Source water quality effects on monochloramine inactivation of adenovirus, coxsackievirus, echovirus, and murine norovirus

There is a need for more information regarding monochloramine disinfection efficacy for viruses in water. In this study, monochloramine disinfection efficacy was investigated for coxsackievirus B5 (CVB5), echovirus 11 (E11), murine norovirus (MNV), and human adenovirus 2 (HAdV2) in one untreated ground water and two partially treated surface waters. Duplicate disinfection experiments were completed at pH 7 and 8 in source water at concentrations of 1 and 3 mg/L monochloramine at 5 and 15 °C. The Efficiency Factor Hom (EFH) model was used to calculate CT values (mg-min/L) required to achieve 2-, 3-, and 4-log10 reductions in viral titers. In all water types, monochloramine disinfection was most effective for MNV, with 3-log10 CT values at 5 °C ranging from 27 to 110. Monochloramine disinfection was least effective for HAdV2 and E11, depending on water type, with 3-log10 CT values at 5 °C ranging from 1200 to 3300 and 810 to 2300, respectively. Overall, disinfection proceeded faster at 15 °C and pH 7 for all water types. Inactivation of the study viruses was significantly different between water types, but there was no indication that overall disinfection efficacy was enhanced or inhibited in any one water type. CT values for HAdV2 in two types of source water exceeded federal CT value recommendations in the US. The results of this study demonstrate that water quality impacts the inactivation of viruses and should be considered when developing chloramination plans.

Research highlights
► We investigated monochloramine disinfection efficacy on viruses in source waters.
► Disinfection was most effective for murine norovirus, followed by coxsackievirus B5.
► Disinfection was least effective for adenovirus 2 and echovirus 11.
► Disinfection efficacy was significantly different between source water types.
► Water quality plays an important role in monochloramine disinfection of viruses.