Question

6.8 a. Using the variable-order kinetic information from Example 6.8 for a municipal wastewater, determine the effluent BODs concentration for a complete-mix activated sludge facility operated at a five-day solids residence time. b. For a wastewater flow rate of 2 million gallons per day with character- istics of a typical wastewater from Table 6.1, determine the discharge rate of biomass (Ibs/day). in the lagooll lall x biomass Rearranging Eq.(6.37) V X HRT EXAMPLE 6.8 Determine the required volume of an aerated lagoon treatment of municipal wastewater to achieve compliance with an effluent BO of 12 mg/L. Lab studies have shown that Ymax 0.65 mg biomass/s standard k, -0.06 days1, k 1.5 mg BODs/mg biomass-day, and Ks 80 mg/L BOD. Assume that an aerated lagoon may be described as a completely mixed reac. tor without solids separation and recycle. a 5.0 MGD SOLUTİONic substrate utiliza 1 X12 0.196 ngbiom The specific substrate utilization is kS Ks +S 1.5×12 q= (80+12) 0.196-m8BOD5 ks +s-(80-12) mg biomass-day The required growth rate for the specified kinetics is: μ-Ymax (9)-ke-0.65x 0.196-0.06 H 0.0674 days-1 But HRT = 1/u, so the required hydraulic residence time is 14.8 days. Finally, the volume of the lagoon is HRT x Q: v-14.8 days × 5.0 MGD = 74 million gallons The next example deals with a specialized waste, one that contain dis one easily biodegraded compound. It illustrates a point that we only cussed yet, and that is the need for nutrients. Bacteria are living creaxa need not only food (the BOD) but also nutrients like N and P. In thtsbe vae ple, no nitrogen compounds are present. A source of nitrog to support biomass cell synthesis, so we must a be used by bacteria) to achieve successful biological treatmei wastewaters almost always have enough nutrients; however wastewaters, particularly high-carbohydrate food-processing tures next exam- en must be av t. Municipal indusn (in a form that can rtain ind

Answer 1