Simultaneous algae-polluted water treatment and electricity generation using a biocathode-coupled electrocoagulation cell (bio-ECC).

How to utilize electrocoagulation (EC) technology for algae-polluted water treatment in an energy-efficient manner remains a critical challenge for its widespread application. Herein, a novel biocathode-coupled electrocoagulation cell (bio-ECC) with sacrificial iron anode and nitrifying biocathode was developed. Under different solution conductivities (2.33±0.25mScm-1 and 4.94±0.55mScm-1 ), the bio-ECC achieved almost complete removal of algae cells. The maximum power densities of 8.41 and 11.33Wm-3 at corresponding current densities of 48.03Am-3 and 66.26Am-3 were obtained, with the positive energy balance of 4.52 and 7.44Wm-3 . In addition, the bio-ECC exhibited excellent NH4 + -N removal performance with the nitrogen removal rates of 7.28mgL-1 h-1 and 6.77mgL-1 h-1 in cathode chamber, indicating the superiority of bio-ECC in NH4 + -N removal. Pyrosequencing revealed that nitrifiers including Nitrospira, Nitrobacter, Nitrosococcus, and Nitrosomonas were enriched in biocathode. The removal mechanisms of algae in anode chamber were also explored by AFM and SEM-EDX tests. These results provide a proof-of-concept study of transferring energy-intensive EC process into an energy-neutral process with high-efficiency algae removal and electricity recovery.