Which two parameters are used in the data to determine excess solids to waste?

Which two parameters are used in the data to determine excess solids to waste?

• A. Target F:M ratio and MLVSS
• B. BOD loading and volume
• C. MLVSS and BOD loading
• D. Volume and F:M

Answer: (A)

In this calculation, you’re trying to keep the right amount of active biomass in the aeration basin by balancing food coming in with how much microbial mass is available. The two data points you use are the target food-to-microorganism (F:M) ratio and the amount of active biomass, which is represented by MLVSS (mixed liquor volatile suspended solids). The target F:M ratio tells you the desired relationship between the organic loading (the “food”) and the biomass doing the treating. If the actual loading per unit biomass deviates from this target, you adjust by wasting solids. MLVSS gives you the actual amount of active biomass in the mixed liquor so you can translate that desired ratio into an actual waste rate. In other words, you need both the target F:M value and the current MLVSS to determine how much solids to waste to bring the system back to the desired operating point. BOD loading and volume don’t alone specify how much solids to waste, since they don’t directly quantify the active biomass that must be balanced against the incoming food. Volume and F:M without biomass measurement likewise don’t provide the concrete amount to remove.

In this calculation, you’re trying to keep the right amount of active biomass in the aeration basin by balancing food coming in with how much microbial mass is available. The two data points you use are the target food-to-microorganism (F:M) ratio and the amount of active biomass, which is represented by MLVSS (mixed liquor volatile suspended solids).

The target F:M ratio tells you the desired relationship between the organic loading (the “food”) and the biomass doing the treating. If the actual loading per unit biomass deviates from this target, you adjust by wasting solids. MLVSS gives you the actual amount of active biomass in the mixed liquor so you can translate that desired ratio into an actual waste rate. In other words, you need both the target F:M value and the current MLVSS to determine how much solids to waste to bring the system back to the desired operating point.

BOD loading and volume don’t alone specify how much solids to waste, since they don’t directly quantify the active biomass that must be balanced against the incoming food. Volume and F:M without biomass measurement likewise don’t provide the concrete amount to remove.