Pangalu (Rabili) and Talasea Station geothermal prospects in Talasea and Kasiloli (Magouru) and Silanga (Bakama and Sakalu) geothermal prospects in Hoskins. The calculated reservoir temperatures for these fields are in the range of 245–310 °C. Recommendations are made for further follow-up exploratory investigations.

Description: Estimating fast and slow reacting component in surface and groundwater using 2R model Drinking Water Engineering and Science Discussions, 8, 197-217, 2015 Author(s): P. Jamwal, M. N. Naveen, and Y. Javeed Maintaining residual chlorine levels in a water distribution networks is a challenging task; especially in the context of developing countries where water is usually supplied intermittently. To model chlorine decay in water distribution networks, it is very important to understand chlorine kinetics in bulk water. Recent studies suggested that chlorine decay rate depends on initial chlorine levels and type of organic and inorganic matter present in water, indicating that first order decay model is unable to accurately predict chlorine decay in bulk water. In this study, we employed two reactant model (2R) to estimate the fast and slow reacting components in surface water and groundwater. We carried out bench scale test for surface and groundwater at initial chlorine level of 1, 2 and 5 mg L −1 . We used decay datasets to estimate optimal parameter values for both surface water and groundwater. After calibration, the 2R model was validated with two decay dataset with varying initial chlorine concentration (ICC). This study came up with three important findings (a) the ratio of slow to fast reacting components in groundwater was thirty times greater than that of the surface water, (b) 2R model can accurately predict chlorine decay in surface water, 98 % of the variance in the chlorine decay test was explained by the model and (c) in case groundwater, 2R model prediction accuracy reduced with the decrease in ICC levels, only 87 % variance in data was explained by the model. This could be attributed to high slow to fast reactant ratio in groundwater.

Description: Application of Machine Learning For Real-time Evaluation of Salinity (or TDS) in Drinking Water Using Photonic Sensor Sandip Kumar Roy and Preeta Sharan Drink. Water Eng. Sci. Discuss., doi:10.5194/dwes-2016-4,2016 Manuscript under review for DWES (discussion: open, 0 comments) About 20 % of world population is living in the areas without sufficient portable water. 97 % of the water on the earth is sea water. Understanding the level of salinity/TDS of sea water is necessity. Currently determination of salt content is by chemical analysis and is time consuming. Our research is to develop a lab on chip optical sensor to measure percentage of salinity in water. Even a small % of salinity change in water can be detected in real time by the sensor continuously with accuracy.

Description: Application of Machine Learning For Real-time Evaluation of Salinity (or TDS) in Drinking Water Using Photonic Sensor Sandip Kumar Roy and Preeta Sharan Drink. Water Eng. Sci. Discuss., doi:10.5194/dwes-2016-4,2016 Manuscript under review for DWES (discussion: open, 0 comments) About 20 % of world population is living in the areas without sufficient portable water. 97 % of the water on the earth is sea water. Understanding the level of salinity/TDS of sea water is necessity. Currently determination of salt content is by chemical analysis and is time consuming. Our research is to develop a lab on chip optical sensor to measure percentage of salinity in water. Even a small % of salinity change in water can be detected in real time by the sensor continuously with accuracy.

Description: Investigation of the relationship between drinking water quality and landform classes using fuzzy AHP (case study: south of Firozabad, east of Fars province, Iran) Marzieh Mokarram and Dinesh Sathyamoorthy Drink. Water Eng. Sci. Discuss., doi:10.5194/dwes-2016-3,2016 Manuscript under review for DWES (discussion: open, 0 comments) In this study, fuzzy analytic hierarchy process (AHP) is used to study the relationship between drinking water quality and landform classes in south of Firozabad, east of Fars province, Iran. For determination of drinking water quality, parameters of calcium (Ca), chlorine (Cl), magnesium (Mg), thorium (TH), sodium (Na), electrical conductivity (EC), sulfate (So4) and total dissolved solids (TDS) were used. It was found that 8.29 % of the study area have low water quality; 64.01 %, moderate; 23.33 %, high; and very high, 4.38 %. Areas with suitable drinking water quality are located in parts of the southeast and southwest parts of the study area. The relationship between landform class and drinking water quality show that drinking water quality is high in the stream, valleys, upland drainages and local ridge classes, and low in the plain small and midslope classes.

Description: Investigation of the relationship between drinking water quality and landform classes using fuzzy AHP (case study: south of Firozabad, east of Fars province, Iran) Marzieh Mokarram and Dinesh Sathyamoorthy Drink. Water Eng. Sci. Discuss., doi:10.5194/dwes-2016-3,2016 Manuscript under review for DWES (discussion: open, 0 comments) In this study, fuzzy analytic hierarchy process (AHP) is used to study the relationship between drinking water quality and landform classes in south of Firozabad, east of Fars province, Iran. For determination of drinking water quality, parameters of calcium (Ca), chlorine (Cl), magnesium (Mg), thorium (TH), sodium (Na), electrical conductivity (EC), sulfate (So4) and total dissolved solids (TDS) were used. It was found that 8.29 % of the study area have low water quality; 64.01 %, moderate; 23.33 %, high; and very high, 4.38 %. Areas with suitable drinking water quality are located in parts of the southeast and southwest parts of the study area. The relationship between landform class and drinking water quality show that drinking water quality is high in the stream, valleys, upland drainages and local ridge classes, and low in the plain small and midslope classes.

Description: Optimized photodegradation of Bisphenol A in water using ZnO, TiO 2 and SnO 2 photocatalysts under UV radiation as a decontamination procedure Rudy Abo, Nicolai-Alexeji Kummer, and Broder J. Merkel Drink. Water Eng. Sci. Discuss., doi:10.5194/dwes-2016-5,2016 Manuscript under review for DWES (discussion: open, 0 comments) Contamination of water resources is continuously compounded as a result of rapid industrial development. Particularly, in heavily populated urban areas. This work proposes treatment way of water from endocrine disrupting resin Bisphenol A by means of photodegradation and oxidation techniques. The methodology developed after long time of lab experiments, and we believe that our results will support the future researches on water purification techniques from organic contamination products.

Description: Optimized photodegradation of Bisphenol A in water using ZnO, TiO 2 and SnO 2 photocatalysts under UV radiation as a decontamination procedure Rudy Abo, Nicolai-Alexeji Kummer, and Broder J. Merkel Drink. Water Eng. Sci. Discuss., doi:10.5194/dwes-2016-5,2016 Manuscript under review for DWES (discussion: open, 0 comments) Contamination of water resources is continuously compounded as a result of rapid industrial development. Particularly, in heavily populated urban areas. This work proposes treatment way of water from endocrine disrupting resin Bisphenol A by means of photodegradation and oxidation techniques. The methodology developed after long time of lab experiments, and we believe that our results will support the future researches on water purification techniques from organic contamination products.

Description: Optimized photodegradation of Bisphenol A in water using ZnO, TiO 2 and SnO 2 photocatalysts under UV radiation as a decontamination procedure Rudy Abo, Nicolai-Alexeji Kummer, and Broder J. Merkel Drink. Water Eng. Sci., 9, 27-35, doi:10.5194/dwes-9-27-2016, 2016 Contamination of water resources is continuously compounded as a result of rapid industrial development, particularly in heavily populated urban areas. This work proposes a water treatment method from endocrine disrupting resin Bisphenol A by means of photodegradation and oxidation techniques. The methodology was developed after many lab experiments, and we believe that our results will support future research on water purification techniques from organic contamination products.

Description: Optimized photodegradation of Bisphenol A in water using ZnO, TiO 2 and SnO 2 photocatalysts under UV radiation as a decontamination procedure Rudy Abo, Nicolai-Alexeji Kummer, and Broder J. Merkel Drink. Water Eng. Sci., 9, 27-35, doi:10.5194/dwes-9-27-2016, 2016 Contamination of water resources is continuously compounded as a result of rapid industrial development, particularly in heavily populated urban areas. This work proposes a water treatment method from endocrine disrupting resin Bisphenol A by means of photodegradation and oxidation techniques. The methodology was developed after many lab experiments, and we believe that our results will support future research on water purification techniques from organic contamination products.

Description: Application of optical tomography in the study of discolouration in drinking water distribution systems Drinking Water Engineering and Science Discussions, 4, 39-59, 2011 Author(s): P. van Thienen, R. Floris, and S. Meijering Theories describing the turbulent deposition of particles from aerosols have recently been applied to drinking water distribution. In order to allow the study of these processes in a quantitative way and internally observe a cloud of suspended particles in a pipe, we have developed an optical tomography technique and measuring device using low cost electronic components specifically for this application. The mathematical methodology and the electronic device are described in this paper, and tests of both the mathematical approach and the actual device are presented. We conclude that the described methodology may provide a valuable tool for the study of processes related to drinking water discolouration in the lab.

Description: Overcoming challenges in the classification of deep geothermal potential Geothermal Energy Science, 3, 19-39, 2015 Author(s): K. Breede, K. Dzebisashvili, and G. Falcone The geothermal community lacks a universal definition of deep geothermal systems. A minimum depth of 400 m is often assumed, with a further sub-classification into middle-deep geothermal systems for reservoirs found between 400 and 1000 m. Yet, the simplistic use of a depth cut-off is insufficient to uniquely determine the type of resource and its associated potential. Different definitions and criteria have been proposed in the past to frame deep geothermal systems. However, although they have valid assumptions, these frameworks lack systematic integration of correlated factors. To further complicate matters, new definitions such as hot dry rock (HDR), enhanced or engineered geothermal systems (EGSs) or deep heat mining have been introduced over the years. A clear and transparent approach is needed to estimate the potential of deep geothermal systems and be capable of distinguishing between resources of a different nature. In order to overcome the ambiguity associated with some past definitions such as EGS, this paper proposes the return to a more rigorous petrothermal versus hydrothermal classification. This would be superimposed with numerical criteria for the following: depth and temperature; predominance of conduction, convection or advection; formation type; rock properties; heat source type; requirement for formation stimulation and corresponding efficiency; requirement to provide the carrier fluid; well productivity (or injectivity); production (or circulation) flow rate; and heat recharge mode. Using the results from data mining of past and present deep geothermal projects worldwide, a classification of the same, according to the aforementioned criteria is proposed.

Description: Natural manganese deposits as catalyst for decomposing hydrogen peroxide Drinking Water Engineering and Science, 8, 3-8, 2015 Author(s): A. H. Knol, K. Lekkerkerker-Teunissen, and J. C. van Dijk Drinking water companies (are intending to) implement advanced oxidation processes (AOP) in their treatment schemes to increase the barrier against organic micropollutants (OMPs). It is necessary to decompose the excessive hydrogen peroxide after applying AOP to avoid negative effects in the following, often biological, treatment steps. A drinking water company in the western part of the Netherlands investigated decomposition of about 5.75 mg L −1 hydrogen peroxide in pre-treated Meuse river water with different catalysts on pilot scale. In down flow operation, the necessary reactor empty bed contact time (EBCT) with the commonly used granulated activated carbon (GAC) and waste ground water filter gravel (MCFgw) were found equal with 149 s, corresponding with a conversion rate constant r of 0.021 s −1 . The EBCT of the fine coating of ground water filter gravel (MC) was significantly shorter with a little more than 10 s ( r = 0.30 s −1 ). In up flow operation, with a flow rate of 20 m h −1 , the EBCT of coating MC increased till about 100 s ( r = 0.031 s −1 ), from which can be concluded, that the performance of this waste material is better compared with GAC, in both up and down flow operation. The necessary EBCT at average filtration rate of full scale dual layer filter material (MCFsw) amounted to 209 s ( r = 0.015 s −1 ). Regarding the average residence time in the full scale filters of 700 s, applying AOP in front of the filters could be an interesting alternative which makes a separate decomposition installation superfluous, on the condition that the primary functions of the filters are not affected.

