Passive Treatment of Acid Mine Drainage with Limestone

摘要: The water treatment performances of two anoxic limestone drains (ALDs) were evaluated. Anoxic are buried beds that intended to add bicarbonate alkalinity flow-through acid mine drainage. Both ALDs received contaminated with Fe²⁺ (216–279 mg L⁻¹) and Mn (41–51 L⁻¹). Flow through the Howe Bridge ALD increased by an average 128 L⁻¹ (CaCO₃ equivalent) Ca 52 L⁻¹, while concentrations Fe, K, Mg, Mn, Na, SO²⁻₄ unchanged. Morrison 248 111 L⁻¹. Concentrations all decreased 17%, effect attributed dilution uncontaminated water. Iron, which 30%, was partially retained within ALD. Calcite dissolution enhanced at both sites high PCO₂. Untreated waters had calculated PCO₂ values 6.39 kPa (10⁻¹.²⁰ atm) 9.24 (10⁻¹.⁰⁴ atm), respectively. At sites, stabilized undersaturated (SICₐₗcᵢₜₑ = 10⁻¹.² 10⁻⁰.⁸ Morrison) after flowing approximately half beds. second each little additional on chemistry. current rates calcite solubilization, 17.9 kg d⁻¹ CaCO₃ 2.7 Morrison, have theoretical effective lifetimes in excess 20 yr. By significantly increasing waters, metal removal downstream constructed wetlands.