Groudev, S. N. (2002). Treatment of acid mine drainage by a natural wetland. Wetlands and Remediation Ii, , 133–139.
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.
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Groudev, S. N., Georgiev, P. S., Spasova, I. I., & Nicolova, M. N. (2000). In situ treatment of mine waters by means of a permeable barrier. Groundwater 2000, , 417–418.
Abstract: Acid ground waters contaminated with radioactive elements (U, Ra, Th), toxic heavy metals (Cu, Zn, Cd, Mn, Fe), arsenic and sulphates were treated by means of a permeable barrier. The barrier was filled with a mixture of biodegradable solid organic substrates (spent mushroom compost, sawdust and cow manure) and was inhabited by a mixed microbial community consisting of sulphate-reducing bacteria and other metabolically interdependent microorganisms. An efficient removal of the pollutants was achieved by this barrier during the different climatic seasons, even at ambient temperatures close to degrees C. The microbial dissimilatory sulphate reduction and the sorption of pollutants by the organic matter in the barrier were the main processes involved in this removal.
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