Following coagulation, what is the next step in a physical-chemical treatment process?

In a physical-chemical treatment process, following coagulation, the next step is typically flocculation. During coagulation, chemicals are added to the water to destabilize and agglomerate suspended particles into larger clumps called flocs. Flocculation is the process that follows, where gentle mixing occurs to encourage the formation of these larger floc aggregates, making it easier for them to settle out during subsequent treatment stages.

The purpose of flocculation is to enhance the efficiency of the sedimentation process that will occur later, allowing for a greater volume of suspended solids to be removed from the water. This is critical for the overall efficiency of wastewater treatment, as it prepares the mixed solutions for better settling performance.

While filtering might seem necessary afterward, it generally follows settling. Disinfection comes after that phase to ensure any remaining pathogens are dealt with. Additionally, settling is indeed an integral part of the process but occurs after flocculation, marking it as a subsequent stage rather than the immediate next step. Thus, flocculation is correctly identified as the next step following coagulation in a physical-chemical treatment process.