Aerobic electrotrophic denitrification coupled with biologically induced phosphate precipitation for nitrogen and phosphorus removal from high-salinity wastewater: Performance, mechanism, and microbial community.

Electrotrophic denitrification (ED) is a promising nitrogen removal technique; however, the potential of ED coupled with biologically induced phosphate precipitation (BIPP) has not been fully explored. In this study, the performances, mechanisms, and microbial communities of the coupled system were investigated. The results showed that excellent nitrogen and phosphorus removal (both exceeding 92 %) was achieved in the salinity range of 20-60 g/L. ED contributed to approximately 83.4 % of nitrogen removal. BIPP removed approximately 63.5 % of the phosphorus. Batch activity tests confirmed that aerobic/anoxic bio-electrochemical and autotrophic/heterotrophic denitrification worked together for nitrate removal. Sulfate reduction had a negative impact on denitrification. Moreover, phosphorus removal was controlled by ED and calcium ions. The alkaline solution environment created by denitrification may greatly promote the formation of hydroxyapatite. Microbial community analyses indicated that the key bacteria involved in aerobic ED was Arcobacter. These findings will aid in the advanced treatment of high-salinity wastewater.