What is formed when a coagulant reacts with finely divided and suspended material in raw water?

When a coagulant reacts with finely divided and suspended material in raw water, it forms a floc. This process is known as coagulation, which is critical in water treatment. During coagulation, the coagulant, typically a chemical such as aluminum sulfate or ferric chloride, neutralizes the electric charges on the fine particles in the water.

As the particles begin to collide and bind together, they form larger aggregates known as floc. This agglomeration improves the removal of these particles from water during subsequent treatment processes such as sedimentation and filtration. Floc is essential in creating conditions conducive to effective removal of impurities, thus ensuring better water quality.

The term "sediment" typically refers to the settled solids that accumulate at the bottom of a container after a period of inactivity and is not directly the result of coagulation. "Scum" refers to the layer of organic material that floats on the surface of a liquid, typically not the direct outcome of coagulation. On the other hand, "sludge" is used to describe the layer of solids that settle at the bottom after coagulation and sedimentation has occurred, but is not synonymous with floc itself, which is the initial agglomerate formed during the coagulation