A/O中试工艺中亚硝酸氮积累现象的消失与重现

DISAPPEARANCE AND RECURRENCE OF NITRITE ACCUMULATION IN PILOT-SCALE A/O PROCESS

应用A/O工艺处理低C/N比的生活污水,SRT维持在15d左右,水温控制在21—25℃,pH值在7·2—7·6之间,污泥浓度为2500—4500mg·l-1,通过控制溶解氧(DO)浓度实现了亚硝酸氮积累、消失和重现.维持较低的DO浓度(≤0·7mg·l-1)可使亚硝酸氮积累现象重现.在两次试验的比较中,亚硝酸氮积累破坏的愈彻底相应恢复的过程就愈漫长.在长期较低的DO浓度条件下,亚硝酸菌充分利用了有限的溶解氧,在与丝状菌竞争DO中占到优势,因此,污泥沉淀性能很好,没有产生严重污泥膨胀.同时分析了pH值、游离氨(FA)浓度、温度等对亚硝酸氮积累的影响,DO是影响亚硝酸氮积累的关键因素.

Wastewater of low C/N ratio was treated by A/O process, SRT was about 15 days, the temperature, pH and MLSS were between 21℃ to 25℃, 7.2 to 7.6, 2500 to 4500mg·l^ -1 respectively. The experiment achieved nitrite accumulation, disappearance and recurrence by controlling the DO concentration effectively at two times. Recurrence of nitrite accumulation occurred at low DO concentration（≤0. 7mg·l^-1 ） . The more completely disappearance of nitrite accumulation, the much time was cost to recur it. Low DO was not always bring out severe sludge bulking, because the ammonia oxidized bacteria used the limited DO sufficiently and predominated in wastewater for long sludge bulking period , so the sedimentation capability of sludge was good and severe did not occur. In the end DO was the key factor that affecting nitrite accumulation by analyzing other factors, i.e. pH, free ammonia（FA） concentration, temperature.