Efficacy of Cold Atmospheric Plasma Treatment on Chemical and Microbial Pollutants in Water

Here, we studied the effect of cold atmospheric plasma (CAP) on chemical and microbial pollutants. A model compound for organic water pollutants, crystal violet dye (CV), was used as a chemical probe to monitor a rapid change in the reactive oxygen and nitrogen species (ROS/RNS) in water. We used a point electrode to generate plasma above the treated liquid. Three variables (the gap distance between the point electrode and the water surface, the input voltage, and the water thickness below the point electrode) have been studied to show their effects on CV percent removal as a response. Additionally, the microbicidal effect of CAP against rotavirus (RoV), φX174, E. coli, and S. aureus in water was investigated. A rapid virucidal activity was observed, up to 5 log10 reduction in 1 min for φX174 and 4.3 log10 reduction of RoV in 5 min CAP exposure. Viral removal could be due to the fact that plasma produced active species which have an oxidative effect on viral capsid protein. As expected, bacteria were more sensitive to CAP than viruses, as ∼4log10 removal was observed after 30s exposure. The potent antibacterial effect of CAP could be due to the reaction of free radicals with the outer membrane of bacteria or even the penetration of the bacterial cells. CAP has the potential to control microbial and chemical pollution in water. However, further work should be conducted to determine the efficacy of CAP treatment in complex water matrices. The effect of voltage, gap distance and water thickness on the performance of cold atmospheric plasma (CAP) was optimized by response surface method. More than 95% reduction of crystal violet was obtained in 20 min exposure to CAP. A potent virucidal effect on RNA/DNA viral models was observed. Also, CAP treatment for 30 s was enough for 4log10 removal of bacteria. Thus, CAP has the potential to control pathogens and remove chemical pollution in water.