Simultaneous electricity generation and eutrophic water treatment utilizing iron coagulation cell with nitrification and denitrification biocathodes

Anthropogenic nutrients released into water induce eutrophication and threaten aquatic life and human health. In this study, an Fe anode coagulation cell with nitrification and denitrification biocathodes was constructed for power generation and algae and nutrient removal. The nitrification and denitrification biocathodes achieved maximum power densities of 6.0 and 6.6 W/m³, respectively. The algae (99.2 ± 0.5%), phosphate (97.4 ± 0.6%), and ammonia (23.1 ± 0.2%) were removed by a spontaneous electrocoagulation process in the anode chamber. In the nitrification biocathode chamber, 95.3 ± 1.4% of the ammonia was oxidized within 6 h, and 88.2 ± 2.5% of the nitrate was removed in 10 h in the denitrification biocathode chamber. The microbial community analysis revealed that ammonia removal was attributed to nitrifying bacteria, including Acinetobacter sp., Phycisphaera sp., and Nitrosomonas sp., and the dominant denitrifying bacteria in the denitrifying biocathode chamber were Planococcus sp., Exiguobacterium sp., and Lysinibacillus sp. In this study, the combination of Fe anodes and biocathodes is shown to afford an efficient method for the simultaneous algae and nutrient removal and power generation.