Effects of Advanced Oxidation on Wastewater Effluent Ecotoxicity: A Novel Assessment through the Life History and Lipidomics Analysis of Daphnia magna

Advanced oxidation processes (AOPs) generate reactive radicals to effectively degrade pharmaceuticals and personal care products (PPCPs) in wastewater that are not removed during conventional biological treatment. However, transformation products from AOPs may still be biologically active and have deleterious effects on aquatic organisms. This study is based on an integrated approach using targeted PPCP analysis, Daphnia survivability and life history, and high-resolution mass spectrometry-based targeted lipidomics analysis to assess the performance of a novel AOP ultraviolet/peracetic acid (UV/PAA) and conventional UV/hydrogen peroxide (UV/H₂O₂). Both AOP treatments significantly decreased PPCP concentrations compared to the secondary activated sludge treatment alone. Daphnia survivability tests showed no significant differences between the control group and the treated group exposed over 5 days to AOP-treated wastewater. In contrast, a 14 day life history assessment and associated lipidomics showed that while 6 mg/L UV/H₂O₂ or UV/PAA treatment decreased wastewater toxicity to an overall level that is comparable with the control, the 3 mg/L UV/PAA AOP treatment did not achieve the same decrease in toxicity. At the latter condition, Daphnia exhibited smaller growth, significant changes in lipids, and lower rate of population increase than the control. The use of integrated methods allowed for the elucidation of sub-lethal effects of AOP-treated wastewater on Daphnia.