###### Abstract  
After the anaerobic digestion of livestock manure, high concentrations of nutrients still remain. Treatment of livestock wastewater through partial nitrification coupled with anaerobic ammonium oxidation (ANAMMOX) could be a useful technology depending on the investigation of microorganism enrichment and partial nitrification coupled with achievement of the ANAMMOX process. The results show 78.4% and 64.7% nitrite accumulation efficiency was successfully obtained in an intermittent aeration sequencing batch reactor and a continuous aeration sequencing batch reactor, respectively, at a loading rate of 0.93 kg ammonium/(m\({}^{3}\).d). The main reason for the high nitrite accumulation efficiency was the intermittent aeration strategy which generated a 20-30 min lag reaction for nitrite oxidation and promoted the growth of the dominant ammonium oxidation bacteria (_Nitrosomonas_). Non-biodegradable organic matter in the effluents of partial nitrification did not have obvious influence on ANAMMOX activity at low loading rates (118 \(\pm\) 13 mg COD/L and 168 \(\pm\) 9 mg COD/L), and up to 87.4% average nitrite removal rate was observed. However, with the influent COD concentration increasing to 242 \(\pm\) 17 mg/L, the potential inhibition of ANAMMOX activity was exerted by non-biodegradable organic matter.  
Livestock wastewater; partial nitrification; ANAMMOX; non-biodegradable organic matter; nitrogen removal; microbial community  
1  
high concentrations of ammonium and non-biodegradable organic matter in the livestock wastewater were unfavorable for partial nitrification. Thus, effective control strategies should be developed and investigated to achieve stable nitrification.  
Anaerobic ammonium oxidation (ANAMMOX) has been considered as an effective technology for the reduction of accumulated nitrite by oxidation of ammonium rather than organic carbon [9]. In the ANAMMOX process, bacteria grow with bicarbonate as the sole carbon source. Thus, without the need for organic matter, this technology has been exploited to treat nitrogen-rich wastewater, such as landfill leachate, animal manure and supernatant of digested sludge [10; 11]. ANAMMOX bacteria are considered to be difficult to cultivate because of their low specific growth rate (\(\mu_{\text{max}}\) = 0.065/d) and sensitivity to organic matter, which could induce the inhibition of ANAMMOX enrichment [12]. Thus, the non-biodegradable organic matter withdrawn from partial nitrification reactors should be an important issue on the successful use of ANAMMOX for treating livestock wastewater.  
In livestock wastewater, there is not enough biodegradable organic matter for the conventional biological nitrogen removal process. Thus, partial nitrification coupled with ANAMMOX was considered to be an efficient combined technology for nitrogen removal. In this research, in order to evaluate the influences of non-biodegradable organic matter and control strategies on livestock wastewater treatment efficiency, long-term partial nitrification coupled with ANAMMOX reactors were established via microbial community analysis to investigate the performance of nitrogen removal from the livestock wastewater.