In part 1, I showed you how to do process control with and aeration, a flowmeter and wasting mixed liquor. Now you are going to complain about wasting mixed liquor. So now I will show yoyu how to do it with RAS
Lets review the conditions
Flow = 2 MGD
RAS Flow + 1 MGD
Aeration tank volume = 1 MGD
The RAS will be more concentrated than the MLSS, so we have to find the concentration factor.
Isn't that east? No sampling or analysis and no nagging from me to do your sampling right
For the next lesson wil will add the clarifier mixed liquor inventory and not use the lab.
The concentration factor is: Influent Flow+RAS Flow/RAS Flow
Or 2 MGD + 1 MGD/1 MGD = 3/1 = 3
By mass balance the RAS is 3 times as concnetrated as the MLSS.
So, the RAS flow needed to maintain an 8 day MCRT is 1 MG/8/3 or 125,000/3 = 41,700 gallons
If you have problems with this call me at 419-367-2749
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