Design a fully mixed activated sludge system for a wastewater with the following characteristics:

Average Flow: 6.30 MGD (millions of gallons per day) BOD5 input =240 mg/l Suspended Solids (TSS) input = 280 mg/l Maximum BOD5 in effluent = 30 mg/l

Assumptions: BOD5 removed in primary clarifier = 33% TSS removed in primary clarifier = 67% MLVSS/MLSS = 80% Oxygen consumption is 1.42 mg/mg of oxidized Specific gravity of primary solids = 1.05 Solids content in primary sludge = 4.5% effluent = soluble escaping treatment (S) + suspended solids Treatment efficiency= S0 S X 100% S0 Width: Length in aeration tank = 1:3 Aeration tank depth = 12 ft. Maximum Suspended Solids in effluent = 30 mg/l Ks=100mg/l BOD5 m = 2.5/day Mixed Liquor Suspended Solids (MLSS) = 3500 mg/l Y = 0.5 mg VSS/mg BOD5 removed kd = 0.06/day BOD5 /BODultimate = 0.67

Determine:

1. Loads of and TSS entering the plant (lb/day) (10%) 2. Concentration of primary solids (mg/l) (5%) 3. Entering the Aeration Tank (15%) a. Flow ( /s) (5%) b. (mg/l) (5%) c. TSS (mg/l) (5%)

4. BOD5 of the suspended solids in the effluent (assume 65% of it is biodegradable) (mg/l) (10%) 5. Untreated soluble BOD5 (mg/l) (5%) 6. Biological treatment efficiency (%) (10%) 7. Treatment plant efficiency (%) (10%) 8. Volume of the aeration tank (cubic meters and millions of gallons) (25%) 9. Dimensions of the aeration tank (10%) a. Width (ft.) b. Length (ft.)