Which softening process would probably not meet the Surface Water Treatment Rule requirements?

Which softening process would probably not meet the Surface Water Treatment Rule requirements?

• A. Excess-lime softening
• B. Split treatment
• C. Caustic-soda treatment
• D. lime-soda ash softening

Answer: (B)

The key idea is that the Surface Water Treatment Rule requires water leaving the plant to have gone through complete, uniform treatment for the entire flow. Splitting the treatment means only part of the water receives the full treatment sequence, while the rest bypasses essential steps. That creates water that may still contain pathogens or high turbidity, so it would likely not meet SWTR requirements. Excess-lime softening, lime-soda ash softening, and caustic-soda treatment are established ways to reduce hardness within a conventional treatment train. When integrated with coagulation, settling, filtration, and proper disinfection, these processes can produce water that complies with SWTR.

The key idea is that the Surface Water Treatment Rule requires water leaving the plant to have gone through complete, uniform treatment for the entire flow. Splitting the treatment means only part of the water receives the full treatment sequence, while the rest bypasses essential steps. That creates water that may still contain pathogens or high turbidity, so it would likely not meet SWTR requirements.

Excess-lime softening, lime-soda ash softening, and caustic-soda treatment are established ways to reduce hardness within a conventional treatment train. When integrated with coagulation, settling, filtration, and proper disinfection, these processes can produce water that complies with SWTR.