What is the purpose of a clarifier in a wastewater treatment plant?

The purpose of a clarifier in a wastewater treatment plant is primarily to remove solids from wastewater. Clarifiers operate through the process of sedimentation, where suspended solids settle to the bottom of the tank due to gravity. The settled sludge is then removed from the bottom of the tank, effectively separating the solids from the liquid effluent. This step is crucial in the treatment process, as it helps to reduce the load of solids in the water, making it cleaner and more manageable for subsequent treatment processes.

While disinfection, aeration, and nutrient addition are important processes in wastewater treatment, they are not the primary functions of a clarifier. Disinfection typically occurs in later stages of treatment to eliminate pathogens. Aeration involves introducing air to support the growth of microorganisms that degrade organic matter, and nutrient addition is often used to enhance biological processes in specific treatment systems. Therefore, the main role of the clarifier is indeed focused on solid removal, confirming that option B is the correct choice.