Effects of Cattails and Hydraulic Loading on Heavy Metal Removal from Closed Mine Drainage by Pilot-Scale Constructed Wetlands

This study demonstrated heavy metal removal from neutral mine drainage of a closed in Kyoto prefecture pilot-scale constructed wetlands (CWs). The CWs filled with loamy soil and limestone were unplanted or planted cattails. hydraulic retention time (HRT) the was shortened gradually 3.8 days to 1.2 during 3.5 months operation. A short HRT sufficient achieve effluent standard for Cd (0.03 mg/L). cattail-planted reduced average concentrations 0.031 0.01 0.005 mg/L, Zn 0.52 0.14 0.08 Cu 0.07 0.04 0.03 As 0.011 0.006 respectively. Heavy metals removed mainly by adsorption both CWs. biological concentration factors cattails over 2 Cd, Zn, Cu. translocation all 0.5–0.81. Sulfate-reducing bacteria (SRB) belonging Deltaproteobacteria detected only CW. Although minor sink, plants contributed rhizofiltration incubation SRB, possibly producing sulfide precipitates rhizosphere.