Question

2. A completely mixed activated sludge process is designed to treat 20,000 m/d of domestic wastewater having a BODs concentration of 250 mg/L following primary treatment. The NPDES permit requirement for effluent BODs and TSS is 20 mg/L for each. The biokinetic parameters have beern established as: yield 0.6, k 5/d, K-60 mg/L, and kd 0.06/d. The MLVSS concentration in the aeration tank is to be maintained at 3000 mg/L and the ratio of VSS/TSS is 0.75. Assume that the particulate BOD5 oxygen demand is approximately 95% of the effluent VSS. The secondary clarifier concentrates the settled solids to 10,000 mg/L Determine: (a) the effluent soluble BODs (sBODs) necessary to meet the NPDES effluent total BODs (tBODs) requirement of 20 mg/L (b) the solid residence time required (c) the volume of the aeration basin in m (d) the mass of sludge produced (kg/d) (e) the organic loading rate on a mass basis (F/M loading rate) (f) the organic loading rate on a volumetric basis (g) the volumetric sludge wasting rate (m'/d) from the underflow of the secondary clarifier (compare the approximation approach in Mihelcic to the more precise approach in the FE Handbook. down, or remain the same?

Answer 1

Q,= 20,000 m3 Ida kg vss/ kg Bo D 5 ___ y ield coeficient d O day IS6omg IL TSS 20 IL S124,.703 m S o P1 2.0,000 1202 03Bla we e X3000