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Goulet, R. R. (2001). The evaluation of metal retention by a constructed wetland using the pulmonate gastropod Helisoma trivolvis (Say). Archives of Environmental Contamination and Toxicology, 40(3), 303–310.
Abstract: Constructed wetlands are built because they can act as sinks fur many pollutants, thereby protecting the water quality of downstream ecosystems. The treatment performance is generally assessed using mass balance calculations. Along with the mass balance approach, we compared the metal content of populations of a common pond snail (Helisoma trivolvis Say) collected upstream and downstream of a 3-year-old constructed wetland. Snails were collected in early May, June, and August 1998. At the same time, water samples for particulate and dissolved metals were taken every 3 days for the duration of the experiment. Overall, the wetland retained most dissolved metals, including Fe, Mn, Cu, Zn, Ni, and Pb, but released dissolved As. However, the wetland released particulate Fe and Mn. With the exception of Zn, the metal concentrations of the downstream snails were on average higher than those measured in the upstream population. The higher metal content of downstream snails was likely related to the significant export of particulate metals by the wetland, despite the overall retention of dissolved metals. This study points to the need for biological as well as chemical monitoring to determine the treatment efficiency and toxicological risk associated with constructed wetlands.
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Goulet, R. R. (2001). Changes in dissolved and total Fe and Mn in a young constructed wetland: Implications for retention performance. Ecological Engineering, 17(4), 373–384.
Abstract: Surface-flow wetlands are generally considered sinks for Fe and Mn but they may also export and affect the partitioning of these metals. This study was undertaken to evaluate the effect of a young constructed wetland on the retention and transformation of both dissolved and particulate Fe and Mn. Duplicate water samples were collected every three days at the inlet and outlet structures of the Monahan Wetland, Kanata, Ontario, from spring of 1997 to 1999. While on a yearly basis the wetland showed significant retention of che dissolved phase, the retention of total Fe and Mn was poor. There were strong seasonal differences in retention and, during the winter, the wetland was a source. The wetland transformed dissolved into particulate Fe and Mn from spring to fall whereas during the winter, dissolved Fe and Mn were released. Changes in pH, alkalinity and temperature could explain 11% and 40% of the outlet variation in the ratio of dissolved to total Fe and Mn respectively. Furthermore, from spring to late summer, planktonic algal biomass was negatively related to the ratio of dissolved to total Fe and Mn implying a role in Fe and Mn transformations in young wetlands where emergent and submerged vegetation have yet to dominate the system. (C) 2001 Elsevier Science B.V. All rights reserved.
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Govind, R. (2001). Treatment of acid mine drainage using membrane bioreactors. Bioremediation of Inorganic Compounds, 6(9), 1–8.
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.
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Greben, H. A., Matshusa, M. P., & Maree, J. P. (2005). (J. Loredo, & F. Pendás, Eds.). Mine Water 2005 – Mine Closure. Oviedo: University of Oviedo.
Abstract: Mining is implicated as a significant contributor to water pollution, the prime reason being, that pyrites oxidize to sulphuric acid when exposed to air and water. Mine effluents, often containing sulphate, acidity and metals, should be treated to render it suitable for re-use in the mining industry, for irrigation of crops or for discharge in water bodies. This study describes the removal of all three mentioned pollutants in mine effluents, from different origins, containing different concentrations of various metals. The objectives were achieved, applying the biological sulphate removal technology, using ethanol as the carbon and energy source. It was shown that diluting the mine effluent with the effluent from the biological treatment, the pH increased due to the alkalinity in the treated water while the metals precipitated with the produced sulphide. When this treatment regime was changed and the mine water was fed undiluted, it was found that the metals stimulated the methanogenic bacteria (MB) as trace elements. This resulted in a high COD utilization of the MB, such that too little COD was available for the SRB. Metal removal in all three studies was observed and in most instances the metals were eliminated to the required disposal concentration.
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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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