A continuous pilot-scale system using coal-mine drainage sludge to treat acid mine drainage contaminated with high concentrations of Pb, Zn, and other heavy metals

► Coal mine drainage sludge can effectively neutralize and treat the acidic drainage for a long time. ► We suggest that the continuous pilot system having CMDS can not only high removal efficiencies, but also high total rates for all heavy metals. ► The pilot system can have a much higher Zn(II) loading rate than other referenced systems such as wetland coupled with algal mat and anoxic limestone drain.