No abstract

Traditional denitrification often produces high operating costs and excessive sludge disposal expenses due to conventional carbon sources. And Fe0 reactivity enhancement methods are complex and hazardous. Researchers are interested in prolonging the release of Fe2+, Fe3+, and H+ from Fe0 corrosion, accelerating the reduction of Fe3+ to Fe2+, and reactors' hydraulic retention time (HRT). Novel coupling of electric-magnetic field (MF) with Fe0 and C-Fe0 powder in an upflow microaerobic sludge reactor (UMSR) proved excellent in removing nitrogen from wastewater without organic carbon resources. In the current study, the reactor was operated for 78 ± 2 days, divided into five stages (without Fe0, with Fe0, coupling with MF, without coupling with MF, and coupling with MF again), at a hydraulic retention time (HRT) of 2.5 hours, with an influent loading of ammonium (NH4+-N) 50 ± 2 mg/L, at 25°C–27°C, and less than 1.0 mg/L dissolved oxygen (DO). After coupling the electric (MF) 48mT with Fe0, the removal efficiencies were enhanced by 76% for (NO3−-N) with an effluent concentration of 8.7 mg/L, 72% for (NH4+-N) with an effluent concentration of 13.6 mg/L, and 76% for total nitrogen removal (TN), respectively. The sludge was rich in ammonia-oxidizing bacteria, heterotrophic nitrifying bacteria, and denitrifying bacteria. After coupling (MF) with Fe0, the denitrification bacteria community underwent the most substantial change.