Carbon cloth self-forming dynamic membrane enhances anaerobic removal of organic matter from incineration leachate via direct interspecies electron transfer

Abstract

Anaerobic dynamic membrane bioreactors (AnDMBRs) can convert organic matter in wastewater to methane with excellent filtration performance, and can effectively intercept suspended solids and macromolecules in wastewater. The objectives of this study were to explore the feasibility of enhancing AnDMBRs by using conductive carbon cloth as the supporting material for self-forming dynamic membrane to treat waste incineration leachate, determine the strengthening efficiency and reactor operation mechanism, and further study the enhancement mechanism. Incineration leachate was treated using a laboratory-scale AnDMBR with either conductive carbon cloth or polyester cloth as the supporting material. Compared with the polyester cloth, the carbon cloth reactor resulted in higher COD removal (96.5% vs 85.5%) and higher methane yield (217 vs 169 mL(STP)/h) when the reactors were fed diluted leachate with COD of 15,000 mg/L. In addition, the carbon cloth r withstood a higher organic load of 5.129 kg COD/(m3d) compared with only 4.014 kg COD/(m3d) for the polyester cloth reactor. A suitable filtering performance was also observed in both reactors, which could effectively intercept > 4000 Da macromolecules, and remove > 97% of dissolved organic matter in the leachate. Electroactive microorganisms including Syntrophomonas and Methanothrix species were enriched on the conductive carbon cloth surface, and genes associated with reduction of CO2 to methane were more highly expressed by Methanothrix cells attached to the carbon cloth than that of the polyester cloth, which possibly accelerated the methanogenesis by direct interspecies electron transfer.