Question

Please show all work and formulas used. Thanks!

The following data are given for an activated sludge process:

Q = 5 MGD

BOD₅ (influent) = 250 mg/L (soluble)

BOD₅ (effluent) = 20 mg/L (soluble)

MCRT = 10 days

MLSS in the aeration tank = 2500 mg/L

Concentration of SS in the recycle line = 10,000 mg/L

Concentration of SS in the effluent = 30 mg/L (70% biodegradable)

BOD₅/BOD_u = 0.75, No nutrient limitations.

Yield co-efficient, Y = 0.65

Endogenouse decay coefficient, k_d = 0.06/day

Determine:

(a) Find soluble BOD₅ (in mg/L) in the effluent, BOD₅ treatment efficiency (in %) and overall efficiency (in %).

(b) Find hydraulic detention time (in hours) and the volume of tank (in MG).

(c) Y_obs and biomass production (in lb VSS/day)

(d) Q_w (in MGD) when the wasting from the AT and from recycle line.

(e) Recirculation ratio

(f) Find Specific Utilization rate (U) and food to microorganism (F/M) ratio

(g) Calculate volumetric loading rate (lb BOD₅ /1000 ft³)

Answer 1