采用GC-MS法分析城市污水处理系统对PCBs的去除效果

Research on the removal efficiency of PCBs in municipal sewage treatment system by GC-MS

分别采用固相萃取法和索氏提取法对城市污水处理厂中各处理工艺段的出水和污泥样品进行预处理,经净化分离出样品中的PCBs,再经GC-MS法对其进行定性和定量分析。分析结果表明:进水中7种PCBs均存在,总含量为25.25 ng.L-1;初级沉淀后的出水中PCBs总量降至15.56 ng.L-1;二级处理出水中检测出PCBs总含量为11.81 ng.L-1,深度处理出水中PCBs总浓度在4.97 ng.L-1。好氧污泥中PCBs总量较厌氧污泥中多。污水中各PCBs单体的去除率同LogKow具有良好的线性关系,证明了在污水处理系统中PCBs主要通过吸附作用转移到污泥或颗粒物上而得到去除。

Solid phase extraction （SPE） and soxhlet extraction （SE） were adopted respectively in the enriching of PCBs in effluent samples of the different treatment stages and in sludge samples from A/O sludge systems in Harbin Sewage Treatment Plant, and the extracts were further purified, separated and concentrated, and seven specified PCBs congeners in the condensate were identified and quantified by GC -MS procedure. The analysis results indicated that all the seven PCBs congeners occurred in the influents sample, and the total concentration was 25.25 ng·L^-1 ; the total concentration of the PCBs congeners decreased to 15.56 ng·L^-1 after primary sedimentation; the total concentration of those PCBs congeners was 11.81 ng·L^-1 in the effluent sample of the secondary treatment stage, and their total concentration was 6.78 ng·L^-1 in the effluent samples of advanced treatment stage. Concentration of specified PCBs in aerobic sludge was higher than that in anaerobic sludge. A good linear relation between removal efficiency and LogKow suggested that compounds with a strong hydrophobic character are principally removed through sorption to sludge or particles.