Banana peel fermentation broth as a viable alternative carbon source for biological sulfate reduction in acid mine drainage

BACKGROUNDAcid mine drainage (AMD) is a major environmental threat in mining areas due to its strong acidity, high concentrations of sulfate, and heavy metals. Utilizing sulfate-reducing bacteria (SRB) to reduce SO42- and remove heavy metals is a promising and economical AMD treatment. However, AMD lacks sufficient electron donors for sulfate reduction. Banana peel fermentation broth, containing various small-molecule organic acids, is an effective alternative carbon source for SRB, promoting the use of agricultural waste in environmental remediation. This study aims to investigate the impact of adding banana peel fermentation broth to the bioreactor on pollutant removal performance and analyze its effect on the microbial community structure.RESULTSThe bioreactor utilising banana peel fermentation broth as an electron donor, demonstrated the effective removal of various pollutants, including sulfate (55.7%), Cu2+ (90.74%), Mn2+ (70.77%), Fe2+ (81.28%) and Cd2+ (100.00%), with an average reduction of 74.20% in chemical oxygen demand (COD). Sulfate reduction resulted in an increase in pH from 5.5 to 7.9. Microbial community structure analysis revealed that the primary genera involved in sulfate reduction were Desulfurispora and Desulfovibrio, while Delftia contributes to the immobilization of heavy metals. Additionally, the key genera responsible for fermentation to produce small molecule acids were Leptolinea and Sedimentibacter. In symbiosis with SRB, they play a crucial role in the removal efficiency of metals and sulfate.CONCLUSIONThe overall sulfate and heavy metals removal efficiency was found to be satisfactory after 30 days of continuous reactor operation. There was a notable increase in microbial abundance and community diversity within the reactor. Therefore, banana peel fermentation broth is a promising alternative organic carbon source in acid mine drainage(AMD) treatment. (c) 2025 Society of Chemical Industry (SCI).