Syngas fermentation to biofuel: Evaluation of
carbon monoxide mass transfer
and analytical modeling using a composite
hollow fiber (CHF) membrane bioreactor
Syngas

Synthesis gas
– Produced from the gasification of carbon-rich
feedstock
– Composed primarily of carbon monoxide and
hydrogen
– Can be converted to biofuels
Problems
Syngas exists in a gaseous phase
 Microorganisms are in an aqueous phase

Mass Transfer Implications

Mass transfers occurs at several points:
– transfer of gas to gas-liquid interface
– transfer of gas to liquid
– transfer of gas to liquid around microorganism
– diffusion of gas into microorganism
Solubility of CO and H2 are low
 Gas–liquid mass transfer is a rate-limiting
step in syngas fermentation

Previous Bioreactor Designs

In order to increase mass transfer
– Increase pressure
– Increase gas-liquid surface area
– Increase agitation
– Alternative designs
This study

Determine the mass transfer efficiencies of
carbon monoxide in composite hollow
fiber (CHF) membrane bioreactor
Setup
CHF membrane bioreactor (3 liters)
 Tap water (25°C)
 Pure carbon monoxide

CHF Membrane Module
Pressurized gas is forced through one side
 Gas can pass through a nonporus layer
 Liquid cannot

Experiment

Measure volumetric mass transfer
coefficient at varying
– Water recirculation rates (five)
– Inlet carbon monoxide pressures (six)
Carbon Monoxide Determination

Myoglobin (Mb)-protein bioassay
Results
Compared with other Bioreactors
Resistance Analysis
Model

Used data to create a modeling equation
using fluid dynamics
Discussion

Demonstrated the effectiveness of CHF
membrane reactor
Problems
Did not compare bioreactors consistently
 Did not test with syngas
 Did not test the affect on microorganism

References




Cussler, E. L. (2009). Diffusion, mass transfer in fluid systems. (3rd
ed. ed.). Cambridge: Cambridge Univ Pr.
Munasinghe, P. C., & Khanal, S. K. (2010). Biomass-derived syngas
fermentation into biofuels: Opportunities and challenges.
Bioresource technology, 101(13), 5013-5022.
Munasinghe, P. C., & Khanal, S. K. (2012). Syngas fermentation to
biofuel: Evaluation of carbon monoxide mass transfer and analytical
modeling using a composite hollow fiber (CHF) membrane
bioreactor. Bioresource Technology, 112, 130-136
Riggs, S. S., & Heindel, T. J. (2008). Measuring Carbon Monoxide
Gas—Liquid Mass Transfer in a Stirred Tank Reactor for Syngas
Fermentation. Biotechnology progress, 22(3), 903-906.