DisinfectionQuestion 1 of 12

A WWTP disinfects final effluent with sodium hypochlorite. The outfall permit requires the plant to reduce total residual chlorine (TRC) before discharge. On today’s grab sample at the end of the contact basin, TRC is higher than the permit limit. Which chemical should the operator select to dechlorinate the effluent prior to discharge (assuming the plant is equipped for its safe feed and handling)?

A) Sodium bisulfite (NaHSO3)B) Polymer used for sludge thickeningC) Alum (aluminum sulfate)D) Hydrated lime (calcium hydroxide)

Practice Disinfection Questions