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Evangelou, V. P. (1994). Potential microencapsulation of pyrite by artificial inducement of FePO (sub 4) coatings. In Special Publication – United States. Bureau of Mines, Report: BUMINES-SP-06B-94 (pp. 96–103). Proceedings of the International land reclamation and mine drainage conference and Third international conference on The abatement of acidic drainage; Volume 2 of 4; Mine drainage.
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Fraser, W. W., & Robertson, J. D. (1994). Subaqueous disposal of reactive mine waste; an overview and update of case studies; MEND, Canada. In Special Publication – United States. Bureau of Mines, Report: BUMINES-SP-06A-94 (pp. 250–259). Proceedings of the International land reclamation and mine drainage conference and Third international conference on The abatement of acidic drainage; Volume 1 of 4; Mine drainage.
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Hedin, R. S., Nairn, R. W., & Kleinmann, R. L. P. (1994). Passive Treatment of Coal Mine Drainage. Bureau of Mines Information Circular, Ic-9389, 1–35.
Abstract: Passive methods of treating mine water utilize chemical and biological processes that decrease metal concentrations and neutralize acidity. Compared to conventional chemical treatment, passive methods generally require more land area, but utilize less costly reagents and require less operational attention and maintenance. Currently, three types of passive technologies exist: aerobic wetlands, wetlands that contain an organic substrate, and anoxic limestone drains. Aerobic wetlands promote mixed oxidation and hydrolysis reactions, and are most effective when the raw mine water is net alkaline. Organic substrate wetlands promote anaerobic bacterial activity that results in the precipitation of metal sulfides and the generation of bicarbonate alkalinity. Anoxic limestone drains generate bicarbonate alkalinity and can be useful for the pretreatment of mine water before it flows into a wetland. Rates of metal and acidity removal for passive systems have been developed empirically. Aerobic wetlands remove Fe and Mn from alkaline water at rates of 10-20 g×m-2×d-1 and 0.5-1.0 g×m-2×d-1, respectively.
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Hedin, R. S., Watzlaf, G. R., & Nairn, R. W. (1994). Passive treatment of acid-mine drainage with limestone. J. Environ. Qual., 23(6), 1338–1345.
Abstract: The water treatment performances of two anoxic limestone drains (ALDs) were evaluated. Anoxic limestone drains are buried beds of Limestone that are intended to add bicarbonate alkalinity to flow-through acid mine drainage. Both ALDs received mine water contaminated with Fe2+ (216-279 mg L(-1)) and Mn (41-51 mg L(- 1)). Flow through the Howe Bridge ALD increased alkalinity by an average 128 mg L(-1) (CaCO3 equivalent) and Ca by 52 mg L(- 1), while concentrations of Fe, K, Mg, Mn, Na, and SO42- were unchanged. The Morrison ALD increased alkalinity by an average 248 mg L(-1) and Ca by 111 mg L(-1). Concentrations of K, Mg, Mn, and SO42- all decreased by an average 17%, an effect attributed to dilution with uncontaminated water. Iron, which decreased by 30%, was partially retained within the Morrison ALD. Calcite dissolution was enhanced at both sites by high P- CO2. Untreated mine waters at the Howe Bridge and Morrison sites had average calculated P-CO2 values of 6.39 kPa (10(- 1.20) atm) and 9.24 kPa (10(-1.04) atm), respectively. At both sites, concentrations of bicarbonate alkalinity stabilized at undersaturated values (SICalcite = 10(-1.2) at Howe Bridge and 10(-0.8) at Morrison) after flowing through approximately half of the limestone beds. Flow through the second half of each ALD had little additional effect on mine water chemistry. At the current rates of calcite solubilization, 17.9 kg d(-1) CaCO3 at Howe Bridge and 2.7 kg d(-1) CaCO3 at Morrison, the ALDs have theoretical effective lifetimes in excess of 20 yr. By significantly increasing alkalinity concentrations in the mine waters; both ALDs increased metal removal in downstream constructed wetlands.
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Hellier, W. W., Giovannitti, E. F., & Slack, P. T. (1994). Best professional judgement analysis for constructed wetlands as a best available technology for the treatment of post-mining groundwater seeps. In Special Publication – United States. Bureau of Mines, Report: BUMINES-SP-06A-94 (pp. 60–69). Proceedings of the International land reclamation and mine drainage conference and Third international conference on The abatement of acidic drainage; Volume 1 of 4; Mine drainage.
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