What information is required to calculate the Food-to-Microorganisms (F/M) ratio?

To calculate the Food-to-Microorganisms (F/M) ratio, it is essential to know both the amount of biodegradable organic matter available as food for microorganisms and the concentration of those microorganisms in the system. The correct answer involves the use of BOD in pounds and MLVSS in pounds.

Using BOD in pounds represents the mass of organic material (food) that can be utilized by microorganisms, providing a clear quantitative measure for calculation. MLVSS (Mixed Liquor Volatile Suspended Solids) in pounds quantifies the actual mass of the active biomass present in the system that can consume this organic matter. The F/M ratio is then calculated by dividing the mass of BOD (food) by the mass of MLVSS (microorganisms), giving a dimensionless ratio that is pivotal in evaluating the balance between food supply and microbial mass.

This method is advantageous because both measurements are expressed in the same unit (pounds), ensuring consistency and ease of calculation. In contrast, other combinations of BOD and MLVSS that involve different units, like mg/L, complicate the calculation and may lead to misunderstandings or inaccurate results. Hence, the chosen answer provides the necessary parameters in a suitably consistent format for calculating the F