- Food in F/M is usually BOD5 in lbs or kg per day. The 5 day lag in data can be a problem so many systems use either COD or TOC as a substitute. If you want to use either COD or TOC, you need to find the average ratio of either to BOD5 to compare your F/M to other systems or design parameters.
- M is often referred to as microorganisms - again in lbs or kg. I favor calling M - the mass as it includes living microbes, dead microbes, EPS, adsorbed organics, and particulates in a matrix. Typically we use MLVSS as the proxy for M, but some systems use MLSS which requires less time and equipment. Just note which test you are using!
In addition to F/M consider the following parameters that you probably already run
- MCRT (mean cell residence time)
- Microscopic exam
- Clarifier bed depth
- Oxygen Uptake Rates (OUR & SOUR)
- D.O. in aeration basin
- Molecular testing (qPCR and MCA) - a less frequent test but very powerful as it looks directly at the microbes functioning in the system.