The purpose of primary clarification of sewage is to remove the settleable solids by settling. Is this statement true or false?

The statement is true because primary clarification is a crucial step in the wastewater treatment process, specifically designed to remove settleable solids from sewage. During this process, wastewater flows into a large, quiescent basin where the solids are allowed to settle to the bottom due to gravity. This settling process effectively reduces the concentration of suspended solids and some of the organic material before the wastewater moves on to further treatment stages.

The effectiveness of primary clarification relies on the physical phenomenon of sedimentation, which leads to the accumulation of sludge at the bottom of the clarification tank. In addition to solids removal, this step helps to reduce the load on subsequent treatment processes, such as biological treatment, by removing a significant portion of the material that could otherwise inhibit these processes. Thus, the primary clarification plays an essential role in the overall efficiency of wastewater treatment by ensuring that a large percentage of settleable solids are removed effectively.