California Wastewater Treatment Operator Practice Exam

What is the role of a clarifier in wastewater treatment?

1. To disinfect wastewater

2. To aerate wastewater

3. To separate solids from liquids

4. To remove pathogens

The correct answer is: To separate solids from liquids

The role of a clarifier in wastewater treatment is to separate solids from liquids. In this process, wastewater enters the clarifier where its velocity is reduced, allowing suspended solids, such as organic matter and other particulates, to settle to the bottom of the tank due to gravity. This settled material is referred to as sludge. Concurrently, the clarified liquid, or supernatant, rises to the top and is typically directed to subsequent treatment processes. Clarifiers are crucial in the treatment process because they help to reduce the load on downstream processes, such as biological treatment or disinfection, by removing a significant amount of suspended solids early in the treatment cycle. By concentrating the solids in one area, clarifiers also facilitate the management and removal of sludge, which is essential for maintaining system efficiency. The other processes mentioned in the question, such as disinfection and aeration, are handled in different parts of the wastewater treatment system, each serving a specific function in overall treatment.