Case Study

Removal Of Disinfection By-Product With Chlorine Dioxide

Source: Evoqua Water Technologies

Removal Of Disinfection By-Product With Chlorine Dioxide

This municipality disinfects 1-1.5 million gallons per day of drinking water, and is currently transitioning from a small system serving <10,000 people to a large system serving >10,000 people. Chlorine gas was used as the primary disinfectant for the raw water entering the plant. THM’s levels consistently averaged 64 μg/L, the trigger limit for disinfection profiling. HAA5’s averaged 48 μg/L, and TOC reduction was consistently between zero and the required removal rate of 25%. Reducing the levels of THM’s, HAA5’s and TOC and meeting compliance standards for both the Stage 1 D/BPR and the LT1 Enhanced Surface Water Treatment Rule prompted the municipality to consider different pre-oxidants and alternative disinfectants.