PRB技术处理污染地下水的试验研究

Experimental study of PRB technique for treating polluted groundwater

试验采用粗砂、零价铁、富含微生物的土壤和锯末按不同比例搅拌均匀形成混合物，以此为介质做成可渗透反应墙（Permeable Reactive Barrier，简称PRB）反应器；取大通垃圾场产生的垃圾渗滤液，分别稀释5倍和40倍制成水样，作为模拟污染的地下水；进行2组正交试验，对各反应器的综合处理效果进行对比分析，结果表明：地下水中污染物的含量增高时，PRB出水pH值的增幅也会随之增大；进水污染物浓度变化时同一反应器CODcr去除率、BOD5去除率差异均很大，部分反应器CODcr和BOD5去除率在50％以上，但也有反应器出水CODcr和BOD5不降反升；2组正交试验的浊度去除率都处在较高的水平，许多反应器浊度去除率达到了80％～90％；进水浓度低时反应器的色度去除率超过70％。因此，用PRB处理受垃圾渗滤液污染的地下水是可行的。同时，从正交试验结果也得出了进水污染物浓度不同时PRB的最佳介质配比、反应时间以及各影响因素的丰次排序，为PRB讲一步的研究和设计提供了依据．

In the test, the coarse sand, the zero valent iron（ZVI）, the soil with rich microbes, the saw- dust are mixed evenly by different volume proportions and they are put into the permeable reactive barrier（PRB） reactors respectively as the filling stuff. The leachate generated in Datong landfill is di- luted five times and forty times respectively to simulate polluted groundwater. Two groups of orthog- onal experiments are carried out to analyze and contrast the removal effect of these PRB reactors. The results are as follows： the pH values of the outflow go higher when the pollutant concentration of the inflow increases both the CODer removal rates and the BOD5 removal rates of the same PRB reactor vary intensively when the inflow pollutant concentration changes, and some reactors＂ outflow CODcr and BOD5 removal rates surpass 50%, but there still exist many reactors whose outflow CODcr and BOD5 are higher than their inflow ones; the turbidity removal rates of the two groups keep at a higher level and many are between 80% and 90%; the chroma removal effect with a lower inflow pollutant concentration is generally better than the one with a higher inflow pollutant concentration, the chroma removal rates of some reactors are over 70%. Therefore, it is feasible to treat the groundwater contaminated by leachate with PRB technique. According to the orthogonal experimental results, the optimal proportions of the PRB reactive media, residential time and influential factors are determined, which provides a basis for further PRB research and design.