Disinfection of the final effluent is required for the protection of public health from disease causing microorganisms. At Norwalk WPCF, a strong bleach solution (sodium hypochlorite) is used to kill any remaining organisms in the water following the final settling tanks. A second chemical (sodium bisulfite) is then used to neutralize the bleach prior to discharging the clean water to the Norwalk River.
Disinfection & Dechlorination