Efficient treatment of graywater using a multi-array dielectric barrier discharge plasma jet

Abstract

The increasing global demand for freshwater necessitates innovative and sustainable water treatment solutions. Graywater treatment and reuse have emerged as crucial strategies to alleviate pressure on freshwater resources. This study investigates the application of Dielectric Barrier Discharge (DBD) plasma for graywater treatment, a method less explored compared to conventional advanced oxidation processes (AOPs). The treatment involved exposing graywater to post-discharge plasma using air as the carrier gas. Plasma-generated reactive species were introduced into the water through bubbling, ensuring efficient mass transfer and enhancing contaminant degradation. Under optimal operating conditions (applied voltage: 7.6 kV, treatment time: 60 min, gas flow rate: 500 mL/min), the system achieved 90 % removal efficiency in a 30 mL reaction volume with an initial graywater concentration of 600 ppm. The results demonstrate the effectiveness of plasma-based ozonation for graywater treatment. Ionic analysis showed significant reductions in phosphate (from 38.05 ppm to 15.96 ppm) and sulfate (from 13.65 ppm to 6.23 ppm), both of which are critical components of graywater. Scavenger experiments revealed that singlet oxygen (¹O₂), hydroxyl radicals (·OH), and ozone (O₃) were the primary reactive species responsible for degradation. This study highlights the potential of non-thermal plasma technology as a sustainable and efficient solution for graywater treatment. The findings present a promising approach to addressing global freshwater scarcity through advanced plasma-based oxidation processes.