Use of plasma gliding arc discharges on the inactivation of E. Coli in water

The objective of the present study was to investigate the feasibility of using a gliding arc (GA) discharge to inactivate microorganisms in water. Microbubble generators were utilized to uniformly disperse gas bubbles that contain H₂O₂ in water. In addition, the residual effect of H₂O₂ in plasma-treated water was assessed by continuous quantitative measurement of microbiological colony forming units (cfu) in water after the completion of GA discharge. Application of the GA plasma discharge to water decreased pH from 6.15 to 3.55 after 25-min treatment, and the lowered pH was maintained for 4 h after treatment ceased. The present study showed a total 6-log reduction in the cfu counts of Escherichia Coli with plasma treatment of 25 min duration: 4-log reduction from 10⁶ to 10² during treatment and an additional 2-log reduction from 10² to 10 ⁰ during the 2 h after treatment. The use of microbubble generators significantly enhanced the benefit of H₂O₂ in acidic water, increasing the bacterial inactivation ability of the plasma treatment with GA discharge.