n-Butanol Production from Engineered Cyanobacteria Abhivir Sandhu, Amir Meysami, Bowen Liu, Bryce Difley, David Gurr, Marc Caruth, Michael Chang, Sarah Rajani CHBE 453 : Bio Group 3 FLUE GAS Production Goal: 100 million gallons/year n-butanol at 98% purity Plant Design Environmental Impact Economics ABSORPTION CELL GROWTH PRODUCTION NAOH AIR WATER WATER TREATMENT PRODUCT SEPARATION N-BUTANOL Absorption Column NaOH + CO 2 —> HCO 3 - + Na + CO2 is converted to HCO 3 - to prevent the need for sparging. Carbon Source 8 % CO 2 flue gas from a natural gas power plant has low concentrations of growth limiting SO X and NO X . Photobioreactors 8HCO 3 - + H 2 O —> 4CO 3 2 - +C 4 H 9 OH + 6O 2 A common drawback of photobioreactors is the inability to deal with excess O 2 production. Integrated degassers allow for O 2 and n-butanol removal to prevent product inhibition. The gas is collected to recover the stripped n-butanol. Bubble Column Compressed air separates n-butanol while eliminating the need to remove cells from culture broth. Pervaporator Water/n-butanol forms an azeotrope. Pervaporation reduces the separation equipment required compared to ordinary distillation Recycle Cells are concentrated through centrifugation and sent back to the production photobioreactors. A purge stream prevents build-up of toxins. Objectives Motivation: Since 1990, CO 2 emissions from fossil fuels have increased by 60%, greatly affecting the air quality. Cyanobacteria are unicellular organisms that fix CO 2 and light to produce carbohydrates. In collaboration with Phytonix, we have developed an indus- trial process that produces n-butanol us- ing their engineered strain. PURGE Market Outlook: The current global demand of n-butanol is estimated at 8 billion USD and projected to reach 10 billion USD by 2020. Butanol can be used as an intermediate for a variety of chemicals, a solvent or fuel. Economic Comparison: Equipment expenses for start-up are comparable to other methods of production. Although ABE fermentation requires a smaller initial investment, separation costs exceed the initial savings. Raw material cost for petro-chemical catalysis fluctuates heavily with propylene costs. Annual Operating Expenses Start-up Cost by Production Method Global Butanol Demand Current Established Regulations: There are currently no emission regulations designated by the EPA for n-butanol. Existing Regulations: Ontario Air Emission: 920 µg/m 3 for a 24 hour emission average New York State Water Quality Level: 50 µg/L Preparing for Regulations: n-Butanol emission testing from the absorption column will be implemented. Treatment ponds for n-butanol removal from liquid waste and cell settling for sludge removal will be constructed. Possible sludge treatment applications include fertilizers or biogas production. EPA n-Butanol Emission Regulation 1 2 3 4 5 Draft Development July 1991 Agency Review Science Consultation June 2011 External Review August 2011 Revise Assessment (yet to begin) Flammable Level Control LC Liquid Hammer Concentration Hazard Assessment $141.2 million USD/year