Description: Reservoir characterization of the Upper Jurassic geothermal target formations (Molasse Basin, Germany): role of thermofacies as exploration tool Geothermal Energy Science, 3, 41-49, 2015 Author(s): S. Homuth, A. E. Götz, and I. Sass The Upper Jurassic carbonates of the southern German Molasse Basin are the target of numerous geothermal combined heat and power production projects since the year 2000. A production-orientated reservoir characterization is therefore of high economic interest. Outcrop analogue studies enable reservoir property prediction by determination and correlation of lithofacies-related thermo- and petrophysical parameters. A thermofacies classification of the carbonate formations serves to identify heterogeneities and production zones. The hydraulic conductivity is mainly controlled by tectonic structures and karstification, whilst the type and grade of karstification is facies related. The rock permeability has only a minor effect on the reservoir's sustainability. Physical parameters determined on oven-dried samples have to be corrected, applying reservoir transfer models to water-saturated reservoir conditions. To validate these calculated parameters, a Thermo-Triaxial-Cell simulating the temperature and pressure conditions of the reservoir is used and calorimetric and thermal conductivity measurements under elevated temperature conditions are performed. Additionally, core and cutting material from a 1600 m deep research drilling and a 4850 m (total vertical depth, measured depth: 6020 m) deep well is used to validate the reservoir property predictions. Under reservoir conditions a decrease in permeability of 2–3 magnitudes is observed due to the thermal expansion of the rock matrix. For tight carbonates the matrix permeability is temperature-controlled; the thermophysical matrix parameters are density-controlled. Density increases typically with depth and especially with higher dolomite content. Therefore, thermal conductivity increases; however the dominant factor temperature also decreases the thermal conductivity. Specific heat capacity typically increases with increasing depth and temperature. The lithofacies-related characterization and prediction of reservoir properties based on outcrop and drilling data demonstrates that this approach is a powerful tool for exploration and operation of geothermal reservoirs.

Description: Confirming anthropogenic influences on the major organic and inorganic constituents of rainwater in an urban area Drinking Water Engineering and Science Discussions, 8, 77-117, 2015 Author(s): K. Chon, Y. Kim, D. H. Bae, and J. Cho The chemical composition and organic compounds of rainwater were investigated from June to December 2012 at Gwangju in Korea. The volume weighted mean of pH ranged from 3.83 to 8.90 with an average of 5.78. 50 % of rainwater samples had pH values below 5.6. The volume-weighted mean concentration (VWMC) of major ions followed the order: Cl − 〉 SO 4 2− 〉 NH 4 + 〉 Na + 〉 NO 3 − 〉 Ca 2+ 〉 Mg 2+ 〉 K + . The VWMC of trace metals decreased in the order as follows Zn 〉 Al 〉 Fe 〉 Mn 〉 Pb 〉 Cu 〉 Ni 〉 Cd 〉 Cr. The VWMCs of major ions and trace metals were higher in winter than in summer. The high enrichment factors indicate that Zn, Pb, Cu, and Cd originated predominantly from anthropogenic sources. Factor analysis (principal component analysis) indicates the influence of anthropogenic pollutants, sea salt, and crustal materials on the chemical compositions of rainwater. Benzoic acids, 1H-Isoindole-1,3(2H)-dione, phthalic anhydride, benzene, acetic acids, 1,2-benzenedicarboxylic acids, benzonitrile, acetaldehyde, and acetamide were the most prominent pyrolysis fragments for rainwater organic compounds identified by pyrolysis gas chromatography/mass spectrometry (Py-GC/MS). The results indicate that anthropogenic sources are the most important factors affecting the organic composition of rainwater in urban area.

Description: Geothermal resources and reserves in Indonesia: an updated revision Geothermal Energy Science, 3, 1-6, 2015 Author(s): A. Fauzi More than 300 high- to low-enthalpy geothermal sources have been identified throughout Indonesia. From the early 1980s until the late 1990s, the geothermal potential for power production in Indonesia was estimated to be about 20 000 MWe. The most recent estimate exceeds 29 000 MWe derived from the 300 sites (Geological Agency, December 2013). This resource estimate has been obtained by adding all of the estimated geothermal potential resources and reserves classified as "speculative", "hypothetical", "possible", "probable", and "proven" from all sites where such information is available. However, this approach to estimating the geothermal potential is flawed because it includes double counting of some reserve estimates as resource estimates, thus giving an inflated figure for the total national geothermal potential. This paper describes an updated revision of the geothermal resource estimate in Indonesia using a more realistic methodology. The methodology proposes that the preliminary "Speculative Resource" category should cover the full potential of a geothermal area and form the base reference figure for the resource of the area. Further investigation of this resource may improve the level of confidence of the category of reserves but will not necessarily increase the figure of the "preliminary resource estimate" as a whole, unless the result of the investigation is higher. A previous paper (Fauzi, 2013a, b) redefined and revised the geothermal resource estimate for Indonesia. The methodology, adopted from Fauzi (2013a, b), will be fully described in this paper. As a result of using the revised methodology, the potential geothermal resources and reserves for Indonesia are estimated to be about 24 000 MWe, some 5000 MWe less than the 2013 national estimate.

Description: Natural manganese deposits as catalyst for decomposing hydrogen peroxide Drinking Water Engineering and Science Discussions, 8, 1-20, 2015 Author(s): A. H. Knol, K. Lekkerkerker-Teunissen, and J. C. van Dijk Drinking water companies more and more implement Advanced Oxidation Processes (AOP) in their treatment schemes to increase the barrier against organic micropollutants (OMPs). It is necessary to decompose the excessive hydrogen peroxide after applying AOP to avoid negative effects in the following, often biological, treatment steps. A drinking water company in the western part of the Netherlands investigated decomposition of about 5.75 mg L −1 hydrogen peroxide in pre-treated Meuse river water with different catalysts on pilot scale. In down flow operation, the necessary reactor Empty Bed Contact Time (EBCT) with the commonly used Granulated Activated Carbon (GAC) and waste ground water filter gravel (MCFgw) were the same with 149 s, corresponding with a conversion rate constant r of 0.021 s −1 . The EBCT of the fine coating of ground water filter gravel (MC) was significantly shorter with a little more than 10 s ( r = 0.30 s −1 ). In up flow operation, with a flow rate of 20 m h −1 , the EBCT of coating MC increased till about 100 s ( r = 0.031 s −1 ), from which can be concluded, that the performance of this waste material is better compared with GAC, in both up and down flow operation. The necessary EBCT at average filtration rate of full scale dual layer filter material (MCFsw) amounted to 209 s ( r = 0.015 s −1 ). Regarding the average residence time in the full scale filters of 700 s, applying AOP in front of the filters could be an interesting alternative which makes a separate decomposition installation superfluous, on the condition that the primary functions of the filters are not affected.

Description: Shower heat exchanger: reuse of energy from heated drinking water for CO 2 reduction Drinking Water Engineering and Science Discussions, 8, 119-141, 2015 Author(s): Z. Deng, S. Mol, and J. P. van der Hoek The heating of drinking water in households contributes for a significant amount to the emission of greenhouse gases. As a water utility aiming to operate climate neutral by 2020, Waternet needs to reduce its CO 2 emission by 53 kton yr −1 . To contribute to this ambition, a pilot project was carried out in Uilenstede, Amstelveen, the Netherlands, to recover the shower heat energy with a shower heat exchanger from Dutch Solar Systems. An experimental set up was built in the Waternet laboratory to compare field conditions and lab conditions. The energy recovery efficiency observed in the lab was 61–64 % under winter conditions and 58–62 % under summer conditions, while the energy recovery efficiency observed in Uilenstede was 57 % in December 2014. Based on the observations, 4 % of the total energy consumption of households in Amsterdam (electricity and gas) can be recovered with a shower heat exchanger installed in all households in Amsterdam, which also means a 54 kton yr −1 CO 2 emission reduction.

Description: Status of organochlorine pesticides in the drinking water well-field located in the Delhi region of the flood plains of river Yamuna Drinking Water Engineering and Science, 4, 51-60, 2011 Author(s): P. K. Mutiyar, A. K. Mittal, and A. Pekdeger This study presents the occurrence of pesticides in a well-field located in Yamuna flood plain of Delhi region. Ground water sampling campaigns were carried out during pre-monsoon and post-monsoon periods covering 21 borewells and 5 Ranney wells. Major 17 organochlorine pesticides (OCP's) along with other water quality parameters were monitored during this period. Pesticide concentrations were determined using GC-ECD, while GC-MS was used for confirmatory purposes. OCP's groups like ∑HCH, ∑DDT, endosulfan and aldrin were observed in this well-field. Concentration of OCPs from Ranney well exceeded the limit (1 μg l −1 ) prescribed by the Bureau of Indian Standards (BIS) in pre-monsoon season, though OCP levels in borewells were within BIS limits. However, these levels were very close to the World Health Organisation (WHO) and European Union (EU) limit of for pesticides (0.5 μg l −1 ) in many samples. Borewell produced better quality water compared to the water from Ranney wells. Although, the level of OCP's was slightly lower than prescribed limit of national regulatory agency but such low doses may cause long-term damage to human populations if such water is consumed for longer durations. At low doses OCP's acts as endocrine disrupting agent and cause metabolic disorders in local population.

Description: Application of optical tomography in the study of discolouration in drinking water distribution systems Drinking Water Engineering and Science, 4, 61-69, 2011 Author(s): P. van Thienen, R. Floris, and S. Meijering Theories describing the turbulent deposition of particles from aerosols have recently been applied to drinking water distribution. In order to allow the study of these processes in a quantitative way and internally observe a cloud of suspended particles in a pipe, we have developed an optical tomography technique and measuring device using low cost electronic components specifically for this application. The mathematical methodology and the electronic device are described in this paper, and tests of both the mathematical approach and the actual device are presented. We conclude that the mathematical framework presented is suitable and that the technical implementation works in a test setting. The described methodology may provide a valuable tool for the study of processes related to drinking water discolouration in the lab.

Description: A new model for the simplification of particle counting data Drinking Water Engineering and Science Discussions, 4, 151-172, 2011 Author(s): M. F. Fadal, J. Haarhoff, and S. Marais This paper proposes a three-parameter mathematical model to describe the particle size distribution in a water sample. The proposed model offers some conceptual advantages over two other models reported on previously, and also provides a better fit to the particle counting data obtained from 321 water samples taken over three years at a large South Africa water utility. By using the data from raw water samples taken from a moderately turbid, large surface impoundment, as well as samples from the same water after treatment, typical ranges of the model parameters are presented for both raw and treated water. Once calibrated, the model allows the calculation of total particle number and volumes over any randomly selected size interval of interest.

Description: Assessing variable speed pump efficiency in water distribution systems Drinking Water Engineering and Science Discussions, 5, 47-65, 2012 Author(s): A. Marchi, A. R. Simpson, and N. Ertugrul Energy savings and greenhouse gas emission reductions are increasingly becoming important design targets in many industrial systems where fossil fuel based electrical energy is heavily utilised. In water distribution systems (WDSs) a significant portion of operational cost is related to pumping. Recent studies have considered variable speed pumps (VSPs) which aim to vary the operating point of the pump to match demand to pumping rate. Depending on the system characteristics, this approach can lead to considerable savings in operational costs. In particular, cost reductions can take advantage of the demand variability and can decrease energy consumption significantly. One of the issues in using variable speed pumping systems, however, is the total efficiency of the electric motor/pump arrangement under a given operating condition. This paper aims to provide a comprehensive discussion about the components of WDS that incorporate variable speed pumps (including electric motors, inverters and the pumps themselves) to provide an insight of ways of increasing the system efficiency and hence to reduce energy consumption. In addition, specific attention is given to selection of motor types, sizing, duty cycle of pump (ratio of on-time and time period), losses due to installation and motor faults. All these factors affect the efficiency of motor drive/pump system.

Description: Fluoride in the drinking water of Pakistan and the possible risk of crippling fluorosis Drinking Water Engineering and Science, 6, 17-23, 2013 Author(s): M. A. Tahir and H. Rasheed To explore the possibility of fluoride toxicity, 747 water samples were collected from surface water and groundwater sources of 16 major cities of Pakistan, adopting a uniform sampling design with distribution of samples: Lahore (79), Kasur (46), Faisalabad (30), Khushab (50), Chakwal (51), Mianwali (30), Jhelum (53), Bahawalpur (60), Karachi (60), Mirpur Khas (55), Peshawar (38), Risalpur (35), Quetta (81), Ziarat (21), Loralai (21), and Mastung (37). Comparison of analytical findings with WHO Guidelines of Drinking Water for Fluoride (i.e., 1.5 ppm) has concluded that 16% of the monitored water sources have fluoride concentration beyond the permissible safe limit of 1.5 mg L −1 falling in the concentration range of 1.6–25 mg L −1 . The highest fluoride contamination (22%) is detected in the Balochistan province followed by 19% in Punjab province. Comparatively higher fluoride levels of 〉 20% in the groundwater sources like hand pumps supported the possibility of increased groundwater contamination as excessive fluoride concentrations are expected to come from calcium-poor aquifers and in areas where fluoride-bearing minerals are common or where cation exchange of sodium for calcium occurs. Field observations have also indicated the prevalence of fluoride-associated health implications in the study areas with excessive fluoride in water sources. Findings of this study have provided bidirectional vision for the epidemiological investigations as well as to mitigate the issues in the affected vicinities of fluoride-rich areas.

