Chracteristics of anaerobic ammonium oxidation initated by anaerobic granular sludge

Two different mixed sludge, anaerobic granular sludge(Ｒ1) and anaerobic granular sludge with mature anaerobic ammonium oxidation (ANAMMOX) sludge (Ｒ2 )were used as the inocula in two up-flow reactors to enrich anaerobic ammonia-oxidizing bacteria (AnAOB)，respectively．The total nitrogen removal rate of Ｒ1 reached 74% in 99 days, while Ｒ2 remained above 70% in only 48 days．The content of extracellular polymeric substance (EPS) in the sludge was found to increase with the increase of the influent nitrogen loading，which might attribute to the sludge granulation．It was interesting to notice that the dominant AnAOB genera in two systems were different，i．e．Candidatus Kuenenia (7.92%) inＲ1，and Candidatus Brocadia (15.64%) inＲ2．Candidatus Kuenenia also existed in Ｒ2，accounting for 3.02%．Ｒ1 maintained considerable denitrification efficiency in the case of lower anaerobic ammonium oxidizing bacteria abundance and might have more potential for long-term culture．