Bioremediation Of PCBs Contaminated Soil Using Wetland Plants And Land Farming

PCBs(polychlorinated biphenyls) are a kind of synthetic compounds that remain in the environment because of its semi-volatile-characteristics. It poses a serious threat to ecological environment and human health. Soil and sediment are the main destination of polychlorinated biphenyls. Nowadays, remediation technologies of polychlorinated biphenyls are based mainly on physical and chemical methods. However, these methods are expensive and easily destroy soil structure. Bioremediation, such as phytoremediation and land farming are gradually becoming the center of research due to their environment friendly features.In this paper, we explored remediation efficiency of polychlorinated using the wetland plants-land farming method in indoor simulation-wild district-poilt scale testation with land farming. The main results obtained are as follows:(1) Laboratory simulation experiment of wetland plants remediation: polychlorinated biphenyls could be dechlorinated and degraded effectively using Acorus tatarinowii Schott and Iris pseudacorus.The initial concentration of PCBs was123.3ng/g and126.0ng/g. The total amount of PCBs decreased by27.2%and16.1%after60days’ treatment. The degradation efficiency of high chlorinated biphenyls were23.4%and20.2%. Meanwhile, low chlorinated biphenyls had29.7%and13.2%. Arundo donax var. versicolor and cyperus alternifolius were the second with, only6.5%and3.4%respectively. Compared to flooding treatment, the changes were small in high chlorinated biphenyls. However, the low chlorinated biphenyls degraded by10.1%and8.0%. There were no significant difference between canna indica and control. Besides, wetland plants could absorb PCBs, but only0.035%～0.238%.(2) Laboratory simulation experiment of land farming: the initial concentration of PCBs was583.2ng/g, the total amount of PCBs decreased by18.0%after90days’ remediation,0.6%of high chlorinated biphenyls and29.9%of low chlorinated biphenyls.(3) Field plot experiment:the initial concentration of PCBs was127.7ng/g. The total amount of PCBs decreased by6.0%using wetland plant after90days’ remediation. The high and low chlorinated biphenyls degraded by12.1%and0.5%. The initial concentration of PCBs was66.9ng/g under land farming. The total amount of PCBs decreased by16.0%,31.7%of low chlorinated biphenyls. However, the concentration of high chlorinated nearly had no change. The initial concentration of PCBs was68.9ng/g under wetland plant-land farming. The combined remediation efficiency of PCBs was28.3%after180days’ treatment. There was degradation efficiency of20.3%using wetland plant and46.1%using land farming.(4) The pilot experiment of wetland plant-land farming:the initial concentration of PCBs was320.8ng/g～402.5ng/g. The total amount of PCBs decreased by38.2%after180days’ combined remediation. There was degradation efficiency of11.8%using wetland plant and26.4%using land farming.The above results of indoor simulation, field plot and pilot experiment showed that the combined method of wetland plants and land farming effectively improved dechlorination and degradation of PCBs. This method had a wide application prospect.