Process Control for Monitoring Disinfection of Municipal Wastewater Effluent with Ozone

Municipalities in North America are typically required to achieve some level of disinfection of municipal wastewater effluent (MWWE) before discharging it to receiving water bodies. A limited number of wastewater treatment plants have been using ozone for disinfection since 1970s. This number may increase due to the efficacy of this process in oxidation of contaminants of emerging concern besides disinfection. Transferred ozone dose, residual ozone concentration in vent gas and in effluent are surrogate parameters currently used for the control of ozonation process but have their limitations. Disinfection of secondary treated municipal wastewater effluent using ozone was studied at pilot-scale to investigate the correlation between disinfection efficiency and surrogate parameters that are easy to monitor online. The result indicates strong correlation of E. coli and total coliform inactivation with reduction in UV absorption at 254 nm as well as color measured at 456 nm (R2 value of 0.71 to 0.86).