Description: Accumulation and modeling of particles in drinking water pipe fittings Drinking Water Engineering and Science Discussions, 5, 139-171, 2012 Author(s): K. Neilands, M. Bernats, and J. Rubulis The effect of pipe fittings – mainly T-pieces – on particle accumulation in drinking water distribution networks is shown in this work. The online measurements of flow and turbidity for cast iron, polyethylene and polyvinylchloride pipe sections have been linked with the analysis of pipe geometry. Up to 0.29 kg of the total mass of particles was found to be accumulated in T-pieces ranging from DN 100/100–DN 250/250. The accumulated amount of particles in the fittings was defined as J and introduced into the existing turbidity model PODDS (Prediction of Discolouration in Distribution Systems) proposed by Boxall et al. (2001), which describes the erosion of particles leading to discoloration events in drinking water networks, viz. sections, of straight pipes. It does not interpret the mobilization of particles in pipe fittings, however, which have been considered in this article. T-pieces were the object of this study and depending on the diameter or daily flow velocity, the coefficient J varied from 1.16 to 8.02.

Description: Dynamic hydraulic models to study sedimentation in drinking water networks in detail Drinking Water Engineering and Science Discussions, 5, 121-137, 2012 Author(s): I. W. M. Pothof and E. J. M. Blokker Sedimentation in drinking water networks can lead to discolouration complaints. A sufficient criterion to prevent sedimentation in drinking water networks is a daily maximum velocity of 0.25 m s −1 . Flushing experiments have shown that this criterion is a sufficient condition for a clean network, but not a necessary condition. Drinking water networks include many locations with a maximum velocity well below 0.25 m s −1 without sediment. Other criteria need to be developed to predict which locations are susceptible to sedimentation and to prevent sedimentation in future networks. More distinctive criteria are helpful to prioritise flushing operations and to prevent water quality complaints. The authors use three different numerical modelling approaches – quasi-steady, rigid column and water hammer – with a temporal discretisation of 1 s in order to assess the influence of unsteady flows on the wall shear stress, causing resuspension of sediment particles. The model predictions are combined with results from flushing experiments in the drinking water distribution system of Purmerend, the Netherlands. The waterhammer model does not result in essentially different flow distribution patterns, compared to the rigid column and quasi-steady modelling approach. The extra information from the waterhammer model is a velocity oscillation of approximately 0.02 m s −1 around the quasi-steady solution. The presence of stagnation zones and multiple flow direction reversals seem to be interesting new parameters to predict sediment accumulation, which are consistent with the observed turbidity data and theoretical considerations on critical shear stresses.

Description: Technical Note: Wet validation of optical tomography for drinking water discolouration studies Drinking Water Engineering and Science Discussions, 6, 27-38, 2013 Author(s): R. Floris, P. van Thienen, and H. Beverloo This paper presents a set of validation experiments for the reconstruction of a cross-sectional particle concentration field in a transparent pipe filled with a fluid using optical tomography.

Description: Numerical and experimental investigation of leaks in viscoelastic pressurized pipe flow Drinking Water Engineering and Science, 6, 11-16, 2013 Author(s): S. Meniconi, B. Brunone, M. Ferrante, and C. Massari This paper extends the analysis concerning the importance in numerical models of unsteady friction and viscoelasticity to transients in plastic pipes with an external flow due to a leak. In fact recently such a benchmarking analysis has been executed for the cases of a constant diameter pipe (Duan et al., 2010), a pipe with a partially closed in-line valve (Meniconi et al., 2012a), and a pipe with cross-section changes in series (Meniconi et al., 2012b). Tests are based on laboratory experiments carried out at the Water Engineering Laboratory (WEL) of the University of Perugia, Italy, and the use of different numerical models. The results show that it is crucial to take into account the viscoelasticity to simulate the main characteristics of the examined transients.

Description: Convective, intrusive geothermal plays: what about tectonics? Geothermal Energy Science, 3, 51-59, 2015 Author(s): A. Santilano, A. Manzella, G. Gianelli, A. Donato, G. Gola, I. Nardini, E. Trumpy, and S. Botteghi We revised the concept of convective, intrusive geothermal plays, considering that the tectonic setting is not, in our opinion, a discriminant parameter suitable for a classification. We analysed and compared four case studies: (i) Larderello (Italy), (ii) Mt Amiata (Italy), (iii) The Geysers (USA) and (iv) Kizildere (Turkey). The tectonic settings of these geothermal systems are different and a matter of debate, so it is hard to use this parameter, and the results of classification are ambiguous. We suggest a classification based on the age and nature of the heat source and the related hydrothermal circulation. Finally we propose to distinguish the convective geothermal plays as volcanic, young intrusive and amagmatic.

Description: Conversion of organic micropollutants with limited bromate formation during the Peroxone process in drinking water treatment Drinking Water Engineering and Science, 8, 25-34, 2015 Author(s): A. H. Knol, K. Lekkerkerker-Teunissen, C. J. Houtman, J. Scheideler, A. Ried, and J. C. van Dijk Advanced oxidation with O 3 / H 2 O 2 (peroxone) was conducted on pilot plant scale on pre-treated Meuse river water to investigate the conversion of organic micropollutants (OMPs) and the formation of bromate. Fourteen selected model compounds were dosed to the pre-treated river water on a regular basis to assess the efficiency of the peroxone process and to establish the influence of the water matrix. The ozone dose was the main factor in the conversion of the model compounds, however, the ozone dose was limited because of bromate formation. The hydrogen peroxide dosage had only a minor effect on the conversion, but it limited the bromate formation effectively. In terms of limited chemical consumption, maximal conversion and to comply the strict Dutch drinking water act for bromate of 1 μg L −1 , a practical peroxone setting was 6 mg L −1 hydrogen peroxide and 1.5 mg L −1 ozone. During the investigation period, the average conversion of the model compounds was 78.9 %. The conversion of OMPs was higher at higher water temperatures and lower concentrations of DOC and bicarbonate. The bromate formation also was higher at higher water temperature and lower bicarbonate concentration and proportional with the bromide concentration, above a threshold of about 32 μg L −1 bromide. The peroxone process can be controlled on basis of the (derived) parameters water temperature, bicarbonate and DOC.

Description: Clay-biodegradable polymer combination for pollutant removal from water Drinking Water Engineering and Science Discussions, 8, 177-196, 2015 Author(s): M. F. Mohd Amin, S. G. J. Heijman, and L. C. Rietveld In this study, a new treatment alternative is investigated to remove micropollutants from wastewater effectively and in a more cost-effective way. A potential solution is the use of clay in combination with biodegradable polymeric flocculants. Flocculation is viewed as the best method to get the optimum outcome from the combination of clay with starch. Clay is naturally abundantly available and relatively inexpensive compared to the conventional adsorbents used. Experimental studies were carried out with four different clays to select the best clay for further optimisation. The atrazine removal achieved is in the range of 10–99 % based on the clay concentration of 10–50 g L −1 . Optimisation of the best clay performer leads towards atrazine reduction of 〉 99 % with a dosage of 100 mg L −1 . The best and underperforming clays were then tested in other experiments with the addition of cationic starch flocculants. In this experiment, the addition of a polymer increased the atrazine removal for the underperforming clay to 46 % with only 10 mg L −1 clay dosages. The clay flocculation test was also performed to test the flocculation efficiency of clays by the polymer. Approximately 80–84 % of the clay is flocculated, which shows exceptional flocculation efficiency in removing both clays and atrazine from the water matrices.

Description: Corrosion control using hydroxide and bicarbonate alkalising agents in water drinking processes P. Torres-Lozada, K. A. Bueno-Zabala, L. G. Delgado-Cabrera, L. E. Barba-Ho, and C. H. Cruz-Vélez Drink. Water Eng. Sci. Discuss., 8, 53-76, doi:10.5194/dwesd-8-53-2015, 2015 Publication in DWES not foreseen (discussion: closed, 3 comments) The water supply industry is faced with three phenomena of great importance: the aggressiveness, corrosion, and incrustation of water distribution systems (WDS), which are primarily due to the low alkalinity of water sources and the addition of chemicals used in water treatment processes, which require pH adjustments during the last stage of the treatment process before going into the WDS. This article presents the results of using Ca(OH) 2 and NaOH with doses between 2 and 20 mg L −1 and NaHCO 3 and Na 2 CO 3 between 10 and 250 mg L −1 to adjust the pH of water treated from the Cauca River, which is located in Cali, Colombia, using stabilisation indices normally used in water treatment plants for pH monitoring processes and to better predict the behaviour of water in the WDS. The results indicate that for the case of the surface water source studied, which exhibits low alkalinity levels, the evaluated alkalising agents, with the exception of NaHCO 3 , can create conditions that lead to the precipitation of a~protective calcium carbonate film. Because the pH values that guarantee an adequate pH adjustment are higher (8.7–9.0) than those specified by the Colombian water code and because other international rules indicate that these values do not compromise the health of consumers, it is advisable to review and adjust the code in this respect.

Description: Preface: CCWI 2013 B. Brunone, M. Ferrante, S. Meniconi, and L. Berardi Drink. Water Eng. Sci., 7, 99-100, doi:10.5194/dwes-7-99-2014, 2014

Description: Corrigendum to "Preface: CCWI 2013" published in Drink. Water Eng. Sci., 7, 99–100, 2014 B. Brunone, M. Ferrante, S. Meniconi, and L. Berardi Drink. Water Eng. Sci., 8, 1-1, doi:10.5194/dwes-8-1-2015, 2015

Description: Conversion of organic micropollutants with limited bromate formation during the Peroxone process in drinking water treatment A. H. Knol, K. Lekkerkerker-Teunissen, C. J. Houtman, J. Scheideler, A. Ried, and J. C. van Dijk Drink. Water Eng. Sci., 8, 25-34, doi:10.5194/dwes-8-25-2015, 2015 Advanced oxidation with O 3 / H 2 O 2 (peroxone) was conducted on pilot plant scale on pre-treated Meuse river water to investigate the conversion of organic micropollutants (OMPs) and the formation of bromate. Fourteen selected model compounds were dosed to the pre-treated river water on a regular basis to assess the efficiency of the peroxone process and to establish the influence of the water matrix. The ozone dose was the main factor in the conversion of the model compounds, however, the ozone dose was limited because of bromate formation. The hydrogen peroxide dosage had only a minor effect on the conversion, but it limited the bromate formation effectively. In terms of limited chemical consumption, maximal conversion and to comply the strict Dutch drinking water act for bromate of 1 μg L −1 , a practical peroxone setting was 6 mg L −1 hydrogen peroxide and 1.5 mg L −1 ozone. During the investigation period, the average conversion of the model compounds was 78.9 %. The conversion of OMPs was higher at higher water temperatures and lower concentrations of DOC and bicarbonate. The bromate formation also was higher at higher water temperature and lower bicarbonate concentration and proportional with the bromide concentration, above a threshold of about 32 μg L −1 bromide. The peroxone process can be controlled on basis of the (derived) parameters water temperature, bicarbonate and DOC.

