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  • Keywords: vitamins; activated sludge; industrial wastewater; porous pots; Amtox™  (1)
  • Sinkholes  (1)
  • Springer  (2)
  • 2000-2004  (2)
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  • Springer  (2)
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  • 2000-2004  (2)
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  • 1
    ISSN: 1432-0495
    Keywords: Key words Karst terranes ; Electrical resistivity tomography ; Sinkholes ; Pinnacles and cutters
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Notes: Abstract  Sinkhole collapse is one of the main limitations on the development of karst areas, especially where bedrock is covered by unconsolidated material. Studies of sinkhole formation have shown that sinkholes are likely to develop in cutter (enlarged joint) zones as a result of subterranean erosion by flowing groundwater. Because of the irregular distribution of pinnacles and cutters on the bedrock surface, uncertainties arise when "hit-or-miss" borehole drilling is used to locate potential collapse sites. A high-resolution geophysical technique capable of depicting the details of the bedrock surface is essential for guiding the drilling program. Dipole-dipole electrical resistivity tomography (ERT) was used to map the bedrock surface at a site in southern Indiana where limestone is covered by about 9 m of clayey soils. Forty-nine transects were conducted over an area of approximately 42,037 m2. The electrode spacing was 3 m. The length of the transects varied from 81 to 249 m. The tomographs were interpreted with the aid of soil borings. The repeatability of ERT was evaluated by comparing the rock surface elevations interpreted from pairs of transects where they crossed each other. The average difference was 2.4 m, with a maximum of 10 m. The discrepancy between interpreted bedrock-surface elevations for a transect intersection may be caused by variations in the subsurface geology normal to the transect. Averaging the elevation data interpreted from different transects improved the ERT results. A bedrock surface map was generated using only the averaged elevation data at the transect junctions. The accuracy of the map was further evaluated using data from four exploratory boreholes. The average difference between interpreted and actual bedrock surface-elevations was less than 0.4 m. The map shows two large troughs in the limestone surface: one coinciding with an existing sinkhole basin, while the other is in alignment with a small topographic valley. Because sinkholes were observed at the same elevation interval in similar valleys in the vicinity, the delineated trough may have implications for future land use at the site.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Journal of industrial microbiology and biotechnology 24 (2000), S. 267-274 
    ISSN: 1476-5535
    Keywords: Keywords: vitamins; activated sludge; industrial wastewater; porous pots; Amtox™
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The process performance and metabolic rates of samples of activated sludge dosed with vitamin supplements have been compared. After initial screening, four vitamins and two metals as single supplements and in pairs, were dosed continuously into the mixed liquor of an activated sludge simulation. Toxicity, oxygen demand removal, respiration rates and suspended solids were measured to monitor the effect on process efficiency. It was confirmed experimentally that an industrial wastewater stream did not contain a sufficient supply of micronutrients for efficient biological treatment. This was concluded from the observation that control sludge batches (receiving no supplements) averaged chemical oxygen demand removal efficiency of 58%. Dosing micronutrients into the mixed liquor produced removal efficiencies of up to 69%. Some of the supplements increased the respiration rate of the sludge while some decreased it, indicating a range of stimulatory and inhibitory effects. Complex interactions between micronutrients that were dosed simultaneously were evident. Several positive effects led to the conclusion that micronutrients have the potential to optimise process performance of activated sludge plants treating industrial wastewater. The addition of phosphorus/niacin and molybdenum/lactoflavin removed wastewater components that were toxic to nitrifiers as indicated through toxicity testing, thus protecting downstream nitrification/denitrification treatment processes. Journal of Industrial Microbiology & Biotechnology (2000) 24, 267–274.
    Type of Medium: Electronic Resource
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