ALS 331 Problem Set 5 Due 2:30pm Wednesday Oct 26 2011

ALS 331 Problem Set 5 Due 2:30pm Wednesday Oct 26 2011 1. Anaerobic digestion of volatile acids by methane bacteria is represented by the equation: CH3COOH + NH3 biomass + CO2 + H2O + CH4 The composition of methane bacteria is approximated by the empirical formula CH1.4O0.4N0.2. For each kg acetic acid consumed 0.5 kg CO2 is evolved. How does the yield of methane under these conditions compare with the maximum possible yield? (10 points) 2. The thermophilic methanogen Methanococcus jannaschii metabolizes hydrogen and carbon dioxide gas to produce gaseous methane (CH4) and water. Gas consisting of 60.0% H2 20.0% O2 and 20.0% CO2 is fed at a flow rate of 100.0 mol/min into a bioreactor containing M. jannaschii. (10 points) (a) Write out the balanced chemical reaction for methane production by M. jannaschii. (b) What is the limiting reactant (show work)? (c) Determine the extent of reaction if 10.0% of the hydrogen fed into the reactor exits in the product unreacted. (d) For the conditions given in (c) determine the mole fraction of CH4 in the product. (e) What is the % yield of CH4 (based on theoretical consumption of the limiting reactant)? 3. Problem 4.6 in Doran book. (10 points) 4. (Bonus) A feed stream containing glucose enters a fed-batch fermenter at constant flow rate F. The initial volume of liquid in the fermenter is V0. Cells in the fermenter consume glucose at a rate given by r = kcA where k is the rate constant and cA is the concentration of glucose in the fermenter. Assuming constant density write out equations (without solving) for (a)Total mass balance (b) Glucose mass balance. (5 points total)
Attachments: