The effect of low-temperature plasma on microorganisms in water and wastewater

The presence of microorganisms in water and wastewater is of significant importance for public health. Bacteria from the Enterobacteriaceae family, such as E. coli and Salmonella sp., pose a serious health risk. Their presence in treated wastewater and drinking water is absolutely unacceptable. The aim of the study was to evaluate the effectiveness of the bactericidal properties of low-temperature atmospheric plasma. The research involved treating water and wastewater samples containing suspended bacteria with plasma for varying durations(ranging from 5 seconds to 30 minutes). The plasma stream was generated using a pulsed atmospheric plasma arc, with air as the working gas. The samples contained both microorganisms that naturally occur in wastewater treatment plants and laboratory-cultured strains (in water). The results showed that low-temperature atmospheric plasma effectively eliminates microorganisms, although the required exposure time depends on microbial origin. Laboratory-cultured bacteria were eliminated within 30 seconds of plasma treatment, whereas naturally occurring wastewater microorganisms required up to 20 minutes for effective inactivation. The efficiency of the process depended on many factors such as contact time and microorganism type . In addition to its strong bactericidal and fungicidal properties, low-temperature atmospheric plasma also impacts physicochemical parameters , including pH and electrical conductivity. However, these changes tend to stabilize within 24 hours, particularly in wastewater samples. Overall, cold plasma presents a promising method for water and wastewater disinfection.