Which stage of sewage treatment is responsible for the removal of suspended solids?

Primary treatment

The process in sewage treatment that removes suspended solids is (c) Primary treatment.

Primary treatment is the initial step in sewage treatment where the removal of suspended solids takes place. During primary treatment, sewage undergoes physical processes to separate large and small particles from the wastewater. This is achieved through the processes of filtration and sedimentation.

In filtration, the sewage is passed through screens or mesh filters that trap and remove larger debris, such as plastics, rags, and other solid materials. This helps in preventing clogging and damage to downstream equipment.

After filtration, the wastewater enters the sedimentation tanks, also known as primary clarifiers. In these tanks, the flow of wastewater is slowed down, allowing the suspended solids to settle to the bottom due to gravity. This forms a layer of sludge, which is periodically removed for further treatment.

The primary treatment process effectively removes a significant amount of suspended solids from the sewage, reducing its organic load and improving the quality of the wastewater before it undergoes further treatment in secondary and tertiary stages.

It's important to note that while primary treatment removes suspended solids, it does not eliminate dissolved pollutants or pathogens from the sewage. Additional treatment steps are required to address these aspects in secondary and tertiary treatment processes.

Therefore, in sewage treatment, the primary treatment stage specifically focuses on the removal of suspended solids from the wastewater.