In water treatment, what does “coagulation” do?

Coagulation is a critical process in water treatment that primarily serves to remove suspended particles and colloids from water. During this process, coagulants, such as aluminum sulfate or ferric chloride, are added to the water. These substances have a positive charge that neutralizes the negative charges of suspended particles, allowing them to clump together into larger aggregates known as flocs. This aggregation makes it significantly easier to remove these particles during subsequent steps in the treatment process, such as sedimentation and filtration.

Removing suspended solids and colloids is essential for improving water clarity and quality, as these impurities can harbor pathogens, lead to taste and odor issues, and cause problems in disinfection processes. Thus, coagulation plays a pivotal role in ensuring that the treated water is safe for consumption.

Other options do not accurately describe the coagulation process; for example, while the process may indirectly affect algae growth by improving water quality, preventing algae growth is not its primary function. Similarly, coagulation does not add minerals for taste or enhance acidity, as its focus is specifically on the removal of particulates rather than altering the chemical composition of the water in these ways.