Texas Commission on Environmental Quality (TCEQ). Class C Water License Exam

What is the purpose of coagulation in water treatment?

1. To eliminate bacteria

2. To remove fine particles

3. To disinfect water

4. To enhance flavor

The correct answer is: To remove fine particles

Coagulation is a key process in water treatment aimed primarily at removing fine particles from water. During coagulation, chemical coagulants (such as alum) are added to the water, which help to destabilize and agglomerate small particulate matter that is otherwise too fine to be removed effectively by sedimentation or filtration alone. This process results in the formation of larger aggregates, known as flocs, which can then be more easily separated from the water during subsequent treatment steps, such as sedimentation or filtration. While coagulation does contribute to the overall improvement of water quality and can have an indirect effect on the presence of bacteria by removing some organic matter that serves as a food source, its main function is to clarify the water by removing those fine particles. The other answer choices, although related to water treatment processes, do not accurately reflect the primary role of coagulation. For instance, elimination of bacteria is more directly addressed through disinfection processes, and flavor enhancement and disinfection are functions associated with different treatment methods or additives, not coagulation itself.