| With the undergoing of rapid urbanization,industrialization and extensive agricultural development,the shortage of drinking water resources and the deterioration of water quality are becoming more and more serious in China.Various studies have shown that a variety of pollutants in drinking water had the effect of teratogenicity,carcinogenicity,mutagenicity.Although the dose is very low,there are still potential toxic effects of chronic exposure in drinking water.Environmental pollution leads to increase burden of disease and high incidence of cancer.But presently,the method of drinking water safety assessment was mainly through physical and chemical detection,which cannot reflect all pollutants and toxic effects in the water.Many studies have already tried to use bioassay as water quality evaluation index,but the toxic effect and test methods were single,and the researches were relatively fragmented.A battery of bioassays including acute toxicity,genetic toxicity and AHR effects and a comprehensive evaluation system were established to evaluate the quality of drinking water in this study.And it was applied to the evaluation of drinking water plant advanced water demonstration project and disinfection effluent of two different processes of drinking water plant in Yancheng.1.A battery of bioassays was established to evaluate toxic effects of drinking waterA battery of bioassays including acute toxicity,genetic toxicity and AHR effects,with the CCK8 test,Ames test(TA98,TA100),comet assay and micronucleus test in human peripheral blood EROD test.The positive control was used to check the effectiveness and accuracy of each experiment.A set of evaluation system for drinking water quality was constructed by water quality classification and analytic hierarchy process.According to the 5 index variables and 3 indicators to design the expert consultation survey,and then,10 experts with rich experience were chosen to be consulted on the importance of each index in the form of scoring table.The 9-scale method was used to structure comparison matrix after comparing every two indexes,if consistency of expert opinion within the standard range,the weight coefficient of each index is calculated.The results of this study showed the consistency ratio and CR value of the judgment matrixes were less than 0.1,which indicated that the expert opinions were in good agreement.According to the calculation of the index weight coefficient matrix,three main level indicators,acute toxicity,genetic toxicity index,AHR effect weight coefficients were 0.1,0.5 and 0.4,the weight coefficient Ames test,micronucleus test and comet assay in human peripheral blood lymphocytes were 0.357,0.357 and 0.286.2.Biological toxicity effect of advanced treatment of drinking water.The established method of biological toxicity assessment of drinking water was applied to advanced water demonstration project of a drinking water plant in Yancheng.A total of four water samples were collected from raw water,sand,filtered water,BAC water and tap water,representing raw water,conventional treatment effluent,advanced treatment effluent and tap water in the process of drinking water treatment.The sampling volume of each water sample is 100 liters.XAD-2 resin was used to enrich the water sample,after elution and concentration,it was applied to biological toxicity test.The results showed that MRTA98 and MRTA100 were less than 2 under the condition of with and without S9,and no positive results were found in Ames strain.And the results of peripheral blood lymphocytes revealed that the raw water,sand filtered water and tap water all showed strong mutagenicity.At the minimum dose of 0.125L/hole,the micronucleus rate were 11.40± 1.98,10.52 ±0.88 and 9.13 ±0.47,which were significantly higher than that of the control group(p<0.05).And the pollution index was greater than or equal to 1.5,showing slight pollution.However,the positive results were not detected in the effluent after BAC treatment.Comet assay displayed that four water samples showed cell tailing at different concentrations,and the percentage of tail DNA,tail length and tail distance showed significant difference at different concentrations(p<0.05).The results of cell proliferation toxicity test showed that the concentration of water concentrate in raw water and sand filtered water decreased with the increase of concentration.The raw water appeared*at three time points,the cell viability decreased by 100ml/ml,100ml/ml and 50ml/ml,respectively,and the cytotoxicity of sand filtered water was slightly decreased compared with that of raw water,but it still had high cytotoxicity.However,the water samples of BAC water and tap water showed a certain extent to promote the proliferation of cells.BAC water appeared the cell viability increased by 200ml/ml,100ml/ml and 100ml/ml,tap water appeared the cell viability increased by 50ml/ml,100ml/ml and 100ml/ml(p<0.05).The results of EROD enzyme activity test showed that the TCDD-TEQ numbers of raw water,sand filtered water,BAC water and tap water were 9.39pg/L,10.65 pg/L,1.98 pg/L and 3.91 pg/L.We integrated the genetic toxicity of water quality,acute toxicity,and aromatic hydrocarbon receptor effects.The order of the comprehensive toxicity drinking water quality index(DWQI)was:sand filtration water>raw water>tap water>BAC water.The scores of acute toxicity and aromatic receptor effect were:raw water = sand filtration water>BAC water = tap water.In terms of genotoxicity,the scores of DWQI was the tap water = sand filtration water>raw water>BAC water.3 Comparison of biological toxicity effects of different drinking water treatment processesWe simulated the traditional process of disinfection effluent and advanced treatment of disinfection effluent by small scale equipment,and compared group biological toxicity test to disinfection effluent of two different processes.It was found that the genotoxicity,acute cytotoxicity and aromatic receptor effects of the different genetic end points of the traditional disinfection effluent were significantly higher than those of the advanced treatment.In the Ames test,positive results appeared within the dose range of the 2L/dish,in the high dose group,the MRTA98 in the non-activation system was 2.34,and the MRTA100 was 3.40.Both showed dose response relationship and could be positive for mutagenicity.In the traditional process,the effluent MR is also greater than 2 at the dose of 1L/dishes,suggesting that the major mutagens in water samples are base substitution mutants,such as chloroform.For the two processes,the genotoxicity of disinfection effluent,micronucleus and comet assay were consistent with that of Ames.The micronucleus rate of disinfection effluent produced by the traditional process in micronucleus test was significantly higher than in the advanced treatment effluent.The percentage of tail DNA,tail length and tail distance of the comet test show that the pollutants in the effluent of the traditional process produce DNA damage effect,which is higher than those in the advanced treatment process.Results from the acute cytotoxicity test showed that the traditional process of disinfection of effluent after the cells with strong toxic effects in high dose group,the proliferation of disinfected water depth treatment appears,that may exist in water environmental endocrine disruptors.While the aromatic receptor effect,the advanced treatment process,disinfection effluent is lower than the traditional process.From the comprehensive scoring index,the advanced treatment can effectively reduce the toxic effect of traditional drinking water treatment process.4 Conclusion:(1)A battery of bioassays including acute toxicity,genetic toxicity and AHR effects were established,the accuracy of each test was checked by the positive control.A set of integrated evaluation system for drinking water quality was constructed by water quality classification and analytic hierarchy process.(2)A new integrated bioassays and evaluation system were applied to the detection of the biological toxicity of effluent from different units in a drinking water treatment demonstration project of a plant in YanCheng.According to the result of integrated evaluation system,it is concluded that the exposure of aromatic hydrocarbons may be related to the acute toxicity of water quality,and the genetic toxicity factors of sand filter water may also be related to polycyclic aromatic hydrocarbons.O3-BAC could be used to remove toxic pollutants in water.But after chlorination,genotoxicity increased significantly,which could be caused by disinfection by-products(3)Traditional technology and advanced treatment were simulated to compare biological toxicity of different disinfection effluent treatment process,whether it is found that the traditional disinfection water disinfection water was higher than that of advanced treatment process in comprehensive toxicity effect and inner layer,it indicated that advanced treatment process could reduce the toxic effects of traditional technology.(4)Compared with O3-BAC advanced treatment technology and traditional technology,can reduce the toxicity of water effect,but in layer index analysis found that the advanced treatment process of disinfection effluent still has certain genetic toxicity,for the micro polluted source water,tap water to remove disinfection by-products,still need to Improve the treatment process. |
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