DisinfectionQuestion 1 of 12

A Texas WWTP is evaluating two disinfection alternatives for its final effluent: (1) sodium hypochlorite with downstream sulfur dioxide dechlorination, or (2) peracetic acid (PAA) with no dechlorination step. The plant discharges to a small stream where the permit has a strict total residual chlorine (TRC) limit and the operator is concerned about forming disinfection byproducts (DBPs). Which statement best supports selecting PAA over chlorine for this situation?

A) PAA disinfection typically costs less than hypochlorite plus dechlorination at most plants because PAA has a lower chemical cost per gallon and requires no operator attention.B) PAA can provide effective disinfection without forming chlorinated DBPs, and it does not create TRC so a separate dechlorination step is typically not needed to meet a TRC limit.C) PAA leaves a stable chlorine residual that protects the outfall and receiving stream, which is why it eliminates the need for dechlorination.D) PAA is always more effective than chlorine, so it will consistently deliver lower fecal coliform regardless of contact time, mixing, or effluent quality.

Practice Disinfection Questions