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

Abstract

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 nitri- fying biocathode was developed. Under different solution conductivities (2.33 ± 0.25 mS cm−1 and

4.94 ± 0.55 mS cm−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 48.03A m−3 and 66.26A m−3

were obtained, with the positive energy balance of 4.52 and 7.44Wm−3. In addition, the bio-ECC exhib- ited excellent NH4

+-N removal performance with the nitrogen removal rates of 7.28 mg L−1 h−1 and

6.77 mg L−1 h−1 in cathode chamber, indicating the superiority of bio-ECC in NH4

+-N removal. Pyrose- quencing 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.