Performic Acid Disinfection of Municipal Secondary Effluent Wastewater: Inactivation of Murine Norovirus, Fecal Coliforms, and Enterococci

Performic acid (PFA) is an emerging disinfectant to inactivate bacterial and viral microorganisms in wastewater. In this study, the inactivation kinetics of murine norovirus (MNV) by PFA, in phosphate buffer and municipal secondary effluent wastewater, are reported for the first time. PFA decay followed first-order kinetics and the inactivation of MNV was governed by the exposure of microorganisms to PFA, i.e., the integral of the PFA concentration over time (integral CT or ICT). The extension of the Chick-Watson model, in the ICT domain, described well the reduction of MNV by PFA, with determined ICT-based inactivation rate constants, k_d, of 1.024 ± 0.038 L/(mg·min) and 0.482 ± 0.022 L/(mg·min) in phosphate buffer and wastewater, respectively, at pH 7.2. Furthermore, the simultaneous PFA inactivation of MNV and fecal indicators indigenously present in wastewater such as fecal coliforms and enterococci showed that 1-log reduction could be achieved with ICT of 2, 1.5, and 3.5 mg·min/L, respectively. When compared with the most commonly used peracid disinfectant of municipal wastewater, peracetic acid (PAA), the ICT requirements determined using the fitted ICT-based kinetic models were ∼20 times higher for PAA than PFA, indicating a much stronger inactivation power of the PFA molecule.