American Water College Practice Test 2026 - Free Practice Questions and Comprehensive Study Guide

The process that is primarily responsible for the separation of suspended solids from wastewater is primary clarification. This step occurs after preliminary treatment and is focused on the physical separation of solids from liquids. In primary clarification, wastewater flows into large sedimentation tanks where gravity allows the heavier suspended solids to settle at the bottom, forming sludge. Meanwhile, lighter materials such as grease and oils float to the surface, forming a scum layer.

This process effectively reduces the concentration of suspended solids and organic materials before the wastewater undergoes further treatment, such as secondary treatment, where biological processes further reduce remaining pollutants. While filtration and aeration involve the removal of solids and the addition of oxygen respectively, they do not primarily focus on the separation of suspended solids as primary clarification does.