Which of the following is NOT a key operational parameter to monitor in a wastewater treatment plant?

Monitoring key operational parameters in a wastewater treatment plant is essential for ensuring the efficiency and effectiveness of the treatment process. Parameters such as pH, temperature, and dissolved oxygen are critical because they directly influence biochemical processes, the health of microorganisms, and the overall performance of the treatment system.

pH is vital because it affects the biological activity within the treatment system; organisms that break down waste can be sensitive to changes in pH. Temperature also plays an important role as it can impact the reaction rates of biochemical processes and the solubility of oxygen in water. Dissolved oxygen is crucial for aerobic treatment processes, as microorganisms require oxygen to efficiently break down organic matter.

On the other hand, while sound levels may provide general information about equipment operation, they are not a critical parameter that directly affects treatment performance. Sound levels might indicate mechanical issues or operational irregularities, but they do not provide insight into the chemical or biological processes occurring within the treatment plant. Therefore, sound level is not considered a key operational parameter that must be routinely monitored compared to the others listed.