Abstract
For the purpose of zinc removal of mine water, we have developed a system of lactate solution feeding as organic liquid instead of organic solids, with the aim to keep the reductive conditions and promote sulfate-reducing bacteria activity of wetland. The experiment was conducted in outdoor condition using mine water containing zinc (2.4±0.9mg/l) with a controlled flow rate of 0.2 m3/m2/day for 2 years. Lactate feeding to anaerobic wetland system was controlled by redox potential to maintain desirable Eh for Sulfate reducing bacteria (SRB). The Eh was maintained at -22±268mV when lactate feeding was manually controlled. A stronger redox condition, -165±118mV was achieved by automatic control, resulting in an improvement in zinc removal efficiency from 88% to 93%. Total zinc concentration in bottom layer of wetland near influent entrance was high and the ratio of exchangeable fraction occufied 61%. Although zinc concentration of effluent became higher under low temperature of water, high redox potential and weak acidic pH, it was suggested that zinc removal efficiency was not affected significantly and performance was stable sufficiently.
