MCRT

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DanHalen

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Last fall I signed up for a PE review course and went through all of their problems with a fine tooth comb. Unfortunately, I've ran across a snag this week and found a discrepancy with the MCRT equation. The equation is:

Theata = (VX)/(QwXr)​
Where,​
V = Volume of aeration tank​
X = MLVSS (prep class is using MLSS)​
Qw = Waste flow rate​
Xr = Microorganism concentration in the sludge return line​

The issue is that the prep class is using MLSS for X instead of MLVSS. So which is it? CERM and the Davis and Cornwell books that I have states that X = MLVSS, not MLSS.

 
Both terms are used. MLVSS is more representative and is now preferred, but MLSS is easier to determine in the lab and has been in use for a long time.

 
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