稳定塘工艺深度处理污水厂二级出水的研究

采用CAST/稳定塘组合工艺以实现城镇污水处理的功能提升。分析了该组合工艺在冬、夏两季最大处理水量时的运行效果,结果表明:稳定塘系统可有效去除二级处理出水中的氮、磷和悬浮物,冬季(HRT=6.4 d)对TN、氨氮、TP、COD和SS的去除率分别为40%、70%、55%、50%、70%,夏季(HRT=5.4 d)对上述指标的去除率分别为56%、97%、76%、55%、68%,处理效果优于冬季。两种工况下稳定塘系统的出水水质均可达到《城镇污水处理厂污染物排放标准》(GB18918—2002)的一级A标准,可有效降低受纳水体的营养负荷。第一和第二单元去除了原水中大部分的污染物,其净化机理以微生物分解和物理化学作用为主,二者对去除污染物的总贡献率>70%;第三单元进水中的污染物浓度已经很低,主要作为系统出水水质的屏障。因此,CAST/稳定塘组合工艺用于提升城镇污水处理功能是可行的。

Advanced Treatment of Secondary Effluent from WWTP by Stabilization Pond Process

The combined process of CAST and stabilization pond was used to realize functional promotion of the municipal sewage treatment.The operation effect of the combined process at the maximum treatment capacity in winter and summer was analyzed.The results show that the combined process can effectively remove nitrogen,phosphorus and suspended solids from secondary effluent.In winter,the removal rates of TN,ammonia nitrogen,TP,COD and SS are 40%,70%,55%,50% and 70% at HRT of 6.4 d,and in summer,the removal rates of the above-mentioned indexes are 56%,97%,76%,55% and 68% at HRT of 5.4 d.The treatment efficiency in summer is better than that in winter.The effluent quality under two conditions can meet the first level A criteria specified in the Discharge Standard of Pollutants for Municipal Wastewater Treatment Plant(GB 18918-2002).So the combined process can effectively reduce the nutrient load of receiving water body.The first and second units remove the majority of pollutants from raw sewage with the dominant treatment mechanism of microbial decomposition and physicochemical function,and the total contribution rate to pollutant removal is more than 70%.The third unit is only used as a barrier of the system effluent quality due to very low pollutant concentration in its influent.It is concluded that the combined process of CAST and stabilization pond is feasible for promoting municipal sewage treatment function.