Innovative nitrogen removal process for domestic wastewater treatment

The performances of anaerobic ammonium oxidation(ANAMMOX) process in nitrogen removal from secondary effluent of domestic wastewater were investigated by using a downflow anoxic biofilter.The results showed that ANAMMOX process is suitable for advanced wastewater treatment as well as ammonia-rich wastewater treatment.The relation between ammonium consumption,nitrite consumption and nitrate production could be found to be m(ΔNH4+-N)∶m(ΔNO2--N):m(ΔNO3--N)=1∶(1-1.5):(0.17-0.27),and the consumption of total carbon ranged from 0.3 to 1.3 mg/L during the experiment.The results showed that ammonia removal rate were improved with increasing nitrite concentration,and the reactor rate reached a climax at 118.4 mg/L of nitrite nitrogen concentration.Beyond the concentration,the ANAMMOX process was significantly inhibited though the ANAMMOX bacteria still showed a relatively high activity.The data also indicated that the proper ratio of m(NO2——N):m(NH4+-N) in influent was 1.3∶1 to achieve excellent nitrogen removal.Besides,the data suggested that the pH could be used as an indicator to monitor the course of ANAMMOX reaction in biofilter.The pH increased steadily with the ANAMMOX reaction,and stopped changing as the reaction finished.