Test And Study On PRB Technique Treating Polluted Groundwater

In the test the coarse sand, the zero valent iron (ZVI), the soil with rich microbes, the sawdust are mixed evenly by different volume proportions and put into the permeable reactive barrier (PRB) reactors respectively as the filling stuff, the leachate generated in Datong landfill is diluted 5 times and 40 times to be as the simulated polluted groundwater and the objects of the study, and 2 groups of orthogonal experiments aere carried out to analyze the removal effect of these PRB reactors by contrast. Conclusions can be drawn through the analysis of the reactors'outwater quality that the pH values of the outwaters go higher but no more different when the pollutant concentration of the inwater increases, the CODCr removal rates of the same PRB reactor vary intensively when the inwater pollutant concentration changes, and half of the all reactors'outwater CODCr values get higher in the lower-inwater-pollutant-concentration orthogonal experiments, but the highest outwater CODCr removal rates surpass 50% in both of the 2 groups of orthogonal experiments, the BOD5 removal is similar to the CODCr removal, in the 1st group of orthogonal experiments the 9th reactor's BOD5 removal rate is up to93%, but in the 2nd group of orthogonal experiments most of the outwater BOD5 values rise up and the highest BOD5 removal rate is 56% which belongs to the 5th reactor, the turbidity removal rates keep in a higher level and many of them are between 80% and 90% in both of the 2 group of orthogonal experiments, the chroma removal effect with a lower inwater pollutant concentration is generally better than the one with a higher inwater pollutant concentration, the chroma removal rates of 4th, 5th, 10th and 16th reactors are over 70% in both of the 2 group of orthogonal experiments. Therefore, it is feasible to treat the groundwater contaminated by leachates with PRB techniques. According to the intuitionistic analysis about the orthogonal experimental results, it can be found that the calculated optimal factor level changes as the inwater pollutant concentration or the evaluation index varies, with the integrated evaluation index the optimal media proportions are 20% of the 100-eye iron powder and 20% of the sawdust, the best residential time is 5 days in the 1st group of orthogonal experiments, correspondingly 20% of the 100-eye iron powder and no sawdust, 2 days in the 2nd group of orthogonal experiments. It can also be found by analyzing the experimental results that the inwater quality, materials and proportions of the reactive media in the PRB reactor, the residential time are the factors which have effects on the treatment of the polluted groundwater by PRB techniques. At last, a PRB iss designed to deal with the groundwater pollution by leachates according to the current conditions of the groundwater pollution in Datong landfill, which provided a solution for the groundwater protection and treatment of this area.