Chlorine disinfection of wet weather managed flows

Blending is a practice used in the waste water industry to deal with wet weather events where the hydraulic capacity of the treatment facility could be compromised. Blending consists of influent bypassing secondary treatment and then recombining or “blending” with disinfected secondary effluents before discharge into the receiving waters. Bench scale blending experiments were performed in this study with different ratios of primary to secondary waste water (5:5, 3:7, and 1:9). Blended effluents were disinfected at two concentrations and evaluated for microbiological indicators. Results indicate that disinfection of blended waste water is sufficient to reduce indicators such as fecal coliforms, however phages are more resistant and persist in samples with higher concentrations of primary effluent.