Nitrogen removal from iron oxide red wastewater via partial nitritation-Anammox based on two-stage zeolite biological aerated filter

Abstract Partial nitritation-anaerobic ammonium oxidation (PN-Anammox) was successfully applied for high-strength ammonium iron oxide red wastewater (IORW) treatment based on stable PN performance of zeolite-biological aerated filter (ZBAF). By separating Na 2 CO 3 dosage avoid the high free ammonia (FA) inhibited nitritation, two-stage ZBAF was applied for achieving efficient PN with Na 2 CO 3 as the alkalinity donor and saving about 40.0% of the alkalinity cost compared to NaHCO 3 . Moreover, Anammox was used for further nitrogen removal from IORW and stable total nitrogen (TN) removal was obtained at the influent NH 4 + -N concentration of 567 mg/L and TN removal efficiency kept above 70.0% after 100 days operation. High throughput sequencing-based approaches showed that Nitrosomoadaceae (AOB) and Kuenenia was dominance in two-stage ZBAF and Anammox samples respectively, while Nitrospire and Nitrobacter (NOB) undetected. The combined process should have advantages for similar high-strength ammonium wastewater treatment.