Coupling process and mechanism of methanol oxidation and nitrate reduction in an anodic denitrification microbial fuel cell(AD-MFC)

Abstract

An anodic denitrification MFC(AD-MFC)was constructed by inoculating denitrifying bacteria enrichment culture into anode chamber of a dual-chamber MFC, and its capacity of denitrification and electricity production was investigated with methanol as electron donor and nitrate as acceptor in a batch cultivation mode. When initial nitrate and COD concentration were (100.22 ± 0.62)mg·L and (500.40 ± 1.67)mg·L, the volumetric nitrogen and COD removal rates reached 0.31 kg N·m·d and 1.06 kg COD·m·d, respectively, coupled with the maximum voltage of (602.80±5.42)mV and the maximum power density of (908.42 ± 0.07)mW·m. The results demonstrated that power generation in the AD-MFC was due to a coupling of methanol oxidation and nitrate reduction, and voltage changes were closely related to denitrification, indicating the course of denitrification. Voltage curves of the AD-MFC showed three-phase characteristics of descend phase, ascend phase and redescend phase, which could be ascribed to the succession of denitrification, methanol degradation and cell hydrolysate fermentation as dominant reaction in the anolyte.