Excess nitrogen accumulation in activated sludge in sequencing batch reactor with a single-stage oxic process

摘要

It was occasionally found that a significant nitrogen loss in solution under neutral pH value in ansequencing batch reactor with a single-stage oxic process using synthetic wastewater, and thennfurther studies were to verify the phenomenon of nitrogen loss and to investigate the pathway ofnnitrogen removal. The result showed that good performance of nitrogen removal was obtained innsystem. 0–7.28mgL21 ammonia, 0.08–0.38mgL21 nitrite and 0.94–2.12mgL21 nitrate werendetermined in effluent, respectively, when 29.85–35.65mgL21 ammonia was feeding as the solennitrogen source in influent. Furthermore, a substantial nitrogen loss in solution (95% of nitrogenninfluent) coupled with a little gaseous nitrogen increase in off-gas (7% of nitrogen influent) wasndetermined during a typical aerobic phase. In addition, about 322mg nitrogen accumulation (84%nof nitrogen influent) was detected in activated sludge. Based on nitrogen mass balancencalculation, the unaccounted nitrogen fraction and the ratio of nitrogen accumulation innsludgeitrogen loss in solution were 14.6mg (3.7% of nitrogen influent) and 0.89, respectively.nThe facts indicated that the essential pathway of nitrogen loss in solution in this study wasnexcess nitrogen accumulation in activated sludge.