What is formed when a coagulant reacts with alkalinity in the raw water?

When a coagulant reacts with alkalinity in raw water, the primary outcome is the formation of floc. Coagulation is a critical process in water treatment where chemical coagulants, such as aluminum sulfate or ferric chloride, are added to raw water. These coagulants neutralize the electrical charges on suspended particles, allowing them to clump together (or coagulate) into larger aggregates known as floc.

The presence of alkalinity in the water helps to facilitate this process. Alkalinity acts as a buffering agent that can help maintain a suitable pH level during coagulation, which is crucial for effective floc formation. The resulting floc can then be more easily removed from the water during subsequent treatment stages, such as sedimentation or filtration.

This process is essential for producing clean drinking water, as floc removal helps to reduce turbidity and eliminate pathogens and other harmful substances from the water supply.