Description: Finite volume simulation of unsteady water pipe flow J. Fernández-Pato and P. García-Navarro Drink. Water Eng. Sci., 7, 83-92, doi:10.5194/dwes-7-83-2014, 2014 The most commonly used hydraulic network models used in the drinking water community exclusively consider fully filled pipes. However, water flow numerical simulation in urban pipe systems may require to model transitions between surface flow and pressurized flow in steady and transient situations. The governing equations for both flow types are different and this must be taken into account in order to get a complete numerical model for solving dynamically transients. In this work, a numerical simulation tool is developed, capable of simulating pipe networks mainly unpressurized, with isolated points of pressurization. For this purpose, the mathematical model is reformulated by means of the Preissmann slot method. This technique provides a reasonable estimation of the water pressure in cases of pressurization. The numerical model is based on the first order Roe's scheme, in the frame of finite volume methods. The novelty of the method is that it is adapted to abrupt transient situations, with subcritical and supercritical flows. The validation has been done by means of several cases with analytic solutions or empirical laboratory data. It has also been applied to some more complex and realistic cases, like junctions or pipe networks.

Description: Natural manganese deposits as catalyst for decomposing hydrogen peroxide A. H. Knol, K. Lekkerkerker-Teunissen, and J. C. van Dijk Drink. Water Eng. Sci., 8, 3-8, doi:10.5194/dwes-8-3-2015, 2015 Drinking water companies (are intending to) implement advanced oxidation processes (AOP) in their treatment schemes to increase the barrier against organic micropollutants (OMPs). It is necessary to decompose the excessive hydrogen peroxide after applying AOP to avoid negative effects in the following, often biological, treatment steps. A drinking water company in the western part of the Netherlands investigated decomposition of about 5.75 mg L −1 hydrogen peroxide in pre-treated Meuse river water with different catalysts on pilot scale. In down flow operation, the necessary reactor empty bed contact time (EBCT) with the commonly used granulated activated carbon (GAC) and waste ground water filter gravel (MCFgw) were found equal with 149 s, corresponding with a conversion rate constant r of 0.021 s −1 . The EBCT of the fine coating of ground water filter gravel (MC) was significantly shorter with a little more than 10 s ( r = 0.30 s −1 ). In up flow operation, with a flow rate of 20 m h −1 , the EBCT of coating MC increased till about 100 s ( r = 0.031 s −1 ), from which can be concluded, that the performance of this waste material is better compared with GAC, in both up and down flow operation. The necessary EBCT at average filtration rate of full scale dual layer filter material (MCFsw) amounted to 209 s ( r = 0.015 s −1 ). Regarding the average residence time in the full scale filters of 700 s, applying AOP in front of the filters could be an interesting alternative which makes a separate decomposition installation superfluous, on the condition that the primary functions of the filters are not affected.

Description: Household water treatment and safe storage – effectiveness and economics S. M. L. Stubbé, A. Pelgrim-Adams, G. L. Szanto, and D. van Halem Drink. Water Eng. Sci. Discuss., 8, 143-176, doi:10.5194/dwesd-8-143-2015, 2015 Manuscript under review for DWES (discussion: final response, 2 comments) Household Water Treatment and safe Storage (HWTS) systems aim to provide safe drinking water in an affordable manner. The effectiveness of these systems to remove pathogens is crucial for the health of its users. Different researches report wide ranges of effectiveness for each of the three selected systems: SODIS, ceramic and biosand filters. The resources available for the prices of HWTS also report wide ranges. In the data available no relation was observed between price and effectiveness.

Description: Conversion of organic micropollutants with limited bromate formation during the Peroxone process in drinking water treatment A. H. Knol, K. Lekkerkerker-Teunissen, C. J. Houtman, J. Scheideler, A. Ried, and J. C. van Dijk Drink. Water Eng. Sci., 8, 25-34, doi:10.5194/dwes-8-25-2015, 2015 Advanced oxidation with O 3 / H 2 O 2 (peroxone) was conducted on pilot plant scale on pre-treated Meuse river water to investigate the conversion of organic micropollutants (OMPs) and the formation of bromate. Fourteen selected model compounds were dosed to the pre-treated river water on a regular basis to assess the efficiency of the peroxone process and to establish the influence of the water matrix. The ozone dose was the main factor in the conversion of the model compounds, however, the ozone dose was limited because of bromate formation. The hydrogen peroxide dosage had only a minor effect on the conversion, but it limited the bromate formation effectively. In terms of limited chemical consumption, maximal conversion and to comply the strict Dutch drinking water act for bromate of 1 μg L −1 , a practical peroxone setting was 6 mg L −1 hydrogen peroxide and 1.5 mg L −1 ozone. During the investigation period, the average conversion of the model compounds was 78.9 %. The conversion of OMPs was higher at higher water temperatures and lower concentrations of DOC and bicarbonate. The bromate formation also was higher at higher water temperature and lower bicarbonate concentration and proportional with the bromide concentration, above a threshold of about 32 μg L −1 bromide. The peroxone process can be controlled on basis of the (derived) parameters water temperature, bicarbonate and DOC.

Description: Functioning conditions of the Casale pumping station in Mantova, Italy C. Capponi, M. Ferrante, M. Pedroni, B. Brunone, S. Meniconi, M. Zaghini, and F. Leoni Drink. Water Eng. Sci., 7, 93-97, doi:10.5194/dwes-7-93-2014, 2014 Pump speed, input power, pressure and discharge data are analyzed for evaluating functioning conditions of Casale pumping station in Mantova, Italy, managed by TeaAcque. A model based on the affinity laws is used to simulate the behavior of the installed variable speed pumps. Quadratic and cubic polynomial curves are used to fit the pump data given by the affinity laws. Such curves allow predicting the efficiency when the functioning conditions change. The relationship between the rotation speed and the efficiency is also derived.

Description: Shower heat exchanger: reuse of energy from heated drinking water for CO 2 reduction Z. Deng, S. Mol, and J. P. van der Hoek Drink. Water Eng. Sci. Discuss., 8, 119-141, doi:10.5194/dwesd-8-119-2015, 2015 Revised manuscript accepted for DWES (discussion: closed, 3 comments) The heating of drinking water in households contributes for a significant amount to the emission of greenhouse gases. As a water utility aiming to operate climate neutral by 2020, Waternet needs to reduce its CO 2 emission by 53 kton yr −1 . To contribute to this ambition, a pilot project was carried out in Uilenstede, Amstelveen, the Netherlands, to recover the shower heat energy with a shower heat exchanger from Dutch Solar Systems. An experimental set up was built in the Waternet laboratory to compare field conditions and lab conditions. The energy recovery efficiency observed in the lab was 61–64 % under winter conditions and 58–62 % under summer conditions, while the energy recovery efficiency observed in Uilenstede was 57 % in December 2014. Based on the observations, 4 % of the total energy consumption of households in Amsterdam (electricity and gas) can be recovered with a shower heat exchanger installed in all households in Amsterdam, which also means a 54 kton yr −1 CO 2 emission reduction.

Description: Natural manganese deposits as catalyst for decomposing hydrogen peroxide A. H. Knol, K. Lekkerkerker-Teunissen, and J. C. van Dijk Drink. Water Eng. Sci., 8, 3-8, doi:10.5194/dwes-8-3-2015, 2015 Drinking water companies (are intending to) implement advanced oxidation processes (AOP) in their treatment schemes to increase the barrier against organic micropollutants (OMPs). It is necessary to decompose the excessive hydrogen peroxide after applying AOP to avoid negative effects in the following, often biological, treatment steps. A drinking water company in the western part of the Netherlands investigated decomposition of about 5.75 mg L −1 hydrogen peroxide in pre-treated Meuse river water with different catalysts on pilot scale. In down flow operation, the necessary reactor empty bed contact time (EBCT) with the commonly used granulated activated carbon (GAC) and waste ground water filter gravel (MCFgw) were found equal with 149 s, corresponding with a conversion rate constant r of 0.021 s −1 . The EBCT of the fine coating of ground water filter gravel (MC) was significantly shorter with a little more than 10 s ( r = 0.30 s −1 ). In up flow operation, with a flow rate of 20 m h −1 , the EBCT of coating MC increased till about 100 s ( r = 0.031 s −1 ), from which can be concluded, that the performance of this waste material is better compared with GAC, in both up and down flow operation. The necessary EBCT at average filtration rate of full scale dual layer filter material (MCFsw) amounted to 209 s ( r = 0.015 s −1 ). Regarding the average residence time in the full scale filters of 700 s, applying AOP in front of the filters could be an interesting alternative which makes a separate decomposition installation superfluous, on the condition that the primary functions of the filters are not affected.

Description: Optimization of coagulation-flocculation parameters using a photometric dispersion analyser S. R. Ramphal and M. S. Sibiya Drink. Water Eng. Sci., 7, 73-82, doi:10.5194/dwes-7-73-2014, 2014 The size and structural characteristics of floc particles are important design and control parameters in water treatment and should be rapidly monitored with a reasonable amount of accuracy. In this study, a photometric dispersion analyser (PDA) coupled to standard jar test experiments was used to optimize coagulation-flocculation parameters while monitoring floc size and structure as well as the rate of floc formation during coagulation using alum. The optimal coagulation conditions were as follows: sample pH 8; alum dosage, 3 mg L −1 as Al 3+ ; G value, 172 s −1 ; rapid mixing time, 20 s. These conditions resulted in unstable treated water having a calcium carbonate precipitation potential (CCPP) of −15 mg L −1 as CaCO 3 and required a slaked lime dosage of 17 mg L −1 as CaCO 3 to equilibrate CCPP to acceptable levels. PDA data revealed that aggregation rate and steady-state variance are primary parameters as both have substantial influence on coagulation-flocculation efficiency. However, the average steady state ratio, although an important parameter, had a lessened impact on coagulation-flocculation efficiency. The results of this study showed that the PDA instrument is an important tool in coagulation kinetic studies and can be employed as an additional tool in the optimization of coagulation conditions.

Description: Immobilized photocatalyst on stainless steel woven meshes assuring efficient light distribution in a solar reactor A. S. El-Kalliny, S. F. Ahmed, L. C. Rietveld, and P. W. Appel Drink. Water Eng. Sci., 7, 41-52, doi:10.5194/dwes-7-41-2014, 2014 An immobilized TiO 2 photocatalyst with a high specific surface area was prepared on stainless steel woven meshes in order to be used packed in layers for water purification. Immobilization of such a complex shape needs a special coating technique. For this purpose, dip coating and electrophoretic deposition (EPD) techniques were used. The EPD technique gave the TiO 2 coating films a better homogeneity and adhesion, fewer cracks, and a higher · OH formation than the dip coating technique. The woven mesh structure packed in layers guaranteed an efficient light-penetration in water treatment reactor. A simple equation model was used to describe the distribution of light through the mesh layers in the presence of absorbing medium (e.g., colored water with humic acids). Maximum three or four coated meshes were enough to harvest the solar UV light from 300 nm to 400 nm with a high penetration efficiency. The separation distance between the mesh layers played an important role in the efficiency of solar light penetration through the coated mesh layers, especially in case of colored water contaminated with high concentrations of humic acid.

Description: Corrigendum to "Preface: CCWI 2013" published in Drink. Water Eng. Sci., 7, 99–100, 2014 B. Brunone, M. Ferrante, S. Meniconi, and L. Berardi Drink. Water Eng. Sci., 8, 1-1, doi:10.5194/dwes-8-1-2015, 2015

Description: WaterMet 2 : a tool for integrated analysis of sustainability-based performance of urban water systems K. Behzadian, Z. Kapelan, G. Venkatesh, H. Brattebø, and S. Sægrov Drink. Water Eng. Sci., 7, 63-72, doi:10.5194/dwes-7-63-2014, 2014 This paper presents the "WaterMet 2 " model for long-term assessment of urban water system (UWS) performance which will be used for strategic planning of the integrated UWS. WaterMet 2 quantifies the principal water-related flows and other metabolism-based fluxes in the UWS such as materials, chemicals, energy and greenhouse gas emissions. The suggested model is demonstrated through sustainability-based assessment of an integrated real-life UWS for a daily time-step over a 30-year planning horizon. The integrated UWS modelled by WaterMet 2 includes both water supply and wastewater systems. Given a rapid population growth, WaterMet 2 calculates six quantitative sustainability-based indicators of the UWS. The result of the water supply reliability (94%) shows the need for appropriate intervention options over the planning horizon. Five intervention strategies are analysed in WaterMet 2 and their quantified performance is compared with respect to the criteria. Multi-criteria decision analysis is then used to rank the intervention strategies based on different weights from the involved stakeholders' perspectives. The results demonstrate that the best and robust strategies are those which improve the performance of both water supply and wastewater systems.

