Study on the new slow-release carbon source biochemistry and its improvement of SRB on the acid mine drainage treatment

The content of sulfate and heavy metals in acidic mine drainage (AMD) exceeds the standard severely, and the acidity is extremely high, causing serious harm to the environment. SRB can efficiently remove sulfates through its own metabolism. The treatment of AMD by SRB faces problems such as carbon source scarcity and heavy metal ion toxicity to SRB. In this study, corn cob and polycaprolactone were embedded to prepare a novel slowrelease carbon source (PSCL), which simultaneously achieves carbon source supply and metal ion removal. Through adsorption isotherms, kinetics, thermodynamics studies, and various characterization analyses, it is known that PSCL removes Cu2+ and Zn2+ through ion exchange, physical and chemical adsorption, electrostatic attraction, and surface complexation. PSCL carbon release experiments and characterization results confirm that its surface carbon distribution is dense, the molecular weight of DOM in the leachate is small, the degree of humification is low, and it has a porous structure, making it a good carbon release material and biological attachment. The experimental results of PSCL enhanced SRB treatment of AMD showed that the removal rates of SO42- , Cu2+ and Zn2+ could be increased to 97.48%, 98.11% and 90.42%, respectively, with a effluent pH of 7.05, effectively improving the water quality of AMD. This study provides new materials and methods to address the limitations of SRB in treating actual AMD.