Abstract: Acid drainage waters generated in the copper ore deposit Elshitza. Central Bulgaria, were treated by a natural wetland located in the deposit. The waters had a pH in the range of about 2.5 – 3.5 and contained copper, cadmium, arsenic, iron, manganese and sulphates as main pollutants. The watercourse through the wetland covered a distance of about 100 in and the water flow rate varied in the range of about 0.5 – 2.0 1/s. The wetland was characterized by an abundant water and emergent vegetation and a diverse microflora. Phragmites communis was the prevalent plant species in the wetland but species of the genera Scirpus, Typha, Juncus, Carex and Poa as well as different algae were also well present. It was found that an efficient removal of the pollutants was achieved and their residual concentrations in the wetland effluents were decreased below the relevant permissible levels for water intended for use in the agriculture and/or industry. The removal was clue to different processes but the microbial dissimilatory sulphate reduction and the sorption of pollutants by the organic matter and clay minerals present in the wetland played the main role. Negative effects of the pollutants on the growth and activity of the indigenous plant and microbial communities were not observed.

Abstract: Acid mine drainage (AMD) from abandoned underground mines significantly impairs water quality in the Tones Branch watershed in McCreary Co., Kentucky, USA. A 1022-m(2) surface-flow wetland was constructed in 1989 to reduce the I AMD effects, however, the system failed after six months due to insufficient utilization of the treatment area, inadequate alkalinity production and metal overloading. In an attempt to improve treatment efficiencies, a renovation project was designed incorporating two anoxic limestone drains (ALDs) and a series of anaerobic subsurface drains that promote vertical now or mine water through a successive alkalinity producing system (SAPS) of limestone beds overlain by organic compost. Analytical results from the 19-month post-renovation period are very encouraging. Mean iron concentrations have decreased from 787 to 39 mg l(-1), pH increased from 3.38 to 6.46 and acidity has been reduced from 2244 to 199 mg l(-1) (CaCO3 equivalent). Mass removal rates averaged 98% for Al, 95% for Fe, 94% for acidity, 55% for sulfate and 49% for Mn during the study period. The results indicate increased alkalinity production from limestone dissolution and longer residence time have contributed to sufficient buffering and metal retention. The combination of ALDs and SAPS technologies used in the renovation and the sequence in which they were implemented within the wetland system proved to be an adequate and very promising design for the treatment of this and other sources of high metal load AMD.

Abstract: Acid mine drainage is a severe water pollution problem attributed to past mining activities. The exposure of the post-mining mineral residuals to water and air results in a series of chemical and biological oxidation reactions, that produce an effluent which is highly acidic and contains high concentrations of various metal sulfates. Several treatment techniques utilizing sulfate reducing bacteria have been proposed in the past; however few of them have been practically applied to treat acid mine drainage. This research deals with membrane reactor studies to treat the acid mine drainage water from Berkeley Pit in Butte, Montana using hydrogen-consuming sulfate reducing bacteria. Eventually, the membrane reactor system can be applied towards the treatment of acid mine drainage to produce usable water.