Which coagulant is most widely used in water treatment?

The most widely used coagulant in water treatment is aluminum sulfate, commonly referred to as alum. This compound is effective in destabilizing colloidal particles suspended in water, allowing them to agglomerate and form larger flocs that can be easily removed during the sedimentation process. Aluminum sulfate works by neutralizing the negative charges on particulates, which prevents them from remaining suspended in the water and promotes their removal during sedimentation and filtration stages.

Alum is favored for its cost-effectiveness, wide availability, and proven effectiveness in various types of water treatment applications, including drinking water purification and wastewater treatment. Its ability to function well across a range of pH levels further enhances its practical application in municipal settings.

In contrast, while other coagulants like ferric chloride are also effective, aluminum sulfate remains the predominant choice due to its balance of performance, affordability, and ease of use.