Description: Corrosion control using hydroxide and bicarbonate alkalising agents in water drinking processes P. Torres-Lozada, K. A. Bueno-Zabala, L. G. Delgado-Cabrera, L. E. Barba-Ho, and C. H. Cruz-Vélez Drink. Water Eng. Sci. Discuss., 8, 53-76, doi:10.5194/dwesd-8-53-2015, 2015 Publication in DWES not foreseen (discussion: closed, 3 comments) The water supply industry is faced with three phenomena of great importance: the aggressiveness, corrosion, and incrustation of water distribution systems (WDS), which are primarily due to the low alkalinity of water sources and the addition of chemicals used in water treatment processes, which require pH adjustments during the last stage of the treatment process before going into the WDS. This article presents the results of using Ca(OH) 2 and NaOH with doses between 2 and 20 mg L −1 and NaHCO 3 and Na 2 CO 3 between 10 and 250 mg L −1 to adjust the pH of water treated from the Cauca River, which is located in Cali, Colombia, using stabilisation indices normally used in water treatment plants for pH monitoring processes and to better predict the behaviour of water in the WDS. The results indicate that for the case of the surface water source studied, which exhibits low alkalinity levels, the evaluated alkalising agents, with the exception of NaHCO 3 , can create conditions that lead to the precipitation of a~protective calcium carbonate film. Because the pH values that guarantee an adequate pH adjustment are higher (8.7–9.0) than those specified by the Colombian water code and because other international rules indicate that these values do not compromise the health of consumers, it is advisable to review and adjust the code in this respect.

Description: Pump schedules optimisation with pressure aspects in complex large-scale water distribution systems P. Skworcow, D. Paluszczyszyn, and B. Ulanicki Drink. Water Eng. Sci., 7, 53-62, doi:10.5194/dwes-7-53-2014, 2014 This paper considers optimisation of pump and valve schedules in complex large-scale water distribution networks (WDN), taking into account pressure aspects such as minimum service pressure and pressure-dependent leakage. An optimisation model is automatically generated in the GAMS language from a hydraulic model in the EPANET format and from additional files describing operational constraints, electricity tariffs and pump station configurations. The paper describes in details how each hydraulic component is modelled. To reduce the size of the optimisation problem the full hydraulic model is simplified using module reduction algorithm, while retaining the nonlinear characteristics of the model. Subsequently, a nonlinear programming solver CONOPT is used to solve the optimisation model, which is in the form of Nonlinear Programming with Discontinuous Derivatives (DNLP). The results produced by CONOPT are processed further by heuristic algorithms to generate integer solution. The proposed approached was tested on a large-scale WDN model provided in the EPANET format. The considered WDN included complex structures and interactions between pump stations. Solving of several scenarios considering different horizons, time steps, operational constraints, demand levels and topological changes demonstrated ability of the approach to automatically generate and solve optimisation problems for a variety of requirements.

Description: Functioning conditions of the Casale pumping station in Mantova, Italy C. Capponi, M. Ferrante, M. Pedroni, B. Brunone, S. Meniconi, M. Zaghini, and F. Leoni Drink. Water Eng. Sci., 7, 93-97, doi:10.5194/dwes-7-93-2014, 2014 Pump speed, input power, pressure and discharge data are analyzed for evaluating functioning conditions of Casale pumping station in Mantova, Italy, managed by TeaAcque. A model based on the affinity laws is used to simulate the behavior of the installed variable speed pumps. Quadratic and cubic polynomial curves are used to fit the pump data given by the affinity laws. Such curves allow predicting the efficiency when the functioning conditions change. The relationship between the rotation speed and the efficiency is also derived.

Description: Conversion of organic micropollutants with limited bromate formation during the Peroxone process in drinking water treatment A. H. Knol, K. Lekkerkerker-Teunissen, C. J. Houtman, J. Scheideler, A. Ried, and J. C. van Dijk Drink. Water Eng. Sci., 8, 25-34, doi:10.5194/dwes-8-25-2015, 2015 Advanced oxidation with O 3 / H 2 O 2 (peroxone) was conducted on pilot plant scale on pre-treated Meuse river water to investigate the conversion of organic micropollutants (OMPs) and the formation of bromate. Fourteen selected model compounds were dosed to the pre-treated river water on a regular basis to assess the efficiency of the peroxone process and to establish the influence of the water matrix. The ozone dose was the main factor in the conversion of the model compounds, however, the ozone dose was limited because of bromate formation. The hydrogen peroxide dosage had only a minor effect on the conversion, but it limited the bromate formation effectively. In terms of limited chemical consumption, maximal conversion and to comply the strict Dutch drinking water act for bromate of 1 μg L −1 , a practical peroxone setting was 6 mg L −1 hydrogen peroxide and 1.5 mg L −1 ozone. During the investigation period, the average conversion of the model compounds was 78.9 %. The conversion of OMPs was higher at higher water temperatures and lower concentrations of DOC and bicarbonate. The bromate formation also was higher at higher water temperature and lower bicarbonate concentration and proportional with the bromide concentration, above a threshold of about 32 μg L −1 bromide. The peroxone process can be controlled on basis of the (derived) parameters water temperature, bicarbonate and DOC.

Description: Pump schedules optimisation with pressure aspects in complex large-scale water distribution systems P. Skworcow, D. Paluszczyszyn, and B. Ulanicki Drink. Water Eng. Sci., 7, 53-62, doi:10.5194/dwes-7-53-2014, 2014 This paper considers optimisation of pump and valve schedules in complex large-scale water distribution networks (WDN), taking into account pressure aspects such as minimum service pressure and pressure-dependent leakage. An optimisation model is automatically generated in the GAMS language from a hydraulic model in the EPANET format and from additional files describing operational constraints, electricity tariffs and pump station configurations. The paper describes in details how each hydraulic component is modelled. To reduce the size of the optimisation problem the full hydraulic model is simplified using module reduction algorithm, while retaining the nonlinear characteristics of the model. Subsequently, a nonlinear programming solver CONOPT is used to solve the optimisation model, which is in the form of Nonlinear Programming with Discontinuous Derivatives (DNLP). The results produced by CONOPT are processed further by heuristic algorithms to generate integer solution. The proposed approached was tested on a large-scale WDN model provided in the EPANET format. The considered WDN included complex structures and interactions between pump stations. Solving of several scenarios considering different horizons, time steps, operational constraints, demand levels and topological changes demonstrated ability of the approach to automatically generate and solve optimisation problems for a variety of requirements.

Description: Natural manganese deposits as catalyst for decomposing hydrogen peroxide A. H. Knol, K. Lekkerkerker-Teunissen, and J. C. van Dijk Drink. Water Eng. Sci., 8, 3-8, doi:10.5194/dwes-8-3-2015, 2015 Drinking water companies (are intending to) implement advanced oxidation processes (AOP) in their treatment schemes to increase the barrier against organic micropollutants (OMPs). It is necessary to decompose the excessive hydrogen peroxide after applying AOP to avoid negative effects in the following, often biological, treatment steps. A drinking water company in the western part of the Netherlands investigated decomposition of about 5.75 mg L −1 hydrogen peroxide in pre-treated Meuse river water with different catalysts on pilot scale. In down flow operation, the necessary reactor empty bed contact time (EBCT) with the commonly used granulated activated carbon (GAC) and waste ground water filter gravel (MCFgw) were found equal with 149 s, corresponding with a conversion rate constant r of 0.021 s −1 . The EBCT of the fine coating of ground water filter gravel (MC) was significantly shorter with a little more than 10 s ( r = 0.30 s −1 ). In up flow operation, with a flow rate of 20 m h −1 , the EBCT of coating MC increased till about 100 s ( r = 0.031 s −1 ), from which can be concluded, that the performance of this waste material is better compared with GAC, in both up and down flow operation. The necessary EBCT at average filtration rate of full scale dual layer filter material (MCFsw) amounted to 209 s ( r = 0.015 s −1 ). Regarding the average residence time in the full scale filters of 700 s, applying AOP in front of the filters could be an interesting alternative which makes a separate decomposition installation superfluous, on the condition that the primary functions of the filters are not affected.

Description: Immobilized photocatalyst on stainless steel woven meshes assuring efficient light distribution in a solar reactor A. S. El-Kalliny, S. F. Ahmed, L. C. Rietveld, and P. W. Appel Drink. Water Eng. Sci., 7, 41-52, doi:10.5194/dwes-7-41-2014, 2014 An immobilized TiO 2 photocatalyst with a high specific surface area was prepared on stainless steel woven meshes in order to be used packed in layers for water purification. Immobilization of such a complex shape needs a special coating technique. For this purpose, dip coating and electrophoretic deposition (EPD) techniques were used. The EPD technique gave the TiO 2 coating films a better homogeneity and adhesion, fewer cracks, and a higher · OH formation than the dip coating technique. The woven mesh structure packed in layers guaranteed an efficient light-penetration in water treatment reactor. A simple equation model was used to describe the distribution of light through the mesh layers in the presence of absorbing medium (e.g., colored water with humic acids). Maximum three or four coated meshes were enough to harvest the solar UV light from 300 nm to 400 nm with a high penetration efficiency. The separation distance between the mesh layers played an important role in the efficiency of solar light penetration through the coated mesh layers, especially in case of colored water contaminated with high concentrations of humic acid.

Description: Confirming anthropogenic influences on the major organic and inorganic constituents of rainwater in an urban area K. Chon, Y. Kim, D. H. Bae, and J. Cho Drink. Water Eng. Sci., 8, 35-48, doi:10.5194/dwes-8-35-2015, 2015 Recently, rainwater composition affected by atmospheric pollutants has been the topic of intense study in East Asia because of its adverse environmental and human health effects. In the present study, the chemical composition and organic compounds of rainwater were investigated from June to December 2012 at Gwangju in Korea. The aim of this study is to determine the seasonal variation of rainwater chemical composition and to identify possible sources of inorganic and organic compounds. The volume-weighted mean of pH ranged from 3.83 to 8.90 with an average of 5.78. Of rainwater samples, 50 % had pH values below 5.6. The volume-weighted mean concentration (VWMC) of major ions followed the order Cl − 〉 SO 4 2− 〉 NH 4 + 〉 Na + 〉 NO 3 − 〉 Ca 2+ 〉 Mg 2+ 〉 K + . The VWMC of trace metals decreased in the order Zn 〉 Al 〉 Fe 〉 Mn 〉 Pb 〉 Cu 〉 Ni 〉 Cd 〉 Cr. The VWMCs of major ions and trace metals were higher in winter than in summer. The high enrichment factors indicate that Zn, Pb, Cu, and Cd originated predominantly from anthropogenic sources. Factor analysis (principal component analysis) indicates the influence of anthropogenic pollutants, sea salt, and crustal materials on the chemical compositions of rainwater. Benzoic acids, 1H-isoindole-1,3(2H)-dione, phthalic anhydride, benzene, acetic acids, 1,2-benzenedicarboxylic acids, benzonitrile, acetaldehyde, and acetamide were the most prominent pyrolysis fragments for rainwater organic compounds identified by pyrolysis gas chromatography/mass spectrometry (Py-GC/MS). The results indicate that anthropogenic sources are the most important factors affecting the organic composition of rainwater in an urban area.

Description: Estimating fast and slow reacting component in surface and groundwater using 2R model P. Jamwal, M. N. Naveen, and Y. Javeed Drink. Water Eng. Sci. Discuss., 8, 197-217, doi:10.5194/dwesd-8-197-2015, 2015 Manuscript under review for DWES (discussion: final response, 4 comments) Maintaining residual chlorine levels in a water distribution networks is a challenging task; especially in the context of developing countries where water is usually supplied intermittently. To model chlorine decay in water distribution networks, it is very important to understand chlorine kinetics in bulk water. Recent studies suggested that chlorine decay rate depends on initial chlorine levels and type of organic and inorganic matter present in water, indicating that first order decay model is unable to accurately predict chlorine decay in bulk water. In this study, we employed two reactant model (2R) to estimate the fast and slow reacting components in surface water and groundwater. We carried out bench scale test for surface and groundwater at initial chlorine level of 1, 2 and 5 mg L −1 . We used decay datasets to estimate optimal parameter values for both surface water and groundwater. After calibration, the 2R model was validated with two decay dataset with varying initial chlorine concentration (ICC). This study came up with three important findings (a) the ratio of slow to fast reacting components in groundwater was thirty times greater than that of the surface water, (b) 2R model can accurately predict chlorine decay in surface water, 98 % of the variance in the chlorine decay test was explained by the model and (c) in case groundwater, 2R model prediction accuracy reduced with the decrease in ICC levels, only 87 % variance in data was explained by the model. This could be attributed to high slow to fast reactant ratio in groundwater.

