[Enhanced Nitrogen Removal of ANAMMOX Treating Saline Wastewater With Betaine Addition].

High salt content could result in the inhibition of microbes and affect biological treatment processes. At present, an important research topic is how to improve the efficiency of biological treatments. The anaerobic ammonia oxidation (ANAMMOX) process was used to treat high saline wastewater. Nitrogen removal performance with betaine was studied by analyzing the ANAMMOX activity, and ammonia nitrogen and nitrate nitrogen removal. The results showed that:① It has obvious improvement when betaine concentration was 0.1-0.4 mmol·L-1. It alleviated the salt stress on bacteria growth inhibition of ANAMMOX, and also promoted the growth of denitrifying bacteria. When betaine concentration was 0.4-0.5 mmol·L-1, denitrifying bacteria was found to have grown greatly. When betaine concentration was greater than 0.5 mmol·L-1, it was unable to alleviate the salt stress inhibiting denitrification efficiency. As a result, betaine concentration of 0.8 mmol·L-1 completely inhibited bacteria. ② When concentration of betaine was 0.3 mmol·L-1, the optimal nitrogen removal efficiency was achieved. NH4+-N and NO2--N increased by 16% and 32%, respectively. Nitrogen removal rate (NRR) increased by 26.8%. ③ At the end of the recovery experiment, with the decreasing concentrations of betaine, NH4+-N was 50.6%, NO2--N was 63.7%, and NRR was 0.65 kg·(m3·d)-1, so the nitrogen removal efficiency underwent fast recovery.