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NPDES Lab Manual

Wastewater Activated Sludge Desired F/M
(food to microorganism) Ratio

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The F/M ratio calculation is just one of the process control parameters you should monitor in your activated sludge system. The following are suggested operating parameters for F/M Ratio. The optimum F/M ratio for your plant can only be determined by monitoring facility performance through regular process control testing.

Conventional Activated Sludge (F/M) 0.2  -  0.5
Contact Stabilization (F/M) 0.15  -  0.2
Extended Aeration (F/M) 0.01  - 0.07
Step Aeration (F/M) 0.2  - 0.5
Two-Stage Aeration (F/M) 0.07  -  0.15