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Lee, B. H. (2006). Constructed wetlands: Treatment of concentrated storm water runoff (Part A). Environmental Engineering Science, 23(2), 320–331.
Abstract: The aim of this research was to assess the treatment efficiencies for gully pot liquor of experimental vertical-flow constructed wetland filters containing Phragmites australis (Cav.) Trin. ex Steud. (common reed) and filter media of different adsorption capacities. Six out of 12 filters received inflow water spiked with metals. For 2 years, hydrated nickel and copper nitrate were added to sieved gully pot liquor to simulate contaminated primary treated storm runoff. For those six constructed wetland filters receiving heavy metals, an obvious breakthrough of dissolved nickel was recorded after road salting during the first winter. However, a breakthrough of nickel was not observed, since the inflow pH was raised to eight after the first year of operation. High pH facilitated the formation of particulate metal compounds such as nickel hydroxide. During the second year, reduction efficiencies of heavy metal, 5-days at 20 degrees C N-Allylthiourea biochemical oxygen demand (BOD) and suspended solids (SS) improved considerably. Concentrations of BOD were frequently < 20 mg/L. However, concentrations for SS were frequently > 30 mg/L. These are the two international thresholds for secondary wastewater treatment. The BOD removal increased over time due to biomass maturation, and the increase of pH. An analysis of the findings with case-based reasoning can be found in the corresponding follow-up paper (Part B).
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Jong, T. (2006). Microbial sulfate reduction under sequentially acidic conditions in an upflow anaerobic packed bed bioreactor. Water Research, 40(13), 2561–2571.
Abstract: The aim of this study was to operate an upflow anaerobic packed bed reactor (UAPB) containing sulfate reducing bacteria (SRB) under acidic conditions similar to those found in acid mine drainage (AMD). The UAPB was filled with sand and operated under continuous flow at progressively lower pH and was shown to be capable of supporting sulfate reduction at pH values of 6.0, 5.0, 4.5, 4.0 and 3.5 in a synthetic medium containing 53.5 mmol l(-1) lactate. Sulfate reduction rates of 553-1052 mmol m(-3) d(-1) were obtained when the influent solution pH was progressively lowered from pH 6.0 to 4.0, under an optimal flow rate of 2.61 ml min(-1). When the influent pH was further lowered to pH 3.5, sulfate reduction was substantially reduced with only about 1% sulfate removed at a rate of 3.35 mmol m(-3) d(-1) after 20 days of operation. However, viable SRB were recovered from the column, indicating that the SRB population was capable of surviving and metabolizing at low levels even at pH 3.5 conditions for at least 20 days. The changes in conductivity in the SRB column did not always occur with changes in pH and redox potential, suggesting that conductivity measurements may be more sensitive to SRB activity and could be used as an additional tool for monitoring SRB activity. The bioreactor containing SRB was able to reduce sulfate and generate alkalinity even when challenged with influent as low as pH 3.5, indicating that such treatment systems have potential for bioremediating highly acidic, sulfate contaminated waste waters. (c) 2006 Elsevier Ltd. All rights reserved.
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Landers, J. (2006). Bioremediation method could cut cost of treating acid rock drainage. Civil Engineering, 76(7), 30–31.
Abstract: The Gilt Edge Mine in South Dakota's Lawrence County was a gold mine that was abandoned later when its recent owner went bankrupt. Seeking a cost-effective method for treating millions of gallons of acid rock drainage (ARD), CDM partnered with Green World Science, Inc. (GWS) of Boise, Idaho, for the development of an in situ bioremediation process that can be used to remove metals from pit lake water. Recent testing revealed that the in situ bioremediation method can successfully remove metals from highly acidic water without the need to construct costly water treatment facilities.
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Fisher, T. S. R., & Lawrence, G. A. (2006). Treatment of acid rock drainage in a meromictic mine pit lake. Journal of environmental engineering, 132(4), 515–526.
Abstract: The Island Copper Mine pit near Port Hardy, Vancouver Island, B.C., Canada, was flooded in 1996 with seawater and capped with fresh water to form a meromictic (permanently stratified) pit lake of maximum depth 350 m and surface area 1.72 km2. The pit lake is being developed as a treatment system for acid rock drainage. The physical structure and water quality has developed into three distinct layers: a brackish and well-mixed upper layer; a plume stirred intermediate layer; and a thermally convecting lower layer. Concentrations of dissolved metals have been maintained well below permit limits by fertilization of the surface waters. The initial mine closure plan proposed removal of heavy metals by metal-sulfide precipitation via anaerobic sulfate-reducing bacteria, once anoxic conditions were established in the intermediate and lower layers. Anoxia has been achieved in the lower layer, but oxygen consumption rates have been less than initially predicted, and anoxia has yet to be achieved in the intermediate layer. If anoxia can be permanently established in the intermediate layer then biogeochemical removal rates may be high enough that fertilization may no longer be necessary. < copyright > 2006 ASCE.
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Potgieter-Vermaak, S. S., Potgieter, J. H., Monama, P., & Van Grieken, R. (2006). Comparison of limestone, dolomite and fly ash as pre-treatment agents for acid mine drainage. Minerals Engineering, 19(5), 454–462.
Abstract: The physical, chemical and biological nature of Vaal Dam water, the main source of water in Gauteng, South Africa, is often affected by underground water pollution (acid mine water) and industrial effluents. The ecological significance and detrimental effects necessitate investigations into treating the water prior to discharge into public streams. Although several acid mine water treatment techniques and methods exist, they all have certain disadvantages. Lime treatment is the most common approach. In this investigation, limestone, dolomite and fly ash were selected as pre-treatment agents based on their low cost. Simulated acid mine water containing these agents was tested using a Jar Test apparatus. Samples were analyzed before and after treatment for pH, ferrous, ferric, calcium, magnesium and sulphate ions. The study demonstrated that the quality of the water improved with an increase in the amount and surface area of the raw material dosed and an increase in contact time. It was also influenced by the chemical composition of the acid mine water and aeration. Chemical cost savings of 38% are achieved when lime is replaced with limestone, and cost savings of 23% and 48% can be accomplished when limestone is substituted with dolomite and fly ash respectively. This could result in significant savings to the gold and coal mining industries, and could lead to a mutual benefit/gain between industrialists/polluters and the public.
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