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Arango, I. (2002). Evaluation of the beneficial effects of the acidophilic alga Euglena mutabilis on acid mine drainage systems. Ph.D. thesis, Indiana State University,, Terre Haute.
Abstract: Euglena mutabilis is an acidophilic, photosynthetic protozoan that forms benthic mats in acid mine drainage (AMD) channels. At the Green Valley mine, western Indiana, E. mutabilis resides in AMD measuring <4.2 pH, with high concentrations of dissolved constituents (up to 22.67 g/l). One of the main factors influencing E. mutabilis distribution is water temperature. The microbe forms thick (>1 mm), extensive mats during spring and fall, when water temperature is between 13 and 28 degrees C. During winter and summer, when temperatures are outside this range, benthic communities have a very patchy distribution and are restricted to areas protected from extreme temperature changes. E. mutabilis also responds to rapid increases in pH, which are associated with rainfall events. During these events pH can increase above 4.0, causing precipitation of Fe and Al oxy-hydroxides that cover the mats. The microbe responds by moving through the precipitates, due to phototaxis, and reestablishing the community at the sediment-water interface within 12 hours. The biological activities of E. mutabilis may have a beneficial effect on AMD systems by removing iron from effluent via oxygenic photosynthesis, and/or by internal sequestration. Photosynthesis by E. mutabilis contributes elevated concentrations of dissolved oxygen (DO), up to 17.25 mg/l in the field and up to 11.83 mg/l in the laboratory, driving oxidation and precipitation of reduced metal species, especially Fe (II), which are dissolved in the effluent. In addition, preliminary electro-microscopic and staining analyses of the reddish intracellular granules in E. mutabilis indicate that the granules contain iron, suggesting that E. mutabilis sequesters iron from AMD. Inductive coupled plasma analysis of iron concentration in AMD with and without E. mutabilis also shows that E. mutabilis accelerates the rate of Fe removal from the media. Whether iron removal is accelerated by internal sequestration of iron and/or by precipitation via oxygenic photosynthesis has yet to be determined. These biological activities may play an important role in the natural remediation of AMD systems.
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Arnekleiv, J. V., & Storset, L. (1995). Downstream effects of mine drainage on benthos and fish in a Norwegian river; a comparison of the situation before and after river rehabilitation. Heavy metal aspects of mining pollution and its remediation, 52, 35–43.
Abstract: Parts of the Norwegian river Gaula are strongly polluted from former mining activity in the area. In the most polluted parts of the river the concentration levels of Cu and Zn in 1986-1987 were up to 155 mu g l (super -1) and 186 mu g l (super -1) , respectively. In 1989 the spoil heaps in the mining area were covered with protective layers of moss-covered plastic. In 1991-1992 the concentration levels of Cu and Zn had decreased by 75% and 65%, respectively. Animal life in the polluted area seemed to be strongly affected by the trace metals in 1986-1987. The 1991-1992 results showed a marked increase in the number of species and in the number of individuals of each species of Ephemeroptera and Plecoptera, compared with the results from 1986-87. Good correlations were found between the concentrations of Cu in the water and both the number of species and the number of individuals of Ephemeroptera and Plecoptera. Analysis of the species Baetis rhodani, Diura nanseni and Rhyacophila nubila showed an average total dry weight content of Cu up to 264 mu g g (super -1) , of Zn up to 1930 mu g g (super -1) and of Cd up to 16 mu g g (super -1) . The contents of the three trace metals were significantly different from one species to another and in part between the stations for each species. In 1987 trout died after an exposure of one to two days on three test sites in the river, whereas in 1991-1992 40-75% of the trout survived an exposure period of several weeks at two of the sites. Electrofishing in 1991-1992 indicated recolonization of trout in the lower parts of the former affected and uninhabitable area.
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Ashby, J. C. (2001). Injecting alkaline lime sludge and FGD material into underground mines for acid abatement.
Keywords: acid mine drainage; air quality; alkalinity; chemical composition; coal; combustion; discharge; energy sources; gaseous phase; industrial waste; monitoring; pollution; power plants; regulations; remediation; sedimentary rocks; soils; tailings ponds; toxicity; waste disposal 22, Environmental geology
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Aube, B. C., & Zinck, J. M. (1999). Comparison of AMD treatment processes and their impact on sludge characteristics.
Abstract: Lime neutralisation for the treatment of acid mine drainage is one of the oldest water pollution control techniques practised by the mineral industry. Several advances have been made in the process in the last thirty years, particularly with respect to discharge concentrations and sludge density. However, the impact of different treatment processes on metal leachability and sludge handling properties has not been investigated. A study of treatment sludges sampled from various water treatment plants has shown that substantial differences can be related to the treatment process and raw water composition. This study suggests that sludge densities, excess alkalinity, long-term compaction properties, metal leachability, crystallinity and cost efficiency can be affected by the neutralisation process and specific process parameters. The study also showed that the sludge density and dewatering ability is not positively correlated with particle size as previously suggested in numerous studies. The treatment process comparisons include sludge samples from basic lime treatment, the conventional High Density Sludge (HDS) Process, and the Geco HDS Process.
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Aytas, S. O., Akyil, S., Aslani, M. A. A., & Aytekin, U. (1999). Removal of uranium from aqueous solutions by diatomite (Kieselguhr). Journal of Radioanalytical and Nuclear Chemistry, 240(3), 973–976.
Keywords: acid mine drainage; actinides; adsorption; aqueous solutions; clastic rocks; concentration; decontamination; diatomite; experimental studies; isotherms; laboratory studies; metals; pH; physicochemical properties; pollution; remediation; sedimentary rocks; solutes; sorption; techniques; uranium; uranyl ion; waste disposal; waste water 22, Environmental geology
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