The effect of phosphate concentration on nitrification was studied by using a stabilization nitrosation system, which was started up in a continuous flow reactor by inoculating sludge from a municipal wastewater treatment plant. The results showed that the nitrification system was started successfully after operating for 14 days. The conversion rate of ammonia nitrogen reached 92.2%, the nitrite accumulation rate was 73.66%, and the nitrite generation rate was 14.42 g·(m3·d)-1. There was no effect of phosphate concentration on the nitrosation system between 10 and 30 mg·L-1; and the conversion rate of ammonia nitrogen was decreased with the continuous increase in phosphate concentration. When the concentration of phosphate was 80 mg·L-1, with an ammonia conversion rate 13.6%, accumulation rate of nitrite of 18.19%, and nitrite generation rate of 0.54 g·(m3·d)-1, the reaction was severely inhibited. After reducing the influent phosphate concentration to 0, with the ammonia nitrogen conversion rate at more than 80%, nitrite accumulation rate improved to 86.96%, and the nitrite generation rate being 15.63 g·(m3·d)-1, the system recovered after operating for 14 days.
Keywords: continuous flow; inhibition; nitrosation system; phosphate; recovery.