Catalytic membrane cathode integrated in a proton exchange membrane-free microbial fuel cell for coking wastewater treatment

Background

Coking wastewater (CW) is characterized by complex composition, high concentration and toxicity, thereby challenging the treatment technologies. Traditional microbial fuel cell (MFC) is deficient in effluent quality and capital cost. Therefore, integrating the catalytic electrode membrane in separation process in MFC is promising for actual wastewater treatment, while replacing proton exchange membrane (PEM) to reduce cost.

Methods

A CNF-CFO/PM membrane (blended with carbon nanofiber-CoFe₂O₄, polyvinylidene fluoride) was prepared via casting and phase inversion. By using this membrane as cathode, activated carbon-loaded electrogenic bacteria as bio-anode, the catalytic membrane cathode-MFC system (CM-MFC) was constructed with quartz sand separating layer (QSL) replacing PEM.

Significant findings

Modification with CNF-CFO catalyst effectively improved the catalytic and anti-fouling (membrane foulants) property of membrane cathode. The optimal activity of CM-MFC was achieved under 36 h (HRT), with the COD decreasing from 4325.0-5074.3 mg L⁻¹ to 50.0-92.8 mg L⁻¹, and the stable output voltage of ∼0.40 V. The high-throughput sequencing results clarified that the enriched electrogenic bacteria coexisted with other anaerobic bacteria in the anodic chamber and functioned for electron transfer and organics removal. Integrating with the catalysis and filtration processes of membrane cathode, the effluent quality after primary treatment in the anodic chamber was further enhanced.