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Zinck, J. (2006). Icard 2006. St. Louis: Proceedings, International Conference of Acid Rock Drainage (ICARD).
Abstract: Sludge management is an escalating concern as the inventory of sludge continues to grow through perpetual “pump and treat” of acidic waters at mine sites. Current sludge management practices, in general, are ad hoc and frequently do not adress long-term storage, and in some cases, long-term stability. While a variety of sludge disposal practices have been applied, many have not been fully investigated and monitoring data on the performance of these technologies is limited and not readily available. This paper discusses options for treatment sludge management including conventionale disposal technologies and options for reclamation of sludge areas.
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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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Wolkersdorfer, C. (2006). Icard 2006. 7: Proceedings, International Conference of Acid Rock Drainage (ICARD).
Abstract: Acid mine drainage, the drainage of metals, and the prediction of mine water rebound after mine closure are major problems for the mining industry. In the literature, the difficulties in evaluating the hydrodynamics of flooded mines are well described, although only a few tracer tests in flooded mines have been published. Increased knowledge about the hydraulic behaviour of the mine water within a flooded mine might significantly reduce the costs of mine closure and remediation. Relatively cheap and reliable results for decision making can be obtained when tracer tests are properly conducted in a flooded mine prior to planning of remediation strategies or numerical simulations. Applying the results of successful tracer tests allows one to optimise remediation designs and thereby diminish the costs of remediation. The paper summarises the results of several tracer tests and draws general conclusions from such tests.
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Sasaki, K. (2006). Immobilization of Mn(II) ions by a Mn-oxidizing fungus – Paraconiothyrium sp.-like strain at neutral pHs. Mater. Trans., 47(10), 2457–2461.
Abstract: A Mn-oxidizing fungus was isolated from a constructed wetland of Hokkaido (Japan), which is receiving the Mn-impacted drainage, and genetically and morphologically identified as Paraconiothyrium sp.-like strain. The optimum pHs were 6.45-6.64, where is more acidic than those of previously reported Mn-oxidizing fungi. Too much nutrient inhibited fungal Mn-oxidation, and too little nutrient also delayed Mn oxidation even at optimum pH. In order to achieve the oxidation of high concentrations of Mn like mine drainage containing several hundreds g-m(-3) of Mn, it is important to find the best mix ratio among the initial Mn concentrations, inocolumn size and nutrient concentration. The strain has still Mn-tolerance with more than 380 g-m(-3) of Mn, but high Mn(II) oxidation was limited by pH control and supplied nutrient amounts. The biogenic Mn deposit was poorly crystallized birnessite. The strain is an unique Mn-oxidizing fungus having a high Mn tolerance and weakly acidic tolerance, since there has been no record about the property of the strain. There is a potentiality to apply the strain to the environmental bioremediation.
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Conca, J. L., & Wright, J. (2006). An Apatite II permeable reactive barrier to remediate groundwater containing Zn, Pb and Cd. Appl. Geochem., 21(12), 2188–2200.
Abstract: Phosphate-induced metal stabilization involving the reactive medium Apatite II(TM) [Ca10-xNax(PO4)6-x(CO3)x(OH)2], where x < 1, was used in a subsurface permeable reactive barrier (PRB) to treat acid mine drainage in a shallow alluvial groundwater containing elevated concentrations of Zn, Pb, Cd, Cu, SO4 and NO3. The groundwater is treated in situ before it enters the East Fork of Ninemile Creek, a tributary to the Coeur d'Alene River, Idaho. Microbially mediated SO4 reduction and the subsequent precipitation of sphalerite [ZnS] is the primary mechanism occurring for immobilization of Zn and Cd. Precipitation of pyromorphite [Pb10(PO4)6(OH,Cl)2] is the most likely mechanism for immobilization of Pb. Precipitation is occurring directly on the original Apatite II. The emplaced PRB has been operating successfully since January of 2001, and has reduced the concentrations of Cd and Pb to below detection (2 μg L-1), has reduced Zn to near background in this region (about 100 μg L-1), and has reduced SO4 by between 100 and 200 mg L-1 and NO3 to below detection (50 μg L-1). The PRB, filled with 90 tonnes of Apatite II, has removed about 4550 kg of Zn, 91 kg of Pb and 45 kg of Cd, but 90% of the immobilization is occurring in the first 20% of the barrier, wherein the reactive media now contain up to 25 wt% Zn. Field observations indicate that about 30% of the Apatite II material is spent (consumed).
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