What is the function of primary treatment in wastewater treatment?

The function of primary treatment in wastewater treatment is primarily focused on the removal of large solids and sediment from the wastewater. During this initial stage of treatment, the wastewater undergoes screening processes to eliminate larger debris like sticks, plastics, and other solid materials. Subsequently, the wastewater is allowed to settle in a sedimentation tank, where heavier solids settle to the bottom, forming sludge, while lighter materials rise to the top and can be removed as scum.

This step is crucial because it prevents larger particles from causing issues in subsequent treatment processes, ensuring that the more refined treatments can effectively target dissolved and smaller particles. By efficiently removing these larger solids, primary treatment enhances the overall efficiency and effectiveness of the wastewater treatment system.

Other methods such as disinfection typically occur in later treatment stages, as well as the biodegradation of organic matter, which is handled in secondary treatment. Nutrient filtration and removal are also addressed in different phases of treatment. Thus, the primary focus is clearly on the removal of large particulates to prepare the wastewater for the next stages of treatment.