Enhanced removal of nitrate, nickel, and ibuprofen from immobilized bioreactors by tourmaline/biochar-modified polyurethane sponges.

Currently, the biological treatment of combined-pollutant chemical wastewater has become a research hotspot and challenge. In this study, tourmaline (Tm)- and coconut shell biochar (CB)-modified polyurethane sponges (TCBPs) loaded with Stutzerimonas sp. YX13 were prepared to construct an immobilized bioreactor. Under optimal operating conditions, the removal efficiencies of nitrate (NO3--N), phosphate (PO43--P), calcium (Ca2+), nickel (Ni2+), and ibuprofen (IBU) in this reactor reached 91%, 89%, 78%, 97%, and 96%, respectively. The research suggested that TCBPs materials enhanced electron transfer rates within the system, thereby increasing bacterial metabolic activity and nitrogen removal performance. In addition, Tm stimulated microorganisms to secrete more extracellular polymeric substances (EPS) to promote pollutant removal. The characterization results indicated that PO43--P, Ca2+, Ni2+ and IBU were primarily removed through coprecipitation and adsorption. Community structure analysis indicated that Pseudomonas was the dominant bacterium throughout all stages of the reactor. KEGG results demonstrated that pollutant addition inhibited the expression of denitrification-related genes. This study provides a novel reference for treating combined pollutants from chemical wastewater through microbial-induced calcium precipitation.