Syngas fermentation to biofuel: Syngas fermentation to biofuel: Evaluation of carbon monoxide mass Evaluation of carbon monoxide mass

transfertransferand analytical modeling using a and analytical modeling using a

composite hollow fiber (CHF) membrane composite hollow fiber (CHF) membrane bioreactorbioreactor

SyngasSyngas

Synthesis gasSynthesis gas– Produced from the gasification of Produced from the gasification of

carbon-rich feedstockcarbon-rich feedstock– Composed primarily of carbon monoxide Composed primarily of carbon monoxide

and hydrogenand hydrogen– Can be converted to biofuelsCan be converted to biofuels

ProblemsProblems

Syngas exists in a gaseous phaseSyngas exists in a gaseous phase Microorganisms are in an aqueous Microorganisms are in an aqueous

phasephase

Mass Transfer ImplicationsMass Transfer Implications

Mass transfers occurs at several points:Mass transfers occurs at several points:– transfer of gas to gas-liquid interfacetransfer of gas to gas-liquid interface– transfer of gas to liquidtransfer of gas to liquid– transfer of gas to liquid around transfer of gas to liquid around

microorganismmicroorganism– diffusion of gas into microorganismdiffusion of gas into microorganism

Solubility of CO and HSolubility of CO and H22 are low are low Gas–liquid mass transfer is a rate-Gas–liquid mass transfer is a rate-

limiting step in syngas fermentationlimiting step in syngas fermentation

Previous Bioreactor DesignsPrevious Bioreactor Designs In order to increase mass transferIn order to increase mass transfer

– Increase pressureIncrease pressure– Increase gas-liquid surface areaIncrease gas-liquid surface area– Increase agitationIncrease agitation– Alternative designsAlternative designs

This studyThis study

Determine the mass transfer Determine the mass transfer efficiencies of carbon monoxide in efficiencies of carbon monoxide in composite hollow fiber (CHF) composite hollow fiber (CHF) membrane bioreactormembrane bioreactor

SetupSetup

CHF membrane bioreactor (3 liters)CHF membrane bioreactor (3 liters) Tap water (25°C)Tap water (25°C) Pure carbon monoxidePure carbon monoxide

CHF Membrane ModuleCHF Membrane Module

Pressurized gas is forced through one Pressurized gas is forced through one sideside

Gas can pass through a nonporus Gas can pass through a nonporus layerlayer

Liquid cannotLiquid cannot

ExperimentExperiment

Measure volumetric mass transfer Measure volumetric mass transfer coefficient at varyingcoefficient at varying– Water recirculation rates (five)Water recirculation rates (five)– Inlet carbon monoxide pressures (six)Inlet carbon monoxide pressures (six)

Carbon Monoxide Carbon Monoxide DeterminationDetermination

Myoglobin (Mb)-protein bioassayMyoglobin (Mb)-protein bioassay

ResultsResults

Compared with other Compared with other BioreactorsBioreactors

Resistance AnalysisResistance Analysis

ModelModel

Used data to create a modeling Used data to create a modeling equation using fluid dynamicsequation using fluid dynamics

DiscussionDiscussion

Demonstrated the effectiveness of Demonstrated the effectiveness of CHF membrane reactorCHF membrane reactor

ProblemsProblems

Did not compare bioreactors Did not compare bioreactors consistentlyconsistently

Did not test with syngasDid not test with syngas Did not test the affect on Did not test the affect on

microorganismmicroorganism

ReferencesReferences

Cussler, E. L. (2009). Diffusion, mass transfer in fluid Cussler, E. L. (2009). Diffusion, mass transfer in fluid systems. (3rd ed. ed.). Cambridge: Cambridge Univ Pr.systems. (3rd ed. ed.). Cambridge: Cambridge Univ Pr.

Munasinghe, P. C., & Khanal, S. K. (2010). Biomass-derived Munasinghe, P. C., & Khanal, S. K. (2010). Biomass-derived syngas fermentation into biofuels: Opportunities and syngas fermentation into biofuels: Opportunities and challenges. challenges. Bioresource technologyBioresource technology, 101(13), 5013-5022., 101(13), 5013-5022.

Munasinghe, P. C., & Khanal, S. K. (2012). Syngas Munasinghe, P. C., & Khanal, S. K. (2012). Syngas fermentation to biofuel: Evaluation of carbon monoxide fermentation to biofuel: Evaluation of carbon monoxide mass transfer and analytical modeling using a composite mass transfer and analytical modeling using a composite hollow fiber (CHF) membrane bioreactor. hollow fiber (CHF) membrane bioreactor. Bioresource Bioresource TechnologyTechnology, 112, 130-136, 112, 130-136

Riggs, S. S., & Heindel, T. J. (2008). Measuring Carbon Riggs, S. S., & Heindel, T. J. (2008). Measuring Carbon Monoxide Gas—Liquid Mass Transfer in a Stirred Tank Monoxide Gas—Liquid Mass Transfer in a Stirred Tank Reactor for Syngas Fermentation. Reactor for Syngas Fermentation. Biotechnology progressBiotechnology progress, , 22(3), 903-906.22(3), 903-906.