The Genotoxicity And Advanced Treatment Of The Landfill Concentrated Leachate From Nanofiltration

The landfill leachate was brown liquid which was generated during the process of landfill rubbish rot, it contained large amount of poisonous and harmful pollutants that could be highly genotoxicity, and had potential threat to the ecological environment and human health. The landfill concentrated leachate from nanofiltration did not be allowed to discharge and enter the municipal treatment, it contained higher poisonous and harmful pollutants and more harmful. So,treatment of concentrates from landfill leachate was imminent, At present, national evaluated the efficiency of concentrates treatment methods were the physical and chemsical indicators monitoring, but there was lack of genotoxicity indexes monitoring. Genetic toxicology assays could be used to detect the genotoxicity of treated concentrates based on it could reflect the pollutants in water for comprehensive toxicities. Not only assess the efficiency of concentrates treatment methods from the perspective of genotoxicity, but also can provide a new evaluating method for assessing the efficiency of concentrates treatment methods and important experimental basis. The main results of this study are as follow:The nanofiltration membrance concentrate from Xiaping, Shenzhen, China Sanitary Landfill Site were treated with UV-Fenton reagent?Fenton reagent and adsorption to activated carbon. The conventional physical and chemical parameters were measured by Multi-parameters controller, the color ? turbidity? ammonia nitrogen and COD value of concentrates were significantly reduced after the concentrates was treated by three treatment methods, UV-Fenton reagent had a better results, and the indicators of the final effluent are close to the national discharge standard. The concentration of bisphenol A(BPA) and nonlyphenol(NP) in untreated and treated concentrates were detected by using high-performance liquid chromatography-mass spectrometry(HPLC-MS), the concentration of BPA and NP were significantly reduced after three treatment methods treated, the decreased degree in the order: UV-Fenton reagent >Fenton reagent > adsorption to activated carbon. The concentration of BPA and NP in the UV-Fenton treated concentrates were under detection limits, the results showed UV-Fenton treatment method was a effective methods for degradation of BPA and NP in concentrates.Before CBMN test, the Hep G2 cytotoxicity test showed Hep G2 cells were cultured in well plates at a density of 1×105 cells/m L, cells were exposed to different concentrations of concentrates diluted in treatment medium, from 5%?10%?15%?20%?25% to 30%(v/v), cells were exposed for 24 h. The cytotoxicity assay showed that membrane concentrates contained a significant load of toxicants, and a cytotoxicity of 75% after 24 h of exposure to the highest tested concentration(30%, v/v) of untreated concentrates. After the concentrates was treated by three treatment methods, the cell viability of the final effluent was greater than 80%, and no cytotoxocity for three treatment methods treated concentrates, namely the cytotoxicity of concentrates could be significantly removed with three treatment methods. CBMN test showed increased levels of the numbers of micronucleus in cells exposed to untreated concentrates, namely untreated concentrates showed significantly chromosome damage genetic toxicity. The numbers of micronucleus were significantly reduced in cells exposed to three treatment methods, and there was no significant difference between negative control and UV-Fenton treated concentrates for micronucleus. The results showed the chromosome damage genotoxicity of concentrates was significantly reduced after three treatment methods, and UV-Fenton showed no chromosome damage genotoxicity.Comet assay(the numbers of micronucleus?DNA% in tail? tail length and olive tail moment) showed increased levels of DNA damage genotoxicity in cells exposed to untreated concentrates, compared to those occurred in cells exposed to negative control, there was a correlation between the increase in the DNA damage genotoxicity of concentrates and the increase of concentrate concentration. DNA% in tail?tail length and olive tail moment were significantly reduced in cells exposed to three treatment methods treated concentrates, the results showed the three treatment methods could significantly reduce the genotoxicity of concentrates, and the removal efficiencies decreased in the order: UV-Fenton reagent > Fenton reagent > adsorption to activated carbon. There was no significant difference between negative control and UV-Fenton treated concentrates for comet assay parameters, so UV-Fenton reagent provided toxicological safety of the treated effluent.The physicochemical parameters?CBMN test and comet assay demonstrated UV-Fenton was considerably suitable for treating such concentrates, and CBMN and comet assays were feasible tools for assessment of genotoxicity risks such concentrates.