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Ye, Z. H., Whiting, S. N., Qian, J. H., Lytle, C. M., Lin, Z. Q., & Terry, N. (2001). Trace element removal from coal ash leachate by a 10-year-old constructed wetland. J. Environ. Qual., 30(5), 1710–1719.
Abstract: This study investigated the ability of a 10-yr-old constructed wetland to treat metal-contaminated leachate emanating from a coal ash pile at the Widows Creek electric utility, Alabama (USA). The two vegetated cells, which were dominated by cattail (Typha latifolia L.) and soft rush (Juncus effusus L.), were very effective at removing Fe and Cd from the wastewater, but less efficient for Zn, S, B, and Mn. The concentrations were decreased by up to 99% for Fe, 91% for Cd, 63% for Zn, 61% for S, 58% for Mn, and 50% for B. Higher pH levels (>6) in standing water substantially improved the removing efficiency of the wetland for Mn only. The belowground tissues of both cattail and soft rush had high concentrations of all elements; only for Mn, however, did the concentration in the shoots exceed those in the belowground tissues. The concentrations of trace elements in fallen litter were higher than in the living shoots, but lower than in the belowground tissues. ne trace element accumulation in the plants accounted for less than 2.5% of the annual loading of each trace element into the wetland. The sediments were the primary sinks for the elements removed from the wastewater. Except for Mn, the concentrations of trace elements in the upper layer (0-5 cm) of the sediment profile tended to be higher than the lower layers (5-10 and 10-15 cm). We conclude that constructed wetlands are still able to efficiently remove metals in the long term (i.e., >10 yr after construction).
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Ayala, J., & Fernández, B. (2005). (J. Loredo, & F. Pendás, Eds.). Mine Water 2005 – Mine Closure. Oviedo: University of Oviedo.
Abstract: The objective of this study was to examine the use of flying ash to remove the copper cyanide species from gold mine effluents. In order to discharge them safely with minimum impact to the environment the effluents must be treated in such a way that the legal conditions were attained with the lowest possible cost. This paper presents the treatment of cyanide solution originating from tailing ponds at the end of detoxification by direct contact with flying ash.
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Srivastave, A., & Chhonkar, P. K. (2000). Amelioration of coal mine spoils through fly ash application as liming material. J. Ind. Res., 59(4), 309–313.
Abstract: The feasibility of fly ash as compared to lime to ameliorate the low pH of acidic coal mine spoils under controlled pot culture conditions are reported using Sudan grass (Sorghum studanens) and Oats (Avena sativa) as indicator crops. It is observed that at all levels of applications, fly ash and lime significantly increase the pH of mine spoils, available phosphorus, exchangeable potassium, available sulphur and also uptake of phosphorus, potassium, sulphur and oven-dried biomass of both these test crops. The fly ash significantly decreases the bulk density of coal mine spoils, but, there is no effect on bulk density due to lime application. However, when the spoils are amended with either fly ash or lime, the root growth occurs throughout the material. Fly ash and lime do not cause elemental toxicities to the plants as evidenced from the dry matter production by the test crops. The results indicate that fly ash to be a potential alternative to lime for treating acidic coal mine spoils.
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Canty, G. A., & Everett, J. W. (2006). Injection of Fluidized Bed Combustion Ash into Mine Workings for Treatment of Acid Mine Drainage. Mine Water Env., 25(1), 45–55.
Abstract: A demonstration project was conducted to investigate treating acid mine water by alkaline injection technology (AIT). A total of 379 t of alkaline coal combustion byproduct was injected into in an eastern Oklahoma drift coal mine. AIT increased the pH and alkalinity, and reduced acidity and metal loading. Although large improvements in water quality were only observed for 15 months before the effluent water chemistry appeared to approach pre-injection conditions, a review of the data four years after injection identified statistically significant changes in the mine discharge compared to pre-injection conditions. Decreases in acidity (23%), iron (18%), and aluminium (47%) were observed, while an increase in pH (0.35 units) was noted. Presumably, the mine environment reached quasi-equilibrium with the alkalinity introduced to the system.
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Stewart, B. R. (1996). The influence of fly ash additions on acid mine drainage production from coarse coal refuse. Ph.D. thesis, Virginia Polytechnic Institute and State University,, Blacksburg.
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