A/O生物脱氮工艺处理生活污水中试(一)短程硝化反硝化的研究

A/O pilot-scale nitrogen removal process treating domestic wastewater Ⅰ. The study of short-cut nitrification and denitrification

应用A/O生物脱氮中试试验装置处理实际生活污水,从pH、污泥浓度（MLSS）、自由氨（FA）、温度、污泥龄（SRT）、溶解氧（DO）和水力停留时间（HRT）等方面系统的分析了A/O工艺实现短程硝化反硝化的主要影响因素.结果表明,DO浓度是A/O工艺实现短程硝化反硝化的主要因素,由FISH检测发现长期控制低DO浓度（0.3～0.7 mg·L^-1）可以导致亚硝酸盐氧化菌（NOB）的淘洗,从而实现稳定的亚硝酸盐积累率,试验获得平均亚硝酸氮积累率为85%,有时甚至超过95%.提高DO浓度,1周内亚硝酸氮积累率从85%降到10%,继续维持低DO浓度,大约需要2个污泥龄时间才可重新恢复到较高的亚硝酸氮积累率（＞75%）.低DO浓度下,试验初期污泥沉淀性能随着亚硝酸氮积累率的增加而变差,而在试验后期,无论亚硝酸氮积累率多高,污泥沉淀性能一直很好,SVI值处于80～120 mL·g^-1。

The effect of main factors, such as pH, MLSS, FA, T, SRT, DO and HRT, on short-cut nitrification and denitrification was systematically analyzed in a pilot-scale A/O nitrogen removal plant treating domestic wastewater. The experimental results demonstrated that DO is the main factor to achieve short-cut nitrification in the study. Fish analysis presented that a long-term operation at low DO （0.3 ～0. 7mg·L^-1 ） concentration lead to the elimination of ammonia oxidizing bacteria （AOB）, so as to realize nitrite accumulation. The average nitrite accumulation ratio could reach 85%; sometimes the nitrite accumulation ratio was higher than 95%. The short-cut nitrification and denitrification was damaged with the nitrite accumulation ratio decreasing from 85% to 10% when DO was increased above 1.5 mg·L^-1. The nitrite accumulation ratio was resumed to 75% after about two sludge ages with the DO kept in low level. The SVI increased with the increase of nitrite accumulation ratio in the initial period, but the SVI maintained at a proper level of 80～120mL·g^-1 in the after time no matter how high or low the nitrite accumulation ratio was.