In a water treatment plant using direct filtration, which step of conventional treatment is excluded?

In a direct filtration process, the step that is excluded from conventional water treatment is sedimentation. Conventional water treatment typically follows a sequence that includes coagulation, flocculation, sedimentation, and finally, filtration.

In sedimentation, larger particles and flocs that form during the coagulation and flocculation stages settle out by gravity to form a sludge layer at the bottom of a sedimentation basin. However, in direct filtration systems, this step is omitted to streamline the process and allow for faster treatment. Instead of allowing time for the solids to settle out before filtration, direct filtration uses specialized equipment and techniques to capture particulates during the filtration stage itself. This approach is often used in situations where water quality is relatively good, or where rapid treatment is necessary.

Thus, understanding the process of direct filtration helps clarify why sedimentation is excluded, as it emphasizes efficiency and quick delivery of treated water while still ensuring adequate removal of contaminants through enhanced filtration techniques.