What is referred to as Flock in water treatment?

Flock refers to small aggregates or clusters of particles that form in the process of water treatment, particularly during coagulation and flocculation. During this process, chemicals called coagulants are added to the water, which causes suspended particles to clump together into larger particles known as flocs. These flocs are typically light and fluffy in nature, making option A the correct choice.

The formation of these flocks is a crucial step in treating water because it enhances the efficiency of the sedimentation and filtration processes. Once the flocs are formed, they can settle more easily and can be removed from the water, leading to a clearer final product.

In contrast to flocks, heavy sludge typically refers to denser material that settles at the bottom of a treatment vessel, and while clear water is a goal of treatment, it does not accurately describe the clustering of particles during coagulation. Gas bubbles in water play different roles in treatment processes, such as flotation, but are not described as flock. Therefore, defining flock specifically as light and fluffy sediment highlights its importance in the water treatment process.