Anammox bacteria grow slowly and can be affected by large pH fluctuations. Using suitable buffers could make the start-up of anammox reactors easy and rapid. In this study,the effects of three kinds of buffers on the nitrogen removal and growth characteristics of anammox sludge were investigated. Reactors with CO2/NaHCO3buffer solution（CCBS） performed the best in nitrogen removal, while 4-（2-hydroxyerhyl）piperazine-1-ethanesulfonic acid（HEPES） and phosphate buffer solution（PBS） inhibited the anammox activity. Reactors with 50 mmol/L CCBS could start up in 20 days, showing the specific anammox activity and anammox activity of 1.01±0.10 gN/（gVSS·day） and 0.83±0.06 kgN/（m~3·day）, respectively. Candidatus Kuenenia was the dominant anammox bacteria, with a relative abundance of 71.8%.Notably, anammox reactors could also start quickly by using 50 mmol/L CCBS under nonstrict anaerobic conditions. These findings are meaningful for the quick start-up of engineered anammox reactors and prompt enrichment of anammox bacteria.
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