What is the common coagulant used in water treatment processes?

The common coagulant used in water treatment processes is aluminum sulfate, also known as alum. This compound effectively destabilizes suspended particles in water, leading to their agglomeration into larger flocs that can then be removed through sedimentation or filtration. The mechanism of co-agulation involves neutralizing the charges on the particles, which allows them to bind together more efficiently.

Alum is widely used because of its effectiveness across a broad range of water qualities and conditions. Its ability to work in a variety of pH levels and its relatively low cost contribute to its popularity in water treatment facilities. This makes alum a staple in the coagulation and flocculation processes used to treat drinking water and wastewater.

Alternative options such as calcium carbonate and iron sulfate also have specific roles in water treatment but are not as commonly utilized as primary coagulants. Sodium chloride primarily serves a different purpose altogether, mainly in the context of water softening or as a disinfectant in some situations. Understanding the specific applications of these chemicals helps clarify why alum is the preferred choice for coagulant in standard water treatment processes.