Evaluation of six types of agricultural waste for utilization in sulfate-reducing bioreactors: Batch and...

Abandoned acid mine drainage (AMD) poses severe threats to ecosystems and human health due to strong acidity and high concentrations of heavy metals. This study investigates the applicability of low-cost agricultural wastes as alternative carbon sources for sulfate-reducing bacteria (SRB) in treating simulated abandoned AMD. The feasibility and mechanisms of a combined SRB and anaerobic limestone bed system for AMD treatment were systematically examined in winter (15-20 °C). Results demonstrated that the oxidation-reduction potential (ORP) of the combined system increased from -231 mV to -325 mV, maintaining a stable reducing environment, with a SO₄^2- removal rate of about 92%, and removal rates of Fe, Cu, and Zn exceeding 98%. Furthermore, a dosing model correlating chemical oxygen demand (COD) addition with sulfate reduction efficiency was established. This study highlights the effectiveness of various low-cost agricultural waste materials as alternative carbon sources for SRB and provides a valuable reference for the application of SRB-coupled anaerobic limestone bed systems in abandoned AMD treatment.