Coagulation in water treatment is primarily what type of process?

Coagulation in water treatment is primarily a chemical process because it involves the addition of chemical coagulants, such as aluminum sulfate or ferric chloride, to the water. These chemicals interact with suspended particles and impurities, causing them to aggregate into larger clusters known as flocs. This process enhances the removal of these particles during sedimentation and filtration, thus improving the quality of the water being treated.

In contrast, physical processes typically involve changes in the physical state of the water or its components without chemical reactions, mechanical processes refer to physical actions like stirring or mixing, and biological processes involve living organisms to break down contaminants. In coagulation, the chemistry of the coagulants plays a crucial role in facilitating the aggregation of impurities, making it a distinctly chemical process.