300 mL of wastewater was collected, aerated and seeded with bacteria. The dissolved oxygen content was 7.4 mg/L initially. After 5 days, the dissolved oxygen content had dropped to 2.3 mg/L. Estimate the BOD, and the ultimate BOD? Assume that k (base e) = 0.20 day %3D

An anaerobic digester (AD) is designed with the following data. Organic loading rate 1.0 kg VSS/m³.day VSS load 120 kg/day (i). (ii). Estimate the volume of the AD. If the VSS is 12 kg/m³, estimate the retention time.

The following data on the substrate removal rate and the substrate concentration is available for wastewater treatment (S) mol Rate, r (mol/min) 0.04 0.57 0.06 1.05 0.8 2.32 0.10 3.00 0.12 4.68 0.14 5.42 2.0 5.78 Estimate the value of substrate removal constant Km and the value of Vmax

1. The following information is provided for an activated sludge system design: Parameter Symbol Value Units Flow rate Q 10000 m³/d Influent BOD So 150 mg/L Effluent BOD S 2 mg/L Hydraulic residence time Ꮎ 4 hr Mean cell residence time Oc 6 d Maximum specific growth rate μm 3 1/d Half saturation constant Ks 40 mg/L Yield coefficient Y 0.5 Endogenous decay coefficient b 0.08 1/d Death rate coefficient γ 0.04 1/d Determine: a) The aeration tank biomass concentration (X) in mg/L b) The aeration tank oxygen requirement in kg/d c) The rate of biomass wasting in kg/d