Performance of a SAPS-Based Chemo-Bioreactor Treating Acid Mine Drainage Using Low-DOC Spent Mushroom Compost, and Limestone as Substrate

Static and continuous experiments were carried out in a down flow chemo-bioreactor, modeled on successive alkalinity producing systems, for acid mine drainage treatment. Spent mushroom compost (SMC) was used as the immobilizing substrate and nutrient source for sulfate reducing bacteria (SRB). Operational success was assessed using effluent to influent ratios during continuous flow; these averaged: 0.0175, 0.12, and 0.071 for Fe, Cu, and Mn, respectively, and 0.11 for sulfate. In contrast, Mg was released by the SMC, increasing its concentration in the effluent. Acidity was consistently less than 1 mg/L. The pH of the effluent was higher than 7 for most of the experiment. SMC was shown to release sufficient organic carbon during the experiment to establish and maintain anaerobic conditions and sustain the SRB.