Which chemical is commonly used to control pH levels in water treatment?

• A. Sodium bicarbonate
• B. Calcium sulfate
• C. Carbon dioxide
• D. Aluminum sulfate

Answer: (C)

Carbon dioxide is commonly used to control pH levels in water treatment because it reacts with water to form carbonic acid, which helps lower the pH. This process is particularly effective because carbon dioxide is a naturally occurring gas that can be easily dissolved in water to achieve the desired pH balance.

In water treatment, managing pH is important for several reasons, including optimizing the effectiveness of disinfectants and minimizing corrosion of pipes. By introducing carbon dioxide, operators can adjust the pH to a level that enhances water quality and safety.

Sodium bicarbonate and calcium sulfate are also used in water treatment but have different primary functions. Sodium bicarbonate can act as a buffer to stabilize pH, while calcium sulfate primarily contributes hardness and does not effectively lower pH on its own. Aluminum sulfate, on the other hand, is primarily used as a coagulant in water treatment processes rather than for pH adjustment.