Toxicity changes of wastewater during various advanced oxidation processes treatment: An overview

Abstract

Advanced oxidation processes (AOPs) have been widely applied for the advanced treatment of recalcitrant wastewater. However, the toxicity changes during AOPs are still unclear because in some cases the intermediate products could exhibit equivalent or even higher toxicity compared with the original pollutants. Therefore it is necessary to evaluate the toxicity evolution during AOPs. This review mainly focused on the toxicity changes of wastewater during various AOPs treatment, including Fenton/Fenton-like oxidation, ozonation/catalytic ozonation, persulfate radical-based oxidation, photocatalytic oxidation, ionizing radiation, electro-catalytic oxidation, ultrasound oxidation and wet oxidation. Firstly, the toxicity assessment methods were summarized, including acute toxicity (such as luminescent bacteria assay, fish assay, water flea assay and algae assay), genetic toxicity (Ames assay, SOS/umu assay, comet assay and micronucleus assay), estrogenic activity, immunity toxicity, and endocrine disrupting effect (such as yeast two-hybrid assay and fish endocrine disrupting assay), the applications of these methods in determining the toxicity changes of wastewater during AOPs treatment were summarized and analyzed in detail. Secondly, the toxicity prediction by computational simulation was introduced, mainly focusing on two common software, including TEST and ECOSAR. Thirdly, the strategies for eliminating the toxicity of wastewater after AOPs treatment were proposed. Finally, the concluding remarks and perspectives were presented for further study. This review will deepen to understand the toxicity evolution of wastewater during AOPs.