Simultaneous removal of ammonia nitrogen, recovery of phosphate, and immobilization of nickel in a polyester fiber with shell powder and iron carbon spheres bioreactor: Optimization and pathways mechanism

Composite pollutants are prevalent in wastewater, whereas, the simultaneous accomplishment of efficient nitrogen removal and resources recovery remains a challenge. In this study, a bioreactor was constructed to contain Pseudomonas sp. Y1 using polyester fiber wrapped with shell powder and iron carbon spheres, achieving ammonia nitrogen (NH 4 + -N) removal, phosphate (PO 4 3– -P) recovery, and nickel (Ni 2+ ) immobilization. The optimal performance of bioreactor was average removal efficiencies of NH 4 + -N, PO 4 3– -P, calcium (Ca 2+ ), and Ni 2+ as 82.42, 96.67, 76.13, and 98.29% at a hydraulic retention time (HRT) of 6 h, pH of 7.0, and influent Ca 2+ and Ni 2+ concentrations of 100.0 and 3.0 mg L −1, respectively. The bioreactor could remove PO 4 3– -P, Ca 2+, and Ni 2+ by biomineralization, co-precipitation, adsorption, and lattice substitution. Moreover, microbial community analysis suggested that Pseudomonas was the predominant genus and had possessed tolerance to Ni 2+ toxicity in wastewater. This study presented an effective method to synchronously remove NH 4 + -N, recover PO 4 3– -P, and fix heavy metals through microbially induced carbonate precipitation (MICP) and heterotrophic nitrification and aerobic denitrification (HNAD) technology.