Large-scale switchable potentiostatically controlled/microbial fuel cell bioelectrochemical wastewater treatment system

Abstract

The treatment of municipal wastewater is an energy-intensive process, with the delivery of oxygen as an electron acceptor accounting for a significant share of the total energy consumption. Microbial communities growing on polarized electrodes can facilitate wastewater treatment processes by exchanging electrons with the electrodes. As a new approach, we combined the use of polarized electrodes with microbial fuel cells (MFCs) to develop a switchable dual-mode bioelectrochemical wastewater treatment system. In this system, we first enriched microbial communities on polarized anodes and cathodes. After enrichment, the system was switched to either a self-powered MFC (SP-MFC) mode or a potentiostatically controlled (PC) mode. The system was evaluated at the laboratory scale (260 L, 4 anode and cathode pairs) and the pilot scale (1200 L, 16 anode and cathode pairs). PC and SP-MFC systems showed improved COD removal relative to control (41.6 ± 3.5 and 38.4 ± 3.1 vs 28.8 ± 2.1 mg L−1 d−1, respectively). The laboratory-scale system was operated without biological or electrical interruption for one year. Finally, specific enrichment of active microbial communities was observed on PC anodes in comparison to mixed-operation and non-polarized control anodes. The combined PC and SP-MFC systems allowed us to develop a sustainable and failure-free bioelectrochemical wastewater treatment system.