Assessment of sulphate and iron reduction rates during reactor start-up for passive anaerobic co-treatment of acid mine drainage and sewage

Passive co-treatment of municipal wastewater (MWW) and acid mine drainage (AMD) has shown promise over the past decade for simultaneous remediation of these widespread waste streams. To investigate the efficiency and rates of iron and sulphate reduction during the start-up of anaerobic co-treatment using a novel, process-based kinetic modeling approach, twenty-four replicate 1L-cubitainers containing a 5:2 MWW:AMD mixture and Kaldnes plastic media were sealed, incubated and sacrificially sampled for key water quality parameters over 30 days. Alkalinity generation, pH increase and efficient removal of iron, aluminum and phosphate were observed. The observed sulphate and iron reduction rates were relatively slow, and the removal of sulphate, organic carbon and nitrogen was modest and incomplete. Overall, the results confirm the efficacy of AMD-MWW co-treatment for removal of key pollutants, but also highlight factors that may limit this emerging technology.