倒置A2/O工艺运行效果及优化控制方案

以城市污水处理厂倒置A2/O工艺为研究对象，介绍了工艺基本情况、主要工艺设计参数及技术特点。对2017—2018年污水处理厂出水的水质进行分析，结果表明:倒置A2/O工艺可有效去除COD及BOD₅，脱氮除磷功能显著。并提出了碳源投加点位、污泥外回流比及曝气池末端DO的优化控制方案。夏、秋季节，控制污泥外回流比为60%~75%、硝化液回流比为100%~150%、曝气池末端ρ（DO）为1.5~3.0 mg/L；冬、春季节控制污泥外回流比为120%~150%、硝化液回流比为200%~250%、曝气池末端ρ（DO）为3.0~5.0 mg/L，可获得较好的污染物去除效果。污水出水ρ（COD）均值为26.1 mg/L，去除率为90.4%；出水ρ（TN）均值为7.69 mg/L，去除率为78.1%；出水ρ（NH₄+-N）均值为0.445 mg/L，去除率为98.3%。通过改变除磷药剂投加点位及建设药剂自动化投加系统的方式优化除磷，实际投加量为2.5 t/d，节省了药剂费用，出水ρ（TP）均值为0.194 mg/L，去除率为96.7%。

OPERATION EFFECT AND CONTROL SCHEME OPTIMIZATION OF AN INVERTED A2/O PROCESS

Take the inverted A2/O process of the municipal sewage treatment plant as the research object, this paper introduced the basic situation, main design parameters and technical characteristics of the process, and analyzed water quality test data of the past two years. The results showed that the inverted A2/O process could effectively remove COD and BOD₅, and the function of nitrogen and phosphorus removal was notable. An optimal control scheme for the carbon source dosing point, the sludge external reflux ratio and the DO at the end of the aeration tank, was proposed. In summer and autumn, the external reflux ratio of sludge was controlled in 60%~75%, the reflux ratio of nitrifying liquid in 100%~150%, and the DO at the end of aeration tank in 1.5~3.0 mg/L. In winter and spring, the external sludge reflux ratio was controlled in 120%~150%, the nitrification liquid reflux ratio in 200%~250%, and the aeration tank end DO in 3.0~5.0 mg/L, all of which could obtain better pollutant removal effect as follows: the effluent COD average value was 26.1 mg/L, the removal rate was 90.4%, the effluent TN average value was 7.69 mg/L, the removal rate was 78.1%, the effluent ammonia nitrogen average value was 0.445 mg/L, and the removal rate was 98.3%.Phosphorus removal was achieved by changing the addition point of phosphorus removal agents and building an automated chemical dosing system. Then the actual dosage of the phosphorus removal agent was reduced obviously to 2.5 t/d, and the TP average of the effluent was 0.194 mg/L, with a removal rate of 96.7%.