Which of the following is a common example of a base in water treatment?

Calcium hydroxide is commonly used in water treatment processes due to its properties as a strong base. It is often employed to adjust the pH of water, promoting conditions that facilitate the effective removal of contaminants and ensuring water quality standards are met. The addition of calcium hydroxide can help in precipitating heavy metals, enhancing flocculation in sedimentation processes, and controlling scale formation in water systems.

In contrast, sodium bicarbonate is a weaker base and is typically used for buffering rather than for significant pH adjustment. Carbon dioxide, while important in some water treatment processes, acts as an acid when dissolved in water. Sulfuric acid, on the other hand, is an acid and is used to lower pH instead of increase it. Thus, calcium hydroxide stands out as a prime example of a base that plays a vital role in the treatment of water.