Ontario Operator-in-Training (OIT) Practice Exam

Why are acids and bases used in water treatment?

1. To add flavor

2. To release harmful contaminants

3. To adjust pH for optimal treatment processes

4. To remove solid particles

The correct answer is: To adjust pH for optimal treatment processes

Acids and bases play a crucial role in water treatment primarily for the purpose of adjusting pH levels. The pH level of water is critical for various treatment processes, such as coagulation, sedimentation, and disinfection. Most chemical treatments work best within a specific pH range, so maintaining the appropriate pH ensures that these processes function effectively and efficiently. For example, in coagulation, if the water's pH is too high or too low, the coagulants may not perform well, leading to ineffective removal of pollutants. Additionally, certain disinfection methods, such as chlorine disinfection, are more efficient at specific pH levels. By using acids and bases to adjust pH, operators can optimize these treatment processes, ensuring cleaner and safer water for distribution.