What are the two primary benefits of using sodium hydroxide in water treatment?

Sodium hydroxide, commonly known as caustic soda, is primarily used in water treatment to raise the pH of water. This adjustment is important because many water treatment processes, such as coagulation and the removal of heavy metals, function optimally within certain pH ranges. By increasing the pH, sodium hydroxide facilitates the precipitation of heavy metals, allowing them to be more effectively removed from the water.

In addition to adjusting pH, an elevated pH level can enhance the efficiency of coagulants used in the treatment process, fostering better floc formation and sedimentation. Therefore, the dual benefits of raising pH and promoting the removal of heavy metals highlight sodium hydroxide's critical role in maintaining water quality and ensuring effective treatment processes.

While other options discuss various aspects of water treatment, they do not capture the primary functions of sodium hydroxide as accurately, which center around pH adjustment and heavy metal removal.