Tennessee Wastewater Operator Practice Exam

Why is supernatant sampled and analyzed?

1. To determine its viscosity

2. To predict impacts to liquid stream processes

3. To measure nutrient concentrations

4. To assess odor compounds

The correct answer is: To predict impacts to liquid stream processes

Supernatant is the clear liquid that remains above the solid residue after sedimentation in wastewater treatment processes. Sampling and analyzing the supernatant is critical because it provides valuable information regarding the characteristics of the liquid phase of the wastewater. Sampling supernatant allows operators to predict impacts to liquid stream processes as it contains a significant amount of dissolved and suspended material that can affect downstream biological treatments, chemical dosing, or filtration processes. For instance, if high nutrient concentrations, turbidity, or the presence of certain inhibitors are detected in the supernatant, it can indicate potential challenges in processing that would need to be addressed to maintain operational efficiency. Understanding these parameters ensures that operators can effectively manage the treatment process and optimize the removal of contaminants while preventing issues such as clogging or reduced treatment efficiency further along in the system. While measuring nutrient concentrations and assessing odor compounds are important aspects of wastewater treatment, the specific focus on predicting impacts on liquid stream processes directly ties into operational decision-making and the overall health of the treatment system, making it a key reason for sampling and analyzing supernatant.