What is generally the first step in the water treatment process?

Coagulation is generally recognized as the first step in the water treatment process. This phase is crucial because it initiates the removal of suspended particles and impurities from the water. During coagulation, chemicals known as coagulants (commonly aluminum sulfate or ferric chloride) are added to the water. These substances promote the aggregation of tiny particles, forming larger clusters known as flocs.

The floc formation is essential as it significantly enhances the efficiency of subsequent processes such as sedimentation and filtration. By converting smaller, dispersed particles into larger aggregates, coagulation improves the removal of contaminants that would otherwise remain suspended in the water.

In contrast, sedimentation occurs after coagulation and relies on gravity to separate the formed flocs from the water. Although filtration is vital for further purification, it takes place after these initial steps. Disinfection, which is critical for killing harmful pathogens, is typically one of the last steps in the treatment process to ensure that water is safe for consumption. Thus, coagulation sets the foundation for efficient treatment by preparing the water for the following processes.