Bioelectrochemical Reaction Kinetics, Mechanisms, and Pathways of Chlorophenol Degradation in MFC Using Different Microbial Consortia

Abstract

Microbial fuel cell (MFC) is a sustainable technology for removing toxic pollutants such as chlorophenols, while generating electricity. Yet, there is lack of detailed study on understanding bioelectrochemical interactions within the complex biological, chemical, and electronic species in MFC system. This paper reports a new research approach to discover bioelectrochemical reaction kinetics, biodegradation pathways, and electrochemical reaction mechanisms of degradation of 2,4-dichlorophenol (2,4-DCP) in MFC, which was inoculated with industrial and domestic microbial consortia, referred to as iMFC and dMFC systems, respectively. The chlorophenol degradation was found to contribute electronic transfer and generation in MFC. Microbial growth and degradation kinetic results analyzed by Michaelis–Menten and Hanes–Woolf models showed that MFC is highly capable of degrading 2,4-DCP at high concentration (>30 mg/L). The biodegradation pathways and metabolites varied significantly in iMFC and dMFC under aerobic/anaerobic conditions. The dMFC demonstrated simple and complete degradation pathways, while complex pathways with more nondegraded metabolites were determined in iMFC. A higher biodegradation rate (>60%, Vmax = 0.32 mg/L/h and Vmax /Ks = 0.03 h–1) was achieved in dMFC, producing less toxic acetate as the final product. The iMFC showed excellent microbial growth (∼0.5 OD, μmax = 0.028 h–1) and higher electric outputs (∼400 mV) with 3-oxoadipate as its end-product.