Effects of chemical agent injections on genotoxicity of wastewater in a microfiltration-reverse osmosis membrane process for wastewater reuse
•Wastewater genotoxicity of MF-RO process for municipal water reuse was detected.•Genotoxicity per unit DOC of RO concentrate was higher than that of RO influent.•Kathon biocide widely used in RO system was highly genotoxic in vitro.•Kathon biocide retained in RO system could increase genotoxicity o...
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Veröffentlicht in: | Journal of hazardous materials 2013-09, Vol.260, p.231-237 |
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Sprache: | eng |
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Zusammenfassung: | •Wastewater genotoxicity of MF-RO process for municipal water reuse was detected.•Genotoxicity per unit DOC of RO concentrate was higher than that of RO influent.•Kathon biocide widely used in RO system was highly genotoxic in vitro.•Kathon biocide retained in RO system could increase genotoxicity of RO concentrate.•Chlorination of secondary effluent could significantly decrease the wastewater genotoxicity.
With combined microfiltration (MF)/ultrafiltration (UF) and reverse osmosis (RO) process being widely used in municipal wastewater reclamation, RO concentrate with high level genotoxicity is becoming a potential risk to water environment. In this study, wastewater genotoxicity in a MF-RO process for municipal wastewater reclamation and also the effects of chemical agent injections were evaluated by SOS/umu genotoxicity test. The genotoxicity of RO concentrate ranged 500–559μg 4-NQO (4-nitroquinoline-1-oxide)/L and 12–22μg 4-NQO/mg DOC, was much higher than that of RO influent. Further research suggested that Kathon biocide was a key chemical agent associated with the genotoxicity increase. Kathon biocide used in RO system was highly genotoxic in vitro and Kathon biocide retained in RO system could contribute to a higher genotoxicity of RO concentrate. Hence, treatments for biocides before discharging are necessary. Chlorination of secondary effluent could significantly decrease the genotoxicity and increasing chlorine dosage could be an efficacious method to decrease the genotoxicity of RO concentrate. According to the result of the experiment, the dosage of chlorine in dual-membrane process could be set to about 2.5mg Cl2/L. The effect of antiscalant (2-phosphomobutane-1,2,4-tricarboxylic acid) was also investigated; it turned out to have no effect on genotoxicity. |
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ISSN: | 0304-3894 1873-3336 |
DOI: | 10.1016/j.jhazmat.2013.05.035 |