Start-up Strategies for Anaerobic Ammonia Oxidation (Anammox) in In-Situ Nitrogen Removal from Polluted Groundwater in Rare Earth Mining Areas

The tremendous input of ammonium and rare earth element (REE) ions released by the enormous consumption (NH4)2SO4 in situ leaching for ion-adsorption RE mining caused serious ground surface water contamination. Anaerobic oxidation (anammox) was a sustainable technology that can reduce this nitrogen pollution. In research, situ, semi ex method inoculation included low-concentration (0.02 mg·L?1) high-concentration (0.10 lanthanum (La)(III) were adopted to explore effective start-up strategies starting up anammox reactors seeded with activated sludge sludge. refrigerated 30 days at 4 °C investigate effects La(III) during period low-temperature. results showed enrichment addition reduced length time required reactivate until it reached state stable activity high removal efficiency 60–71 days. promoted formation floc compact structure enabled resist adverse low temperature so maintain abundance AnAOB microbacterial community diversity refrigeration period. concentration cellular percentage decrease from 54.60 ± 6.19% 17.35 6.69% an unrecoverable level post-refrigeration.