Question

(30 points) A completely mixed activated sludge system comprised of an aerated reactor and a secondary clarifier with sludge return is going to treat 15,000 m/d of industrial wastewater. The primary effluent going to the reactor has a BODs of 1,100 mg/L that must be reduced to 150 mg/L prior to discharge to a municipal sewer. The pilot study was conducted and generated the following results: 3. Mean cell residence time- 5 day, MLSS concentration in the reactor 7.200 mg/L MLSS/MLVSS=12, Y (yield coefficient) is 0.7 kgVSS /kgBOD5, and k.-0.03 d- Determine the following: a. (5 points) hydraulic retention time and volume of the reactor. b. (5 points) BOD loading rate in kg BODs/m2 d to the aeration tank c. (5 points) The F/M ratio in the reactor d. (5 points) The mass and volume of solids wasted each day, at return sludge are obt concentration Xr= 12,000 mg/L (5 points) The sludge recirculation ratio, R= QnQ (5 points) The volume of solids that must be wasted each day, if the solids are wasted directly from the activated sludge reactor instead of from the underflow of the secondary clarifier. e. f.

Answer 1

コ200(1+003x5) ー→V= 6825 000 8280 V- 824.27m3 Hydraulic Retention Time -8211, 27 X24-13th V G- ls000 (b) ROD Looding rale- - QSo 82 y. 29 624.2구 x 7200 Scanned with amscanner

Sludge wosted voluune 5 = 824.23× 200 5x12000 e fudge Recrcudation Ratio 4200 子200 12.000 200 CS Scanned with CamScanner