Which test is least likely to help an operator control a waste plant's process?

Biochemical Oxygen Demand (BOD5) measures the amount of oxygen that microorganisms will consume while decomposing organic matter in water over a specific time period, usually five days. While BOD5 is valuable for assessing the organic strength of wastewater and overall biological treatment efficiency, it does not directly indicate the operational parameters that an operator can control on a daily basis.

For example, while monitoring BOD5 can inform operators about the biological treatment capacity of the plant, it does not provide immediate actionable data to manage and optimize processes on a short-term, operational level. In contrast, tests measuring Total Suspended Solids (TSS), Chemical Oxygen Demand (COD), and nitrates all contribute more directly to day-to-day process control, as they reflect current conditions and can guide immediate operational adjustments. TSS indicates the level of particulate matter, COD gives a snapshot of organic matter that influences treatment processes, and nitrate levels are crucial for managing nitrogen removal. Therefore, BOD5, though important for assessing biological health, is less useful in real-time operational control of a wastewater treatment plant.