Stage 2 DBPR includes a provision to reduce or eliminate the use of chlorine disinfectants at the beginning of the treatment process if TOC exceeds 2.0 mg/L.

Stage 2 DBPR includes a provision to reduce or eliminate the use of chlorine disinfectants at the beginning of the treatment process if TOC exceeds 2.0 mg/L.

• A. False
• B. Not specified
• C. True
• D. Depends on pH

Answer: (C)

Total Organic Carbon (TOC) is a measure of the organic matter in water that can react with chlorine to form disinfection by-products. In Stage 2 DBPR, operators manage disinfection by optimizing when and how much chlorine is used, aiming to minimize DBP formation while still achieving the required disinfectant residual later in the treatment train. When TOC exceeds a 2.0 mg/L threshold, the rule allows reducing or temporarily eliminating chlorine at the beginning of the treatment process so that TOC can be removed through coagulation, sedimentation, and filtration before disinfection. This sequencing helps lower DBP formation by limiting chlorine's contact with organic precursors, yet still ensures adequate disinfection is maintained downstream. Therefore, this statement is true.

Total Organic Carbon (TOC) is a measure of the organic matter in water that can react with chlorine to form disinfection by-products. In Stage 2 DBPR, operators manage disinfection by optimizing when and how much chlorine is used, aiming to minimize DBP formation while still achieving the required disinfectant residual later in the treatment train. When TOC exceeds a 2.0 mg/L threshold, the rule allows reducing or temporarily eliminating chlorine at the beginning of the treatment process so that TOC can be removed through coagulation, sedimentation, and filtration before disinfection. This sequencing helps lower DBP formation by limiting chlorine's contact with organic precursors, yet still ensures adequate disinfection is maintained downstream. Therefore, this statement is true.