Decomposition of trace level pollutants in industrial wastewater using underwater non-thermal plasma: toward ecotoxicity evaluation.*

Some organic pollutants are resistant to traditional wastewater treatment and are discharged into aquatic ecosystems through wastewater treatment plants (WWTPs). Secondary effluent (SE) collected from WWTPs in the pharmaceutical, electronics, and dyeing industries was treated using an underwater nonthermal plasma system. Screening analysis of trace-level pharmaceutical and pesticide substances in the range of approximately 0 ∼ 3000 ng/L in SEs has been performed and their removal Some organic pollutants resist traditional wastewater treatment and are discharged into aquatic ecosystems through wastewater treatment plants (WWTPs). Secondary effluent (SE) after WWTPs in the pharmaceutical, electronics, and dyeing industries were treated using an underwater non-thermal plasma system. Screening analysis confirmed the removal of trace-level pharmaceuticals and pesticides (0 ~ 3,000 ng/L) from SEs by the plasma system. Ecotoxicity evaluation using zebrafish showed reductions in embryotoxicity (13, 37, and 27 %) and increases in hatching rates (23.3, 20, and 10 %) after plasma treatment. Consequently, underwater non-thermal plasma treatment is a promising method to decompose trace organic pollutants and reduce SE's biological effects, enhancing the safety of aquatic ecosystems. plasma treatment was verified. The ecotoxicity evaluation of the SE samples using zebrafish showed a reduction in embryotoxicity (13 %, 37 %, and 27 %) and an increase in hatching rate (23.3 %, 20 %, and 10 %) after the plasma treatment. Therefore, underwater nonthermal plasma treatment is prospected as an appropriate option to ensure the safety of the aquatic ecosystem as it can effectively reduce trace organic pollutants and mitigate their biological effects.