Peracetic acid (PAA) and low-pressure ultraviolet (LP-UV) inactivation of Coxsackievirus B3 (CVB3) in municipal wastewater individually and concurrently

Domestic wastewater (WW) contains a large number of pathogenic viruses that are not significantly reduced in most WW treatment processes and are found in high numbers in the effluent of conventionally disinfected WW. In this study, secondary WW effluent bench-scale disinfection efficacy experiments with two different peracetic acid (PAA) formulations (15 and 22% peracetic acid) and low-pressure ultraviolet irradiation (LP-UV) were carried out using Coxsackievirus B3 (CVB3) as a clinically relevant surrogate for enteric viruses and Escherichia coli (E. coli) as the disinfection efficacy control. Efficacy experiments were done in a test matrix of medium-pressure UV (MP-UV) decontaminated secondary WW effluent under representative PAA doses and LP-UV fluences used at wastewater treatment plants (WWTP). Membrane filtration technique was used to determine Log₁₀ CFU reductions of E. coli and a tissue culture infectious dose 50% assay (TCID50) for Log₁₀ TCID50 reduction of CVB3. The CVB3 proved to be quite resistant to PAA with ≤1 Log₁₀ TCID50 reduction to concentrations ≤50 mg/L at a contact time of 15 min, and highly susceptible to LP-UV at 20 mJ/cm². Concurrent use of both formulations of 3 mg/L PAA with 20 mJ/cm² LP-UV achieved ∼4 Log₁₀ TCID50 reduction. The E. coli results showed ˃5 Log₁₀ CFU reductions at a contact time of 15 min with both 3 mg/L PAA formulations, 20 mJ/cm² LP-UV treatment alone, and combined with both 1.5 mg/L PAA formulations. The E. coli efficacy data were consistent with that reported in the literature and showed to be comparable to conventional chlorine disinfection. The CVB3 efficacy data has shown that PAA alone may not be suitable for the reduction of enteric viruses in secondary wastewater effluent, but this is also the case for chlorine-based disinfectants. The results from this study showed that the use of PAA with LP-UV at reasonable concentrations (1.5 mg/L) and fluence (20 mJ/cm²) can significantly reduce the PAA use and meet wastewater disinfection goals for both E. coli and CVs. However, the concurrent use of PAA with LP-UV did not lead to significant synergy in disinfection efficacy in wastewater.