Operation optimization of A/A/O oxidation ditch for nitrogen removal from low-temperature and low-carbon municipal sewage
处理低温低碳源城市污水的A/A/O氧化沟工艺脱氮运行工况优化

Aiming to improve the efficiency of nitrogen removal from low temperature and low carbon municipal sewage,a pilot scale experimental study with A/A/O oxidation ditch process was carried out in Jingkou Waste Water Treatment Plant of Chongqing in winter.Based on experiments,the best operation mode was determined from the tested 3 modes,in which,there were 5 aeration wheels in total,with the first 3 in low-speed operation,the 4th in high-speed operation and the 5th shut-down.The best results obtained were as follows: average removal rates of COD,NH+4-N and TN were 86.5%,75.4% and 70.1% respectively and their concentrations in the effluent were 21.0,6.1 and 14.9 mg/L,respectively,which could meet the first level B class criteria specified in the Discharge Standard of Pollutants for Municipal Wastewater Treatment Plant(GB 18918-2002).Considering the first level A class criteria,compliance rates of COD,NH+4-N and TN in the effluent were 100%,20% and 40%,respectively.