Page 27 - SIMPLIFIED WASTEWATER TREATMENT FUNDAMENTALS\ Advanced Activated Sludge P3

SRT vs MCRT cont.

Applied SRT Example

Factors:

Influent Flow 1.0 MGD Aeration Basin Volume 430,100 gallons Aeration Basin

MLVSS 2,350 mg/L WAS TSS 5,600 mg/L WAS 1,500 GPD Effluent TSS 15 mg/L

Aeration Pounds 0.4301 MG x 2,350 mg/L MLVSS x 8.34 lbs/gal = 8,430 lbs

WAS Pounds 0.015 MG x 5,600 mg/L TSS x 8.34 lbs/gal = 701 lbs

Effluent TSS 15 mg/L x 1.0 MGD x 8.34 lbs/gal = 125 lbs

Total pounds lost from the system 701 lbs + 125 lbs = 826 lbs

8,430 lbs ÷ 826 lbs = 10 Day SRT

Note – WAS should follow a planned SRT target, not reactively set to reduce Secondary Clarifier

blanket level.