Investigation of the Effect of Plasma Discharge on Harmful Microorganisms in Water

Microbiological contamination of drinking water remains a significant public health concern worldwide, necessitating the development of efficient and environmentally friendly disinfection technologies. This study investigated the effectiveness and physicochemical mechanisms of water treatment using high-frequency electrical discharge plasma. Experimental research was conducted employing a laboratory dielectric barrier discharge reactor operating at 10–30 kHz and 10–25 kV, with treatment durations ranging from 5 to 20 min. Plasma exposure resulted in pronounced physicochemical changes in the aqueous medium, including a decrease in pH from 7.1–7.3 to 5.4–6.0 and an increase in electrical conductivity from 280–340 µS/cm to 480–620 µS/cm. The formation of reactive oxygen species, including hydroxyl radicals, ozone, and hydrogen peroxide, was confirmed, with hydrogen peroxide concentrations varying between 0.35 and 1.20 mg/L. Microbiological analysis demonstrated a reduction in microbial concentration from approximately 105–106 CFU/mL to 102–103 CFU/mL, corresponding to 3–4 log inactivation. The results indicated that microbial reduction was strongly associated with the generation of reactive species and treatment duration. Energy density within the range of 0.3–1.2 kWh/m3 was found to support effective disinfection performance. The findings demonstrated that high-frequency plasma treatment established a strong oxidative environment leading to microbial membrane disruption and cellular damage. Overall, the study confirmed the potential of high-frequency electrical discharge plasma technology as a promising approach for drinking water disinfection and provided a basis for further optimization and scale-up investigations.