What is the primary purpose of coagulants in water treatment?

Coagulants play a crucial role in the water treatment process primarily by promoting the settling of solids. When water contains suspended particles, such as dirt, silt, and microbes, these particles need to be removed to ensure the water is clean and safe for consumption. Coagulants, often used in the form of aluminum sulfate or ferric chloride, cause tiny particles to clump together into larger aggregates known as flocs.

These flocs are then easier to remove through sedimentation or filtration processes. By enhancing the flocculation process, coagulants improve the efficacy of sedimentation basins where the heavier flocs settle to the bottom, leaving clearer water on the surface. This step is essential for reducing turbidity and removing harmful microorganisms, contributing significantly to the overall effectiveness of the water treatment process.

The other choices highlight activities that do not align with the primary function of coagulants. Increasing water temperature is unrelated to coagulation, while disinfection pertains to the elimination of pathogens, which is usually achieved through chemical disinfectants or UV light rather than coagulants. Adding nutrients does not serve the goal of improving water quality for drinking, making it irrelevant in the context of coagulants' purpose.