Successful bio-electrochemical treatment of nitrogenous mariculture wastewater by enhancing nitrogen removal via synergy of algae and cathodic photo-electro-catalysis

Systems with catalytic cathode in microbial fuel cell can achieve high treatment efficiency enhanced by the cathode. Such bio-electrochemical systems have potential applications in treating high-salinity nitrogenous mariculture wastewater. For sustainable development of the mariculture industry, enhancing inorganic nitrogen removal is of vital importance due to the low carbon to nitrogen (C/N) ratio of wastewater and strict discharge standard. Herein, simulated mariculture wastewater (high salinity, low COD/N ratio of 0.5–1.0) was successfully treated in an integrated self-biased bio-electrochemical system, with catalyst (TiO2/Co-WO3/SiC) on the cathode and natural-grown algae in the cathode chamber. Satisfactory nitrogen removal (94.05% NH4+-N and 77.35% inorganic nitrogen) and favorable 76.66% removal of organics (UV254) were both achieved, with visible light illumination. The NH4+-N in the effluent was below 2 mg L−1. The synergy of bacteria, algae and cathode, promoted pollutant removal, and made the system sustainable and efficient in treating mariculture wastewater. [Display omitted] •Novel cathode with TiO2/Co-WO3/SiC enhanced photo-electrocatalytic nitrogen removal•A system with bacteria-algae-catalytic cathode and bio-anode was constructed.•From mariculture wastewater, the system removed 94.05% NH4+-N at effluent 2 mg L−1.•The system removed 77.35% inorganic nitrogen and 76.66% organic pollutant.•There is synergy of bacteria-algae-catalytic electrode, photo and bio-electricity.