During water treatment, which reaction is commonly enhanced at lower pH levels?

• A. Chlorination
• B. Coagulation
• C. Filtration
• D. Flocculation

Answer: (B)

The process of coagulation is commonly enhanced at lower pH levels during water treatment. At lower pH, the surface charges on colloidal particles tend to become more positive, which reduces their repulsion from one another. This allows the particles to come closer together and facilitates the formation of larger aggregates, or flocs.

Coagulation typically involves the addition of coagulants, such as aluminum sulfate or ferric chloride, that neutralize the charges on suspended particles. The effectiveness of these coagulants can vary depending on the pH of the water. In acidic conditions, coagulants often work more effectively, leading to better particle aggregation and removal during the sedimentation process.

Understanding this is crucial for water treatment operators, as pH adjustments can lead to improved treatment performance, particularly in systems where turbidity is an issue. This knowledge enables operators to optimize coagulation processes and ensure effective removal of contaminants from water.