Description: Clay-biodegradable polymer combination for pollutant removal from water M. F. Mohd Amin, S. G. J. Heijman, and L. C. Rietveld Drink. Water Eng. Sci. Discuss., 8, 177-196, doi:10.5194/dwesd-8-177-2015, 2015 Manuscript under review for DWES (discussion: open, 0 comments) In this study, the use of clay in combination with biodegradable polymeric flocculants is investigated to remove micropollutants from wastewater effectively. Experimental studies were carried out with four different clays to select the best clay for further optimisation. The removal achieved is in the range of 10-99% based on the clay concentration of 10 mg/L-50 g/L. The clay flocculation efficiency test leads towards 80-84% of the clay being flocculated by the polymer from the water matrixes.

Description: Water Expert : a conceptualized framework for development of a rule-based decision support system for distribution system decontamination J. L. Gutenson, A. N. S. Ernest, J. R. Fattic, L. E. Ormsbee, A. A. Oubeidillah, and X. Zhang Drink. Water Eng. Sci., 8, 9-24, doi:10.5194/dwes-8-9-2015, 2015 Significant drinking water contamination events pose a serious threat to public and environmental health. This paper examines the development of Water Expert, a software tool for assisting decision makers in response and recovery following a contamination event. The decision making process undertaken during contamination events in evaluated. Results indicate that the decision making process is limited without technological intervention.

Description: Optimization of coagulation-flocculation parameters using a photometric dispersion analyser S. R. Ramphal and M. S. Sibiya Drink. Water Eng. Sci., 7, 73-82, doi:10.5194/dwes-7-73-2014, 2014 The size and structural characteristics of floc particles are important design and control parameters in water treatment and should be rapidly monitored with a reasonable amount of accuracy. In this study, a photometric dispersion analyser (PDA) coupled to standard jar test experiments was used to optimize coagulation-flocculation parameters while monitoring floc size and structure as well as the rate of floc formation during coagulation using alum. The optimal coagulation conditions were as follows: sample pH 8; alum dosage, 3 mg L −1 as Al 3+ ; G value, 172 s −1 ; rapid mixing time, 20 s. These conditions resulted in unstable treated water having a calcium carbonate precipitation potential (CCPP) of −15 mg L −1 as CaCO 3 and required a slaked lime dosage of 17 mg L −1 as CaCO 3 to equilibrate CCPP to acceptable levels. PDA data revealed that aggregation rate and steady-state variance are primary parameters as both have substantial influence on coagulation-flocculation efficiency. However, the average steady state ratio, although an important parameter, had a lessened impact on coagulation-flocculation efficiency. The results of this study showed that the PDA instrument is an important tool in coagulation kinetic studies and can be employed as an additional tool in the optimization of coagulation conditions.

Description: Household water treatment and safe storage – effectiveness and economics S. M. L. Stubbé, A. Pelgrim-Adams, G. L. Szanto, and D. van Halem Drink. Water Eng. Sci. Discuss., 8, 143-176, doi:10.5194/dwesd-8-143-2015, 2015 Manuscript under review for DWES (discussion: final response, 2 comments) Household Water Treatment and safe Storage (HWTS) systems aim to provide safe drinking water in an affordable manner. The effectiveness of these systems to remove pathogens is crucial for the health of its users. Different researches report wide ranges of effectiveness for each of the three selected systems: SODIS, ceramic and biosand filters. The resources available for the prices of HWTS also report wide ranges. In the data available no relation was observed between price and effectiveness.

Description: Pump schedules optimisation with pressure aspects in complex large-scale water distribution systems P. Skworcow, D. Paluszczyszyn, and B. Ulanicki Drink. Water Eng. Sci., 7, 53-62, doi:10.5194/dwes-7-53-2014, 2014 This paper considers optimisation of pump and valve schedules in complex large-scale water distribution networks (WDN), taking into account pressure aspects such as minimum service pressure and pressure-dependent leakage. An optimisation model is automatically generated in the GAMS language from a hydraulic model in the EPANET format and from additional files describing operational constraints, electricity tariffs and pump station configurations. The paper describes in details how each hydraulic component is modelled. To reduce the size of the optimisation problem the full hydraulic model is simplified using module reduction algorithm, while retaining the nonlinear characteristics of the model. Subsequently, a nonlinear programming solver CONOPT is used to solve the optimisation model, which is in the form of Nonlinear Programming with Discontinuous Derivatives (DNLP). The results produced by CONOPT are processed further by heuristic algorithms to generate integer solution. The proposed approached was tested on a large-scale WDN model provided in the EPANET format. The considered WDN included complex structures and interactions between pump stations. Solving of several scenarios considering different horizons, time steps, operational constraints, demand levels and topological changes demonstrated ability of the approach to automatically generate and solve optimisation problems for a variety of requirements.

Description: WaterMet 2 : a tool for integrated analysis of sustainability-based performance of urban water systems K. Behzadian, Z. Kapelan, G. Venkatesh, H. Brattebø, and S. Sægrov Drink. Water Eng. Sci., 7, 63-72, doi:10.5194/dwes-7-63-2014, 2014 This paper presents the "WaterMet 2 " model for long-term assessment of urban water system (UWS) performance which will be used for strategic planning of the integrated UWS. WaterMet 2 quantifies the principal water-related flows and other metabolism-based fluxes in the UWS such as materials, chemicals, energy and greenhouse gas emissions. The suggested model is demonstrated through sustainability-based assessment of an integrated real-life UWS for a daily time-step over a 30-year planning horizon. The integrated UWS modelled by WaterMet 2 includes both water supply and wastewater systems. Given a rapid population growth, WaterMet 2 calculates six quantitative sustainability-based indicators of the UWS. The result of the water supply reliability (94%) shows the need for appropriate intervention options over the planning horizon. Five intervention strategies are analysed in WaterMet 2 and their quantified performance is compared with respect to the criteria. Multi-criteria decision analysis is then used to rank the intervention strategies based on different weights from the involved stakeholders' perspectives. The results demonstrate that the best and robust strategies are those which improve the performance of both water supply and wastewater systems.

Description: Functioning conditions of the Casale pumping station in Mantova, Italy C. Capponi, M. Ferrante, M. Pedroni, B. Brunone, S. Meniconi, M. Zaghini, and F. Leoni Drink. Water Eng. Sci., 7, 93-97, doi:10.5194/dwes-7-93-2014, 2014 Pump speed, input power, pressure and discharge data are analyzed for evaluating functioning conditions of Casale pumping station in Mantova, Italy, managed by TeaAcque. A model based on the affinity laws is used to simulate the behavior of the installed variable speed pumps. Quadratic and cubic polynomial curves are used to fit the pump data given by the affinity laws. Such curves allow predicting the efficiency when the functioning conditions change. The relationship between the rotation speed and the efficiency is also derived.

Description: Confirming anthropogenic influences on the major organic and inorganic constituents of rainwater in an urban area K. Chon, Y. Kim, D. H. Bae, and J. Cho Drink. Water Eng. Sci., 8, 35-48, doi:10.5194/dwes-8-35-2015, 2015 Recently, rainwater composition affected by atmospheric pollutants has been the topic of intense study in East Asia because of its adverse environmental and human health effects. In the present study, the chemical composition and organic compounds of rainwater were investigated from June to December 2012 at Gwangju in Korea. The aim of this study is to determine the seasonal variation of rainwater chemical composition and to identify possible sources of inorganic and organic compounds. The volume-weighted mean of pH ranged from 3.83 to 8.90 with an average of 5.78. Of rainwater samples, 50 % had pH values below 5.6. The volume-weighted mean concentration (VWMC) of major ions followed the order Cl − 〉 SO 4 2− 〉 NH 4 + 〉 Na + 〉 NO 3 − 〉 Ca 2+ 〉 Mg 2+ 〉 K + . The VWMC of trace metals decreased in the order Zn 〉 Al 〉 Fe 〉 Mn 〉 Pb 〉 Cu 〉 Ni 〉 Cd 〉 Cr. The VWMCs of major ions and trace metals were higher in winter than in summer. The high enrichment factors indicate that Zn, Pb, Cu, and Cd originated predominantly from anthropogenic sources. Factor analysis (principal component analysis) indicates the influence of anthropogenic pollutants, sea salt, and crustal materials on the chemical compositions of rainwater. Benzoic acids, 1H-isoindole-1,3(2H)-dione, phthalic anhydride, benzene, acetic acids, 1,2-benzenedicarboxylic acids, benzonitrile, acetaldehyde, and acetamide were the most prominent pyrolysis fragments for rainwater organic compounds identified by pyrolysis gas chromatography/mass spectrometry (Py-GC/MS). The results indicate that anthropogenic sources are the most important factors affecting the organic composition of rainwater in an urban area.

Description: Shower heat exchanger: reuse of energy from heated drinking water for CO 2 reduction Z. Deng, S. Mol, and J. P. van der Hoek Drink. Water Eng. Sci. Discuss., 8, 119-141, doi:10.5194/dwesd-8-119-2015, 2015 Revised manuscript accepted for DWES (discussion: closed, 3 comments) The heating of drinking water in households contributes for a significant amount to the emission of greenhouse gases. As a water utility aiming to operate climate neutral by 2020, Waternet needs to reduce its CO 2 emission by 53 kton yr −1 . To contribute to this ambition, a pilot project was carried out in Uilenstede, Amstelveen, the Netherlands, to recover the shower heat energy with a shower heat exchanger from Dutch Solar Systems. An experimental set up was built in the Waternet laboratory to compare field conditions and lab conditions. The energy recovery efficiency observed in the lab was 61–64 % under winter conditions and 58–62 % under summer conditions, while the energy recovery efficiency observed in Uilenstede was 57 % in December 2014. Based on the observations, 4 % of the total energy consumption of households in Amsterdam (electricity and gas) can be recovered with a shower heat exchanger installed in all households in Amsterdam, which also means a 54 kton yr −1 CO 2 emission reduction.

Description: Estimating fast and slow reacting component in surface and groundwater using 2R model P. Jamwal, M. N. Naveen, and Y. Javeed Drink. Water Eng. Sci. Discuss., 8, 197-217, doi:10.5194/dwesd-8-197-2015, 2015 Manuscript under review for DWES (discussion: final response, 4 comments) Maintaining residual chlorine levels in a water distribution networks is a challenging task; especially in the context of developing countries where water is usually supplied intermittently. To model chlorine decay in water distribution networks, it is very important to understand chlorine kinetics in bulk water. Recent studies suggested that chlorine decay rate depends on initial chlorine levels and type of organic and inorganic matter present in water, indicating that first order decay model is unable to accurately predict chlorine decay in bulk water. In this study, we employed two reactant model (2R) to estimate the fast and slow reacting components in surface water and groundwater. We carried out bench scale test for surface and groundwater at initial chlorine level of 1, 2 and 5 mg L −1 . We used decay datasets to estimate optimal parameter values for both surface water and groundwater. After calibration, the 2R model was validated with two decay dataset with varying initial chlorine concentration (ICC). This study came up with three important findings (a) the ratio of slow to fast reacting components in groundwater was thirty times greater than that of the surface water, (b) 2R model can accurately predict chlorine decay in surface water, 98 % of the variance in the chlorine decay test was explained by the model and (c) in case groundwater, 2R model prediction accuracy reduced with the decrease in ICC levels, only 87 % variance in data was explained by the model. This could be attributed to high slow to fast reactant ratio in groundwater.

