What is the primary purpose of coagulants in water treatment?

The primary purpose of coagulants in water treatment is to aid in the formation of larger particles, a process known as coagulation. Coagulants are chemical substances, typically salts of aluminum or iron, that are added to water to destabilize colloidal particles. When coagulants are introduced into the water, they neutralize the charges on these fine particles, allowing them to agglomerate into larger aggregates. These larger particles, or flocs, can then be more easily removed from the water through sedimentation or filtration processes.

This process is crucial in the treatment of water as it enhances the removal rates for impurities and contaminants, improving overall water quality before it undergoes further treatment stages, such as disinfection. While pathogens may be dealt with via disinfection methods and sediments may be removed through various filtration and sedimentation techniques, the specific role of coagulants is centered on the aggregation of particles, which enhances the efficiency of subsequent water treatment processes.