Abstract:

The design capacity of the third-stage project of Daoyi WWTP in Shenyang city is 5.0×10⁴ m³/d and the design effluent quality meets the first level A criteria specified in the Discharge Standard of Pollutants for Municipal Wastewater Treatment Plant（GB 18918—2002）. Due to the fact that drainage system in service area of WWTP was dominated by the combined drainage system in the current situation，the inlet water quality and quantity fluctuated greatly. Based on the analysis of the process，water quality characteristics and operation of the existing WWTP，the design adopted multi-mode A²/O+high-density sedimentation tank+continuous sand filter. The multi-mode A²/O process was able to deal with fluctuant of inflow quality and improve the removal efficiency of nitrogen and phosphorus because it could realize flexible conversion of multiple operation modes. High-density sedimentation tank and continuous sand filter were built for further removal of TP and SS，and the final effluent was disinfected by sodium hypochlorite. The engineering operation results showed that the design process met the design effluent standard and had good adaptability to the impact of water quality. The annual mean values of effluent COD，NH₃-N，TN，TP，and SS were 25.0，1.16，8.72，0.23，and 5.41 mg/L respectively. The total investment of the project was 126 million yuan，and the treatment cost was 0.875 yuan/m³.

Key words: multi-mode A²/O process, wastewater treatment plant, nitrogen and phosphorus removal

摘要：

沈阳市道义污水处理厂三期工程设计规模为5.0×10⁴ m³/d，设计出水水质执行《城镇污水处理厂污染物排放标准》（GB 18918—2002）一级A标准。由于污水处理厂服务范围内的排水系统现状以合流制为主，该项目进水水质、水量波动较大。在分析现有污水处理厂工艺、水质特点及运行情况的基础上，设计采用预处理+多模式A²/O+高密度沉淀池+连续流砂过滤工艺。多模式A²/O工艺能够实现多种运行方式的灵活切换，以应对水质波动并提升脱氮除磷效果。“高密度沉淀池+连续流砂过滤”工艺进一步去除总磷和悬浮物，尾水采用次氯酸钠进行消毒。工程运行结果显示：设计工艺能够达到设计出水标准，并且对水质冲击负荷具有良好的适应能力。COD、NH₃-N、TN、TP、SS的年平均出水质量浓度分别为25.0、1.16、8.72、0.23、5.41 mg/L。工程总投资为1.26亿元，处理成本为0.875元/m³。

关键词: 多模式A²/O工艺, 污水处理厂, 脱氮除磷

CLC Number: 

• X703