What do the terms "coagulation" and "flocculation" refer to in water treatment?

Coagulation and flocculation are critical processes in water treatment that specifically aim to remove suspended solids from water. Coagulation involves the addition of coagulants, such as alum or iron salts, which destabilize the charged particles in water. This destabilization promotes the aggregation of these particles, allowing them to clump together into larger particles known as flocs.

Once coagulation occurs, flocculation follows, where these tiny flocs come together to form larger clusters. This step typically involves gentle agitation that encourages further aggregation without breaking apart the formed flocs. The resulting larger particles are then more easily removed from the water through sedimentation or filtration.

These processes do not pertain to disinfecting water, as their primary function is solid removal rather than pathogen killing. They also do not relate directly to microbial processes or chemical pollution. Thus, they are fundamentally about enhancing the physical clarity of water by effectively removing suspended solids, debris, and particles that can impair water quality.