Page 9 - SIMPLIFIED WASTEWATER TREATMENT FUNDAMENTALS\ Advanced Activated Sludge P3

F:M Ratio cont.

Inorganic material does not contribute to the removal of the organic

fraction from the wastewater. Inorganic materials only contribute to the

weight of the sample.

For instance, a sample of MLSS weighed in the lab for suspended solids

will include the entire weight of the mixed liquor (including the inorganic

material that is not beneficial to treatment). Mixed Liquor Volatile

Suspended Solids focuses only on the organic - volatile content of the

mixed liquor.

Example MLSS = 2,350 mg/L - MLVSS = 1,850 mg/L = Volatile Content

78.7%

Note – The longer an Aeration Basin is in service, the greater likelihood of

significant accumulation of inorganic material, which leads to a reduction in

treatment capacity and a greater difference between MLSS and MLVSS.