Page 13 - SIMPLIFIED WASTEWATER TREATMENT FUNDAMENTALS\ Advanced Activated Sludge P3
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Biomass Inventory Relationship to F:M Ratio
In the winter season, when metabolisms slow down, the process plan
may dictate a need for more biomass. In this example, Process Control
dictates a further increase in biomass inventory to 3,500 mg/L MLVSS:
0.4031 MG x 3,500 mg/L MLVSS x 8.34 lbs/gal = 11,766 lbs
1,542 lbs of BOD (Food) ÷ 11,766 lbs (Mass) = 0.13
As you can see, the more pounds that are added in the biomass
inventory, the lower the F:M ratio. In nutrient removal, where an
additional biomass population of microorganisms (Autotrophic
organisms like Nitrosomonas and Nitrobacter) are needed in addition to
the Heterotrophs, biomass inventory will increase the biomass
population, driving the F:M Ratio further down.
