Toxicity Evaluation On Organic Extracts From Reclaimed Water Of A Wastewater Treatment Plant In Zhengzhou

ObjectiveIt has been confirmd that the reclaimed water contained different kinds andconcentration of organic pollutants, the study was to access the possible acute toxicityand genotoxicity of organic extracts from reclaimed water of a wastewater treatmentplant in Zhengzhou.MethodsThree water samples in different processing stages were collected from a sewagetreatment plant and therein organic compounds were extracted by usingthe solid-phase extraction. Vibrio qinghaiensis sp. Q67and CHO cells were exposedto the extracts with the different concentrations of1,50,100,300, and500ml/mlrespectively, and luminous intensity was measured by luminescent bacteria toxicitytest, the cytotoxicity was determined by MTT assay, the genotoxicity was evaluatedby means of cytokinesis-block micronucleus cytome assay (CBMN),comet assay andHPRT gene mutation assay, In addition, the activity of SOD and LDH and the contentof GSH were used to evaluate the effect of the extracts on the Oxidative stress systemin the CHO cells.ResultsThe results showed that the organic compounds of reclaimed water have certaingenotoxicity, the specific results are as followings:1Acute toxicity: The organic compounds have a decreased luminous intensity ina dose dependent manner, along with the increase of concentration. Contacted withthe solvent control, the inhibitions on luminescent bacteria was not obvious in low concentrations,but in100,300or500concentration multiple the effect wasstatistically significant(P＜0.05).Compared with the tertiary effluent, the secondaryeffluent have a weakening effect in the same concentration (P＜0.05).2Cytotoxicity and genotoxicity: MTT assay indicated significant decline inproliferation activity of CHO cells following the extracts exposure of100,300or500concentration multiple, and the secondary effluent was relatively safe compared withthe profound processed effluent and the effluent of the new wastewater treatingtechnique (Multi-point Strengthen Oxidation Ditch, MSOD).The percentage of tailingcells and the tail length both became greater as the concentration increased, theorganic compounds significantly increased the AU(Arbitrary units),We observed theelevated micronuclei frequency and decreased NDI of CHO cells along with theincrease of the extracts concentration. The cells exposed to three extracts with500concentration multiple and two other deep-processing extracts with300concentrationmultiple induced significant increase in the frequency of micronuclei (P <0.05), andthe decrease in NDI (P<0.05); the HPRT gene locus mutation frequency(MF)increased with the decrease of the organic extracts concentration, there are asignificant difference on HPRT gene locus mutation between the effluent of MSODtreating technique and two other profound processed effluent.3Index of oxidative stress: The content of GSH and the activity of LDH increaseand along with the increase of the extracts concentration, a little decrease at thehighest concentration, the organic extracts has a negative effect on the activity ofSOD.The activity of LDH of secondary effluent extracts was higher than two otherdeep-processing extracts, but the content of GSH and the activity of SOD have areverse results. Conclusion1The organic compounds of reclaimed water didn’t show evident acute toxicityand genotoxicity, but still had potential ecological toxicity to the environment in along-term process.2The toxicity of reclaimed water from different processing stagesand technique need further proof to verify.