Study On Treatment Of High Concentration PCBs In Wastewater By NF-chemical Oxidation

Polychlorinated biphenyl begun to use in the1970s, and was discontinuedbecause of the cancer is due to the role of mutations teratogenic. But the pollutioncaused by the polychlorinated biphenyl problem has become the legacy ofenvironment, caught more and more attention of the domestic and foreign scholars.The characteristics of PCBs were strong toxic, chemical stability, difficult to bedegraded, and soluble in water soluble in organic. Whether entering into water or air,PCBs will be caused a lot of damage on the environment and human. Therefore, wemust pay more attention on the governance and remove of PCBs. Because of PCBscompletely insoluble in water, make a PCBs adsorption in the soil surface, difficult todeal with. To solve this problem,to contain of PCBs soil column in a large number ofsurfactant, will with PCBs in waste to, and then to deal with. At present, as theresearch on PCBs is still in its beginning stage, further research is needed.The purpose of this study was expected to remove the high polychlorinatedbiphenyl and surface active agent of wastewater, with the methods of NF andChemical oxidation. Besides, the research was also investigated, looking forward toproviding theory basis in wastewater pollution by polychlorinated biphenyl. Permeateand concentrated liquid had been separated and the effects of two main factorsincluding feeding fluid properties and operating conditions were studied by using NFprocess. The experiment using sodium dodecyl sulfate and tween80according tomass ratio1:1,and then the ratio of concentration is7g/L,then dissolve moderateconcentration polychlorinated biphenyls. Selection of optimum condition for NFprocess, which was the influent,1mg/L, concentration,50L/h, pH,9, temperature,50℃, operating pressure,0.4MPa, reflux ratio,0.7. The rejection of polychlorinatedbiphenyl, sodium dodecyl sulfate, tween80could reach93.35%,90.35%,95.37%respectively last30min by the cyclical NF process. The results showed that NF couldreject polychlorinated biphenyl, sodium dodecyl sulfate and tween80effectively, andcould provide necessary condition for removing polychlorinated biphenyl. Becausenanofiltration membrane operation after period of time can cause pollution, this paperstudies the condition of nanofiltration membrane cleaning.Choose distilled water,1% NaOH solution, and10%of citric acid solution cleaning, membrane flux for initialrecovery of flux96%. Cleaning effect is good, can continue to run.Chemical oxidation had been used to treat the concentrated liquid. The effect ofmain factors on oxidization of Fenton reagent was observed by orthogonal experiment.The optimal condition was temperature,40℃; pH,3; volume of H₂O₂,6mL;concentrate of Fe²⁺,10g/L.Comparison of Fenton reagent, ozone oxidation had been used to treat theconcentrated liquid of polychlorinated biphenyl. The optimal condition of mainfactors was pH,10; temperature,50℃; flow of O3,400L/h, in which the removal rateincreased gradually. The highest polychlorinated biphenyl removal rate could reach50.39%, the highest sodium dodecyl sulfate removal rate could reach51.07%, and thehighest tween80removal rates could reach52.37%and could stay a stabile level after10minutes with the removal rate of more than40%.Try to use light degradation process wastewater, the300W UV lamp ofwastewater was illuminate. Along with the extension of time of light, the removalrate of pollutants increases, when the response time for120min, polychlorinatedbiphenyl removal rate of30.97%; Sodium dodecyl sulfate the removal rate of33.97%;Tween the removal rate of80to33.97%. UV irradiation proof for pollutiondegradation has certain effect. This may be due to the illuminate of ultraviolet lightcaused by electronic transfer, make changes to its structure and decompositionpollutants, and lead to content decrease.In order to improve the treatment effect of polychlorinated biphenyl wastewater,UV had been used as the catalyst in the ozone oxidation process. The optimalcondition of main factors was pH,10; temperature,50℃; flow of O₃,300L/h;ultraviolet strength was300W, in which the removal rate of polychlorinated biphenyl,sodium dodecyl sulfate, tween80reach91.94%,97.78%,98.75%respectively after25minutes. The removal rate was increased obviously with the ozone oxidationprocess when the UV was the catalyst. UV and ozone oxidation in combination couldremove polychlorinated biphenyl, sodium dodecyl sulfate, tween80better than ozoneoxidation process. In this research, the method of NF-Chemical oxidation was successfully used totreat polychlorinated biphenyl of wastewater and had high removal rate by thisexperiment. It will have big engineering significance in wastewater treatment in thefuture.