Basic Wastewater Operator Practice Exam

What is the primary function of a clarifier in wastewater treatment?

1. To disinfect wastewater

2. To remove solids from liquids

3. To aerate the wastewater

4. To pump liquids out of the system

The correct answer is: To remove solids from liquids

The primary function of a clarifier in wastewater treatment is to remove solids from liquids. Clarifiers are designed to help separate suspended solids in the wastewater from the liquid phase, allowing for gravity settling of these solids. As wastewater flows into the clarifier, the flow rate slows down, enabling heavier particles to settle to the bottom where they form a sludge layer. The clarified liquid, which is now significantly lower in suspended solids, overflows at the top of the clarifier for further treatment. This process is crucial in reducing the overall solids load on subsequent treatment processes and helps improve the quality of the effluent leaving the treatment facility. Other functions, such as disinfection or aeration, are conducted in separate treatment processes designed specifically for those purposes, and pumping systems are typically employed after the clarification process to move treated water to the next stage. Thus, the clarifier plays a vital role in streamlining the efficiency of the overall wastewater treatment system.