Description: Clay-biodegradable polymer combination for pollutant removal from water M. F. Mohd Amin, S. G. J. Heijman, and L. C. Rietveld Drink. Water Eng. Sci. Discuss., 8, 177-196, doi:10.5194/dwesd-8-177-2015, 2015 Manuscript under review for DWES (discussion: open, 0 comments) In this study, the use of clay in combination with biodegradable polymeric flocculants is investigated to remove micropollutants from wastewater effectively. Experimental studies were carried out with four different clays to select the best clay for further optimisation. The removal achieved is in the range of 10-99% based on the clay concentration of 10 mg/L-50 g/L. The clay flocculation efficiency test leads towards 80-84% of the clay being flocculated by the polymer from the water matrixes.

Description: Immobilized photocatalyst on stainless steel woven meshes assuring efficient light distribution in a solar reactor A. S. El-Kalliny, S. F. Ahmed, L. C. Rietveld, and P. W. Appel Drink. Water Eng. Sci., 7, 41-52, doi:10.5194/dwes-7-41-2014, 2014 An immobilized TiO 2 photocatalyst with a high specific surface area was prepared on stainless steel woven meshes in order to be used packed in layers for water purification. Immobilization of such a complex shape needs a special coating technique. For this purpose, dip coating and electrophoretic deposition (EPD) techniques were used. The EPD technique gave the TiO 2 coating films a better homogeneity and adhesion, fewer cracks, and a higher · OH formation than the dip coating technique. The woven mesh structure packed in layers guaranteed an efficient light-penetration in water treatment reactor. A simple equation model was used to describe the distribution of light through the mesh layers in the presence of absorbing medium (e.g., colored water with humic acids). Maximum three or four coated meshes were enough to harvest the solar UV light from 300 nm to 400 nm with a high penetration efficiency. The separation distance between the mesh layers played an important role in the efficiency of solar light penetration through the coated mesh layers, especially in case of colored water contaminated with high concentrations of humic acid.

Description: Water Expert : a conceptualized framework for development of a rule-based decision support system for distribution system decontamination J. L. Gutenson, A. N. S. Ernest, J. R. Fattic, L. E. Ormsbee, A. A. Oubeidillah, and X. Zhang Drink. Water Eng. Sci., 8, 9-24, doi:10.5194/dwes-8-9-2015, 2015 Significant drinking water contamination events pose a serious threat to public and environmental health. This paper examines the development of Water Expert, a software tool for assisting decision makers in response and recovery following a contamination event. The decision making process undertaken during contamination events in evaluated. Results indicate that the decision making process is limited without technological intervention.

Description: Preface: CCWI 2013 B. Brunone, M. Ferrante, S. Meniconi, and L. Berardi Drink. Water Eng. Sci., 7, 99-100, doi:10.5194/dwes-7-99-2014, 2014

Description: Finite volume simulation of unsteady water pipe flow J. Fernández-Pato and P. García-Navarro Drink. Water Eng. Sci., 7, 83-92, doi:10.5194/dwes-7-83-2014, 2014 The most commonly used hydraulic network models used in the drinking water community exclusively consider fully filled pipes. However, water flow numerical simulation in urban pipe systems may require to model transitions between surface flow and pressurized flow in steady and transient situations. The governing equations for both flow types are different and this must be taken into account in order to get a complete numerical model for solving dynamically transients. In this work, a numerical simulation tool is developed, capable of simulating pipe networks mainly unpressurized, with isolated points of pressurization. For this purpose, the mathematical model is reformulated by means of the Preissmann slot method. This technique provides a reasonable estimation of the water pressure in cases of pressurization. The numerical model is based on the first order Roe's scheme, in the frame of finite volume methods. The novelty of the method is that it is adapted to abrupt transient situations, with subcritical and supercritical flows. The validation has been done by means of several cases with analytic solutions or empirical laboratory data. It has also been applied to some more complex and realistic cases, like junctions or pipe networks.

Description: Confirming anthropogenic influences on the major organic and inorganic constituents of rainwater in an urban area K. Chon, Y. Kim, D. H. Bae, and J. Cho Drink. Water Eng. Sci., 8, 35-48, doi:10.5194/dwes-8-35-2015, 2015 Recently, rainwater composition affected by atmospheric pollutants has been the topic of intense study in East Asia because of its adverse environmental and human health effects. In the present study, the chemical composition and organic compounds of rainwater were investigated from June to December 2012 at Gwangju in Korea. The aim of this study is to determine the seasonal variation of rainwater chemical composition and to identify possible sources of inorganic and organic compounds. The volume-weighted mean of pH ranged from 3.83 to 8.90 with an average of 5.78. Of rainwater samples, 50 % had pH values below 5.6. The volume-weighted mean concentration (VWMC) of major ions followed the order Cl − 〉 SO 4 2− 〉 NH 4 + 〉 Na + 〉 NO 3 − 〉 Ca 2+ 〉 Mg 2+ 〉 K + . The VWMC of trace metals decreased in the order Zn 〉 Al 〉 Fe 〉 Mn 〉 Pb 〉 Cu 〉 Ni 〉 Cd 〉 Cr. The VWMCs of major ions and trace metals were higher in winter than in summer. The high enrichment factors indicate that Zn, Pb, Cu, and Cd originated predominantly from anthropogenic sources. Factor analysis (principal component analysis) indicates the influence of anthropogenic pollutants, sea salt, and crustal materials on the chemical compositions of rainwater. Benzoic acids, 1H-isoindole-1,3(2H)-dione, phthalic anhydride, benzene, acetic acids, 1,2-benzenedicarboxylic acids, benzonitrile, acetaldehyde, and acetamide were the most prominent pyrolysis fragments for rainwater organic compounds identified by pyrolysis gas chromatography/mass spectrometry (Py-GC/MS). The results indicate that anthropogenic sources are the most important factors affecting the organic composition of rainwater in an urban area.

Description: Water Expert : a conceptualized framework for development of a rule-based decision support system for distribution system decontamination J. L. Gutenson, A. N. S. Ernest, J. R. Fattic, L. E. Ormsbee, A. A. Oubeidillah, and X. Zhang Drink. Water Eng. Sci., 8, 9-24, doi:10.5194/dwes-8-9-2015, 2015 Significant drinking water contamination events pose a serious threat to public and environmental health. This paper examines the development of Water Expert, a software tool for assisting decision makers in response and recovery following a contamination event. The decision making process undertaken during contamination events in evaluated. Results indicate that the decision making process is limited without technological intervention.

Description: WaterMet 2 : a tool for integrated analysis of sustainability-based performance of urban water systems K. Behzadian, Z. Kapelan, G. Venkatesh, H. Brattebø, and S. Sægrov Drink. Water Eng. Sci., 7, 63-72, doi:10.5194/dwes-7-63-2014, 2014 This paper presents the "WaterMet 2 " model for long-term assessment of urban water system (UWS) performance which will be used for strategic planning of the integrated UWS. WaterMet 2 quantifies the principal water-related flows and other metabolism-based fluxes in the UWS such as materials, chemicals, energy and greenhouse gas emissions. The suggested model is demonstrated through sustainability-based assessment of an integrated real-life UWS for a daily time-step over a 30-year planning horizon. The integrated UWS modelled by WaterMet 2 includes both water supply and wastewater systems. Given a rapid population growth, WaterMet 2 calculates six quantitative sustainability-based indicators of the UWS. The result of the water supply reliability (94%) shows the need for appropriate intervention options over the planning horizon. Five intervention strategies are analysed in WaterMet 2 and their quantified performance is compared with respect to the criteria. Multi-criteria decision analysis is then used to rank the intervention strategies based on different weights from the involved stakeholders' perspectives. The results demonstrate that the best and robust strategies are those which improve the performance of both water supply and wastewater systems.

Description: Confirming anthropogenic influences on the major organic and inorganic constituents of rainwater in an urban area Drinking Water Engineering and Science, 8, 35-48, 2015 Author(s): K. Chon, Y. Kim, D. H. Bae, and J. Cho Recently, rainwater composition affected by atmospheric pollutants has been the topic of intense study in East Asia because of its adverse environmental and human health effects. In the present study, the chemical composition and organic compounds of rainwater were investigated from June to December 2012 at Gwangju in Korea. The aim of this study is to determine the seasonal variation of rainwater chemical composition and to identify possible sources of inorganic and organic compounds. The volume-weighted mean of pH ranged from 3.83 to 8.90 with an average of 5.78. Of rainwater samples, 50 % had pH values below 5.6. The volume-weighted mean concentration (VWMC) of major ions followed the order Cl − 〉 SO 4 2− 〉 NH 4 + 〉 Na + 〉 NO 3 − 〉 Ca 2+ 〉 Mg 2+ 〉 K + . The VWMC of trace metals decreased in the order Zn 〉 Al 〉 Fe 〉 Mn 〉 Pb 〉 Cu 〉 Ni 〉 Cd 〉 Cr. The VWMCs of major ions and trace metals were higher in winter than in summer. The high enrichment factors indicate that Zn, Pb, Cu, and Cd originated predominantly from anthropogenic sources. Factor analysis (principal component analysis) indicates the influence of anthropogenic pollutants, sea salt, and crustal materials on the chemical compositions of rainwater. Benzoic acids, 1H-isoindole-1,3(2H)-dione, phthalic anhydride, benzene, acetic acids, 1,2-benzenedicarboxylic acids, benzonitrile, acetaldehyde, and acetamide were the most prominent pyrolysis fragments for rainwater organic compounds identified by pyrolysis gas chromatography/mass spectrometry (Py-GC/MS). The results indicate that anthropogenic sources are the most important factors affecting the organic composition of rainwater in an urban area.

Description: Optimization of coagulation-flocculation parameters using a photometric dispersion analyser S. R. Ramphal and M. S. Sibiya Drink. Water Eng. Sci., 7, 73-82, doi:10.5194/dwes-7-73-2014, 2014 The size and structural characteristics of floc particles are important design and control parameters in water treatment and should be rapidly monitored with a reasonable amount of accuracy. In this study, a photometric dispersion analyser (PDA) coupled to standard jar test experiments was used to optimize coagulation-flocculation parameters while monitoring floc size and structure as well as the rate of floc formation during coagulation using alum. The optimal coagulation conditions were as follows: sample pH 8; alum dosage, 3 mg L −1 as Al 3+ ; G value, 172 s −1 ; rapid mixing time, 20 s. These conditions resulted in unstable treated water having a calcium carbonate precipitation potential (CCPP) of −15 mg L −1 as CaCO 3 and required a slaked lime dosage of 17 mg L −1 as CaCO 3 to equilibrate CCPP to acceptable levels. PDA data revealed that aggregation rate and steady-state variance are primary parameters as both have substantial influence on coagulation-flocculation efficiency. However, the average steady state ratio, although an important parameter, had a lessened impact on coagulation-flocculation efficiency. The results of this study showed that the PDA instrument is an important tool in coagulation kinetic studies and can be employed as an additional tool in the optimization of coagulation conditions.

Description: Finite volume simulation of unsteady water pipe flow J. Fernández-Pato and P. García-Navarro Drink. Water Eng. Sci., 7, 83-92, doi:10.5194/dwes-7-83-2014, 2014 The most commonly used hydraulic network models used in the drinking water community exclusively consider fully filled pipes. However, water flow numerical simulation in urban pipe systems may require to model transitions between surface flow and pressurized flow in steady and transient situations. The governing equations for both flow types are different and this must be taken into account in order to get a complete numerical model for solving dynamically transients. In this work, a numerical simulation tool is developed, capable of simulating pipe networks mainly unpressurized, with isolated points of pressurization. For this purpose, the mathematical model is reformulated by means of the Preissmann slot method. This technique provides a reasonable estimation of the water pressure in cases of pressurization. The numerical model is based on the first order Roe's scheme, in the frame of finite volume methods. The novelty of the method is that it is adapted to abrupt transient situations, with subcritical and supercritical flows. The validation has been done by means of several cases with analytic solutions or empirical laboratory data. It has also been applied to some more complex and realistic cases, like junctions or pipe networks.

Description: Geothermal heat pump system assisted by geothermal hot spring M. Nakagawa and Y. Koizumi Geoth. Energ. Sci., 4, 1-10, doi:10.5194/gtes-4-1-2016, 2016 Abandoned mines are usually nothing but problems. The author attempts to show that it is feasible to turn this local problem into an economic benefit by combining other locally available resources such as geothermal heat.

