Change of Genotoxicity of Simulated Textile Dyeing Wastewater during Anoxic-aerobic Treatment

The pollution of textile dyeing wastewater is of highly concern for its notorious biotoxicity, especially the genotoxicity, which can cause DNA damage and chromosome aberration to aquatic flora and fauna. In this study, a lab-scale reactor system was constructed to study the change of genotoxicity during the anoxic-aerobic treatment of simulated textile dyeing wastewater. The genotoxicity of wastewater samples were evaluated by SOS/umu test. The results revealed that the genotoxicity significantly increased by anoxic treatment, and could not be completely eliminated after aerobic treatment. By fractionating dissolved organic matters (DOM) in wastewater into different fractions, it was found that hydrophobic acids (HOA) and the hydrophobic neutrals (HON) were the key fraction with genotoxic activity. By comparing the genotoxic equivalent of the samples and their corresponding dissolved organic carbon (DOC) value, it was found that the aerobic effluent had higher genotoxic intensity than original influent based on DOC.