Coagulation is a vital process used in water treatment to remove suspended particles and clarify water. Common coagulants include aluminum sulfate (alum), ferric chloride, and polyaluminum chloride. These chemicals work by destabilizing particles in the water, allowing them to cluster together (or coagulate) so they can be removed through sedimentation or filtration. Coagulants are particularly important in treating surface water sources, which often have higher turbidity levels.