Description: Effectiveness of acidizing geothermal wells in the South German Molasse Basin S. Schumacher and R. Schulz Geoth. Energ. Sci., 1, 1-11, doi:10.5194/gtes-1-1-2013, 2013 In Germany, many hydro-geothermal plants have been constructed in recent years, primarily in the region of Munich. As the host formation here mainly consists of carbonates, nearly all recently drilled wells have been acidized in order to improve the well yield. In this study, the effectiveness of these acid treatments is analyzed with respect to the amount of acid used and the number of acid treatments carried out per well. The results show that the first acid treatment has the largest effect, while subsequent acidizing improves the well only marginally. Data also indicate that continued acidizing can lead to degradation of the well. These findings may not only be important for geothermal installations in Germany but also for projects, for example, in Austria, France or China where geothermal energy is produced from carbonate formations as well.

Description: Geothermometric evaluation of geothermal resources in southeastern Idaho G. Neupane, E. D. Mattson, T. L. McLing, C. D. Palmer, R. W. Smith, T. R. Wood, and R. K. Podgorney Geoth. Energ. Sci., 4, 11-22, doi:10.5194/gtes-4-11-2016, 2016 Geothermal potential of southern part of Idaho in the US was recognized in the early 1970s; however, the commercial utilization of geothermal resources in the area is yet to be realized. The composition of hot spring/well water can tell us how hot the water at depth is. In this study, we assembled several existing thermal water compositions to estimate reservoir temperatures with a new tool. Our results show that some areas (e.g., Preston) in southern Idaho have good geothermal potential.

Description: Shower heat exchanger: reuse of energy from heated drinking water for CO 2 reduction Z. Deng, S. Mol, and J. P. van der Hoek Drink. Water Eng. Sci., 9, 1-8, doi:10.5194/dwes-9-1-2016, 2016 During a shower, a shower heat exchanger from Dutch Solar System can recover more than half of the thermal energy from the heated drinking water. Under a positive condition, installing shower heat exchangers might lead to a reduction of 54 kton CO 2 per year in Amsterdam. The research proves the efficiency and potential of the shower heat exchanger, by carrying out experiments in the laboratory and collecting data from the Uilenstede project site, a student housing estate near Amsterdam.

Description: Shower heat exchanger: reuse of energy from heated drinking water for CO 2 reduction Z. Deng, S. Mol, and J. P. van der Hoek Drink. Water Eng. Sci., 9, 1-8, doi:10.5194/dwes-9-1-2016, 2016 During a shower, a shower heat exchanger from Dutch Solar System can recover more than half of the thermal energy from the heated drinking water. Under a positive condition, installing shower heat exchangers might lead to a reduction of 54 kton CO 2 per year in Amsterdam. The research proves the efficiency and potential of the shower heat exchanger, by carrying out experiments in the laboratory and collecting data from the Uilenstede project site, a student housing estate near Amsterdam.

Description: Geochemical study on hot-spring water in West New Britain Province, Papua New Guinea M. M. Lahan, R. T. Verave, and P. Y. Irarue Geoth. Energ. Sci., 3, 61-67, doi:10.5194/gtes-3-61-2015, 2015 West New Britain Province, which occupies the western part of New Britain Island in Papua New Guinea, is ideally located within an active tectonic region that influences volcanism creating an environment favourable for geothermal activity. Geothermal mapping of surface manifestations reveals high temperature geothermal prospects along the northern coastline of West New Britain Province that are further confirmed by geochemical analysis. The occurrence of geothermal features is confined to the Quaternary Kimbe Volcanics and alluvium in the lowland areas. The features in Talasea appear to be controlled by deep-seated northerly trending faults while structures in Hoskins also appear to be deep seated but have not been identified. The geothermal systems in West New Britain Province have not been drilled, but preliminary reconnaissance geothermal mapping and geochemical analysis reveals four high temperature geothermal prospects suitable for further investigation and development of geothermal energy. These are the Pangalu (Rabili) and Talasea Station geothermal prospects in Talasea and Kasiloli (Magouru) and Silanga (Bakama and Sakalu) geothermal prospects in Hoskins. The calculated reservoir temperatures for these fields are in the range of 245–310 °C. Recommendations are made for further follow-up exploratory investigations.

Description: Classification of geothermal resources by potential L. Rybach Geoth. Energ. Sci., 3, 13-17, doi:10.5194/gtes-3-13-2015, 2015 A new resource classification scheme is described, based on different geothermal potentials: theoretical, technical, economic, sustainable, developable – decreasing successively in size. In converting theoretical to technical potential, the recovery factor (the ratio extractable heat/heat present at depth) is of key importance. The proposed classification of potentials provides a useful template for standardizing the future reporting of geothermal energy resources worldwide.

Description: Overcoming challenges in the classification of deep geothermal potential K. Breede, K. Dzebisashvili, and G. Falcone Geoth. Energ. Sci., 3, 19-39, doi:10.5194/gtes-3-19-2015, 2015 The geothermal community lacks a universal definition of deep geothermal systems. A minimum depth of 400 m is often assumed, with a further sub-classification into middle-deep geothermal systems for reservoirs found between 400 and 1000 m. Yet, the simplistic use of a depth cut-off is insufficient to uniquely determine the type of resource and its associated potential. Different definitions and criteria have been proposed in the past to frame deep geothermal systems. However, although they have valid assumptions, these frameworks lack systematic integration of correlated factors. To further complicate matters, new definitions such as hot dry rock (HDR), enhanced or engineered geothermal systems (EGSs) or deep heat mining have been introduced over the years. A clear and transparent approach is needed to estimate the potential of deep geothermal systems and be capable of distinguishing between resources of a different nature. In order to overcome the ambiguity associated with some past definitions such as EGS, this paper proposes the return to a more rigorous petrothermal versus hydrothermal classification. This would be superimposed with numerical criteria for the following: depth and temperature; predominance of conduction, convection or advection; formation type; rock properties; heat source type; requirement for formation stimulation and corresponding efficiency; requirement to provide the carrier fluid; well productivity (or injectivity); production (or circulation) flow rate; and heat recharge mode. Using the results from data mining of past and present deep geothermal projects worldwide, a classification of the same, according to the aforementioned criteria is proposed.

Description: Assessing the prospective resource base for enhanced geothermal systems in Europe J. Limberger, P. Calcagno, A. Manzella, E. Trumpy, T. Boxem, M. P. D. Pluymaekers, and J.-D. van Wees Geoth. Energ. Sci., 2, 55-71, doi:10.5194/gtes-2-55-2014, 2014 In this study the resource base for EGS (enhanced geothermal systems) in Europe was quantified and economically constrained, applying a discounted cash-flow model to different techno-economic scenarios for future EGS in 2020, 2030, and 2050. Temperature is a critical parameter that controls the amount of thermal energy available in the subsurface. Therefore, the first step in assessing the European resource base for EGS is the construction of a subsurface temperature model of onshore Europe. Subsurface temperatures were computed to a depth of 10 km below ground level for a regular 3-D hexahedral grid with a horizontal resolution of 10 km and a vertical resolution of 250 m. Vertical conductive heat transport was considered as the main heat transfer mechanism. Surface temperature and basal heat flow were used as boundary conditions for the top and bottom of the model, respectively. If publicly available, the most recent and comprehensive regional temperature models, based on data from wells, were incorporated. With the modeled subsurface temperatures and future technical and economic scenarios, the technical potential and minimum levelized cost of energy (LCOE) were calculated for each grid cell of the temperature model. Calculations for a typical EGS scenario yield costs of EUR 215 MWh −1 in 2020, EUR 127 MWh −1 in 2030, and EUR 70 MWh −1 in 2050. Cutoff values of EUR 200 MWh −1 in 2020, EUR 150 MWh −1 in 2030, and EUR 100 MWh −1 in 2050 are imposed to the calculated LCOE values in each grid cell to limit the technical potential, resulting in an economic potential for Europe of 19 GW e in 2020, 22 GW e in 2030, and 522 GW e in 2050. The results of our approach do not only provide an indication of prospective areas for future EGS in Europe, but also show a more realistic cost determined and depth-dependent distribution of the technical potential by applying different well cost models for 2020, 2030, and 2050.

Description: Reservoir characterization of the Upper Jurassic geothermal target formations (Molasse Basin, Germany): role of thermofacies as exploration tool S. Homuth, A. E. Götz, and I. Sass Geoth. Energ. Sci., 3, 41-49, doi:10.5194/gtes-3-41-2015, 2015 The Upper Jurassic carbonates of the southern German Molasse Basin are the target of numerous geothermal combined heat and power production projects since the year 2000. A production-orientated reservoir characterization is therefore of high economic interest. Outcrop analogue studies enable reservoir property prediction by determination and correlation of lithofacies-related thermo- and petrophysical parameters. A thermofacies classification of the carbonate formations serves to identify heterogeneities and production zones. The hydraulic conductivity is mainly controlled by tectonic structures and karstification, whilst the type and grade of karstification is facies related. The rock permeability has only a minor effect on the reservoir's sustainability. Physical parameters determined on oven-dried samples have to be corrected, applying reservoir transfer models to water-saturated reservoir conditions. To validate these calculated parameters, a Thermo-Triaxial-Cell simulating the temperature and pressure conditions of the reservoir is used and calorimetric and thermal conductivity measurements under elevated temperature conditions are performed. Additionally, core and cutting material from a 1600 m deep research drilling and a 4850 m (total vertical depth, measured depth: 6020 m) deep well is used to validate the reservoir property predictions. Under reservoir conditions a decrease in permeability of 2–3 magnitudes is observed due to the thermal expansion of the rock matrix. For tight carbonates the matrix permeability is temperature-controlled; the thermophysical matrix parameters are density-controlled. Density increases typically with depth and especially with higher dolomite content. Therefore, thermal conductivity increases; however the dominant factor temperature also decreases the thermal conductivity. Specific heat capacity typically increases with increasing depth and temperature. The lithofacies-related characterization and prediction of reservoir properties based on outcrop and drilling data demonstrates that this approach is a powerful tool for exploration and operation of geothermal reservoirs.

Description: Effectiveness of acidizing geothermal wells in the South German Molasse Basin S. Schumacher and R. Schulz Geoth. Energ. Sci., 1, 1-11, doi:10.5194/gtes-1-1-2013, 2013 In Germany, many hydro-geothermal plants have been constructed in recent years, primarily in the region of Munich. As the host formation here mainly consists of carbonates, nearly all recently drilled wells have been acidized in order to improve the well yield. In this study, the effectiveness of these acid treatments is analyzed with respect to the amount of acid used and the number of acid treatments carried out per well. The results show that the first acid treatment has the largest effect, while subsequent acidizing improves the well only marginally. Data also indicate that continued acidizing can lead to degradation of the well. These findings may not only be important for geothermal installations in Germany but also for projects, for example, in Austria, France or China where geothermal energy is produced from carbonate formations as well.

Description: Corrosion control using hydroxide and bicarbonate alkalising agents in water drinking processes P. Torres-Lozada, K. A. Bueno-Zabala, L. G. Delgado-Cabrera, L. E. Barba-Ho, and C. H. Cruz-Vélez Drink. Water Eng. Sci. Discuss., 8, 53-76, doi:10.5194/dwesd-8-53-2015, 2015 Publication in DWES not foreseen (discussion: closed, 3 comments) The water supply industry is faced with three phenomena of great importance: the aggressiveness, corrosion, and incrustation of water distribution systems (WDS), which are primarily due to the low alkalinity of water sources and the addition of chemicals used in water treatment processes, which require pH adjustments during the last stage of the treatment process before going into the WDS. This article presents the results of using Ca(OH) 2 and NaOH with doses between 2 and 20 mg L −1 and NaHCO 3 and Na 2 CO 3 between 10 and 250 mg L −1 to adjust the pH of water treated from the Cauca River, which is located in Cali, Colombia, using stabilisation indices normally used in water treatment plants for pH monitoring processes and to better predict the behaviour of water in the WDS. The results indicate that for the case of the surface water source studied, which exhibits low alkalinity levels, the evaluated alkalising agents, with the exception of NaHCO 3 , can create conditions that lead to the precipitation of a~protective calcium carbonate film. Because the pH values that guarantee an adequate pH adjustment are higher (8.7–9.0) than those specified by the Colombian water code and because other international rules indicate that these values do not compromise the health of consumers, it is advisable to review and adjust the code in this respect.