CAST工艺处理低C/N废水中DO对NO2-积累的影响

研究了有效容积为72 L的循环式活性污泥法反应器在不同溶解氧浓度下,处理低碳氮比生活污水时,去除氨氮过程中亚硝酸盐积累的情况.选取5个DO浓度水平进行试验,结果表明,在低DO浓度下有效去除氨氮的同时,实现了长期稳定的亚硝酸盐积累,并且无污泥膨胀发生,当DO在0.5 mg/L时,系统内亚硝化率(NO2-/NOx-)可达80%以上,氨氮去除率＞90%,SVI在109 mL/g左右;当DO＜0.5 mg/L时,氨氮去除率下降;当DO＞1 mg/L时,硝化反应较彻底,但硝化过程向全程硝化转化.

Influence of dissolved oxygen on the nitrite accumulation in the CAST reactor for treating low C/N wastewater

Biological nitrogen removal via nitrite pathway in wastewater treatment is of great benefit to saving the cost of aeration and organic carbon source for denitrification. A cyclic activated sludge technology reactor was operated in nitrification mode, feeding domestic wastewater with low C/N ratio. The influence of DO was studied, changing the DO concentration from 0. 3 to 4. 0 mg/L. Setting a DO concentration of 0. 5 mg/L in the main aerated zone of the reactor, it was possible to achieve a nitrite ratio (NO2-/NOx-) more than 80% with a mean ammonia removal rate over 90% and a SVI of 109 mL/g. When the DO concentration was above 0. 5 mg/L, the nitrite ratio decreased. While the DO concentration was below 0.5 mg/L, the ammonia removal became lower. From the experimental results, it is concluded that a CAST (cyclic activated sludge technology) reactor with DO control is feasible to achieving stable partial nitrification for treating domestic wastewater with low C/N ratio.