抄録
Recently, nitrite has been recognized as one of the considerable inhibitors of biological phosphorus removal. In fact, there are several reports on inhibitory effect of nitrite. While unfortunately, the reported critical levels of nitrite widely spread. So the real effect of nitrite has not yet been well understood. In this study, several batch tests were conducted to obtain stable and quantitative relation between the size of nitrite exposure and the size of inhibition. The obtained results are as follows; 1) Nitrite inhibits aerobic phosphate uptake of PAOs, but the inhibition is not direct inhibition by nitrite but indirect inhibition caused by reduced respiration, 2) PAOs with higher anoxic activity can reduce the inhibitory effect of nitrite, possibly because of aerobic nitrite denitrification, 3) Nitrite inhibition of aerobic phosphate uptake is successfully expressed by the model including aerobic nitrite denitrification rates. These results strongly suggest that unstable nitrite inhibition of aerobic phosphate uptake is caused by widely distributed anoxic activities of PAOs.
