Question 1 - Compare the cell concentration that will be present after 24 h through batch growth on a non-growth limiting concentration of acetate for the following four cases, assuming that Y is the only variable between the organisms. The initial cell concentration in all cases is 10 mg/l. Assume other constants of interest are q^ = 12 mg acetate/mg VSSa-d, K = 2 mg/l, and b = 0.1/d.
(a) Y = 0.6 mg VSSa/mg acetate (aerobic growth)
(b) Y = 0.45 mg VSSa/mg acetate (denitrification)
(c) Y = 0.06 mg VSSa/mg acetate (sulfate reduction)
(d) Y = 0.04 VSSa/mg acetate (methane fermentation)
Question 2 - A CSTR reactor is used for treatment of 50 m3/d of wastewater with CODb of 10,000 mg/l by methane fermentation. Assume Y = 0.04 mg VSSa/mg BODL, q^ = 8 mg BODL/per VSSa-d, K = 200 mgBODL/l, and b = 0.05/d.
What reactor detention time will result in the maximum BODL removal per day per unit volume of reactor? (You may find it useful to use a spreadsheet or programmable calculator, as a trial and error solution is likely to be needed). Show a graph of BODL removal per day per unit reactor volume versus reactor detention time.