城市污水处理厂尾水排放对水环境质量影响定量评估

THE QUANTITATIVE EVALUATION OF EFFECT ON WATER QUALITY OF URBAN SEWAGE TREATMENT PLANT DISCHARGE

定量评估污水处理厂尾水排放对水环境的影响是科学规划污水处理厂入河排污口的基础和前提。采用环境流体动力学模型EFDC对宣城市某污水处理厂排污口进行模拟预测。结果表明:在达标排放时,排污口不会对下游取水口水质产生影响。在事故排放时,90%保证率最枯月流量时污染团到达和离开下游水厂取水口的时间分别为1.7 d和3.1 d,取水口附近COD最大浓度超Ⅲ类水标准1.96倍,对下游水厂的正常运行造成严重威胁。因此排污口的设计应考虑事故排放时对下游取水口的影响。

The estimation of the effect of tail water discharge on downstream water quality is basically to the urban sewage treatment plant. This paper used the environmental fluid dynamics code( EFDC) to simulate and predict the influence of sewage draining exit of a sewage treatment plant in Xuancheng City on the downstream water quality. The results show that normal discharge has no effect on the downstream water quality. The pollutant arrived and passed by the intake for 1. 7 d and 3. 1 d respectively with the accidental discharge of 90% guaranteed rate. The maximum concentration of COD is 1. 96 times greater than the standard level of III,which is a serious threat to normal operation of water plant. Hence it is necessary to avoid the effect on downstream water plant intake during planning sewage outfall by establishing a series of accident emergency plan.