低溶解氧对改良A／A／O工艺脱氮除磷的影晌

以采用厌氧／缺氧／好氧（A／A／O）工艺的城镇污水处理厂为研究对象，利用改良A／A／O中试装置开展处理实际污水的研究，通过与实际工艺的运行效果对比，系统探讨了低溶解氧（DO）浓度以及好氧池末端非曝气区的设置对脱氮除磷的影响。结果表明当好氧区的DO平均浓度从2．2mg／L逐渐降至1．0mg／L时，系统COD的去除效率与硝化效果未受到影响，但除磷效果明显下降；随着DO平均浓度的降低以及非曝气区对DO的缓冲，保证了缺氧区的缺氧环境，同时有效降低了内回流液中DO浓度的携带对碳源的消耗，提高了反硝化效率，使得系统对TN的去除率逐渐升高。就总体运行情况来看，A／A／O工艺中好氧区DO的平均浓度可以在1．0—2．0mg／L之间运行，同时在好氧区末端设置非曝气区，可以有效地缓冲内回流液中DO浓度对反硝化的影响，提高脱氮效率。

Effect of Low Concentration of Dissolved Oxygen on Nitrogen and Phosphorus Removal with Modified A/A/O Processes

A bench-scale reactor with modified anaerobic-anoxic-aerobic processes （A/A/O） for treating domestic wastewater was used to investigate the influences of low concentration of dissolved oxygen （DO） and the non-aeration zone at the end of aerobic tank on the nitrogen and phosphorus, comparing with the actual processes in the wastewater treatment plant. The results show that COD removal efficiency and nitrification process are basically not affected when DO decreases from 2.2 to 1 mg/L. With decrease of average DO and buffering effect of non-aeration zone, anoxic condition is guaranteed. Meanwhile, carbon sources consumed for DO in the reflux liquid can be effectively reduced. Denitrification efficiency and TN removal efficiency are increased. In summary effect of DO in reflux liquid on denitrification can be buffered and nitrogen and phosphorus removal can be improved, when average DO in aerobic zone in A/A/O process operating 1 - 2.0 mg/L and non-aeration zone at the end of aerobic zone are set.