Disinfection of sulfate-reducing clostridia, including Clostridium perfringens, in sewage effluents using peracetic acid

Abstract

ABSTRACT Peracetic acid (PAA) is being tested as an alternative to chlorine for sewage disinfection due to its advantages, such as the lack of disinfection byproducts produced and low impact on the discharge site ecosystem. In this study, the inactivating efficiency of PAA against Clostridium perfringens, a known chlorine-resistant microorganism that also causes numerous foodborne illnesses, was evaluated in sewage. PAA remained 80–90% after 120 min of contact with sewage, while chlorine was reduced to 3%. The inactivation curve for Escherichia coli showed a linear decrease with chlorine, while a stepwise reduction was observed with PAA. The inactivation efficacy of PAA on sulfate-reducing clostridia (SRC)-containing C. perfringens was −2.41 log at a CT value of 3,025 mg·min/L. Among the detected SRCs, the −log inactivation of C. perfringens was estimated from the percentage of cpa gene positivity, and its PAA inactivation efficacy was higher than that of SRC at −3.17 log. Although SRC contained PAA-resistant non-C. perfringens clostridia, the effectiveness of PAA for inactivating C. perfringens in the presence of organic matter indicates its effectiveness as a sewage disinfectant.