Baeta-Hall, Lina

Duarte, José  Cardoso

Lourenço, Vera

Ribeiro, Belina

Sàágua, Mª do Céu

English

Engineering Conferences International

1Bioenergy-I: From Concept to Commercial ProcessesCONTINUOUS CULTURE OF FLOCCULENT YEAST FOR ETHANOL PRODUCTIONJosé Cardoso DuarteVera Lourenço, Belina Ribeiro, Mª do Céu Sàágua, Lina Baeta-HallINETI Instituto Nacional de Engenharia, Tecnologia e InovaçãoBiotechnology DepartmentPortugal5-10 March 2006EU Project FERMATEC, ENK5/CT/2002/30029.Tomar, Portugal2Tomar, 5-10 March 2006?Brief IntroductionBioethanol production became an important issue because:?EU has established that 5.75% of transport fuels must beobtained from renewable sources (such as bioethanol) till 2010;?Bioethanol production is a well known and developedtechnology but gains in productivity are still possible;?The interest for the use of new raw materials (lignocellulosicbased) was raised by the recent oil crisis. Bioenergy-I: From Concept to Commercial Processes3How to increase productivity of the bioethanolproduction process? rP=P. D=Y . X . DPossible strategies: 1. use of high concentration of active microorganisms in the bioreactor.2. increase of dilution rate.Bioenergy-I: From Concept to Commercial ProcessesTomar, 5-10 March 20064How to increase concentration of active microorganisms inthe bioreactor??By cells immobilisation;?By natural settling techniques?using cells flocculation ability. Bioreactors using cells flocculation techniques couldpresent some advantages:?Low associated capital and operational costs;?Design simplicity.Answer: many yeast and Zymomonas strains have goodflocculation ability.Bioenergy-I: From Concept to Commercial ProcessesTomar, 5-10 March 20065190*Recycled Cells50-170Free CellsFluidized Bed Reactor16-40Packed Bed Reactor10-30Entrapm. by Membranes10-16Immobilized Cells6-8Free CellsContinuous Stirred Tank Reactor2-5Batch and Fed-BatchrP (gEtOH/L h)Bioreactor Configuration* Productivity achieved at D=2,5 h-1.?The importance of Bioreactor ConfigurationBioenergy-I: From Concept to Commercial ProcessesTomar, 5-10 March 20066?The Fluidized Bed Reactor (FBR) ?with Flocculated Cells RecyclingFeedPumpFeedEffluentRefrigeratingWater InRefrigeratingWater OutSamplePortRecirculationPumpSamplePortGasBioenergy-I: From Concept to Commercial ProcessesTomar, 5-10 March 20067?Strain Selection and Batch Tests•S. cerevisiae strainsCCMI 396DER 24DSMZ 2548NCYC 1119F•Relevant parameters-Maximum specific growth rate (μm)-Ethanol yield (YP/S)-Ethanol toleranceBioenergy-I: From Concept to Commercial ProcessesTomar, 5-10 March 20068?Strain Selection and Batch TestsStrainμm(h-1)Xf(g/L)Pf(g/L)YP/S(g/g)<rP> (g/Lh)CCMI 396 0.366 9.87 31.50 0.26 1.31DER 240.366 11.08 41.50 0.35 1.73DSMZ 2548 0.396 13.60 46.60 0.23 1.94NCYC 1119 0.440 nd 49.59 0.39 2.07F 0.490 12.73 43.50 0.40 1.81Substrate: sucrose 120 g/LTemperature: 28ºCBioenergy-I: From Concept to Commercial ProcessesTomar, 5-10 March 20069?Strain Selection and Batch Tests0,00,20,40,60 5 10 15 20Ethanol Concentration (%) Growth rate (h-1)2548 396 1119 Fall strains showed good tolerance to ethanol.Batch Conditions:-Ethanol addition in concentrations ranging from 0 to 20%-Initial sucrose: 120 g/L-Temperature: 28ºC-Shake flasksBioenergy-I: From Concept to Commercial ProcessesTomar, 5-10 March 200610?Strain Selection and Batch TestsGrowth in Cane Molasses01020304050600 24 48Time (h)CFU * 107396 2548 1119 Fstrain F showed a better performance ingrowing in cane molasses medium. Strain1119 cell concentration is the lowest butthat is due to the high sedimentation velocity, which difficults a representative sampling.Batch Conditions:-Initial sugar: 120 g/L-Temperature: 28ºC-Shake flasksBioenergy-I: From Concept to Commercial ProcessesTomar, 5-10 March 200611?Strain Selection and Batch Tests:Only strains F and 1119 showed good flocculationability, which is very important in FBR fermentationswith no solid suport to retain biomass;1119 has more dense flocs than F.Due to higher maximum specific growth rates, ethanol yields and flocculation ability, strains F and1119 are suitable for ethanol production in FBRBioenergy-I: From Concept to Commercial ProcessesTomar, 5-10 March 200612?Continuous FBR Tests: Strain F-Defined sucrose media-Temperature: 28ºC20304050607080901000 200 400 600 800 1000Time  (h)Sc (%), P (g/L)0,00,10,20,30,40,5D (h-1)So=100 g/L So=120 g/LScPBioenergy-I: From Concept to Commercial ProcessesTomar, 5-10 March 200613?Continuous FBR Tests: Strain F0510152025300 200 400 600 800 1000Time (h)X (g/L)0,00,10,20,30,40,5D (h-1)So=100 g/L So=120 g/LXRXoThere is a good capacity for retention of biomassBioenergy-I: From Concept to Commercial ProcessesTomar, 5-10 March 20061401020304050600 200 400 600 800 1000Time  (h)rP,rS (g/Lh)0,00,10,20,30,40,5D (h-1)So =100 g /L So =120 g /LrSrPYP/S=0.47XR≈25 g/LXo <5 g/L?Continuous FBR Tests: Strain FD=0.4 h-1Sc=90%P=50.8 g/LrP=20.3 g/LhBioenergy-I: From Concept to Commercial ProcessesTomar, 5-10 March 2006150,00,10,20,30,40,50 200 400 600 800 1000Time (h)D (h-1)YX/S, YP/SSo=100 g/L So=120 g/LYX/SYP/SHandicap?: Strain F formssmall flocs with lowsedimentation velocity.?Continuous FBR Tests: Strain FBioenergy-I: From Concept to Commercial ProcessesTomar, 5-10 March 200616Studying reactors with high flocculated cells concentrationin real time is not easy to accomplish:?Unsteady regimes develop often?Biomass viability and production yield may change quickly.Strategy: Construction of an inferential sensor to estimatebiomass, based on other properties of the systems easier to monitor in real time (such as nutrients and productsconcentrations, operational conditions, etc).Practical problem:How to measure in real time biomass concentration insidethe reactor to monitor steady states?Bioenergy-I: From Concept to Commercial ProcessesTomar, 5-10 March 200617?Construction of a biomass inferential sensor:?For statistical fitting of data, only steady-state valueswere used concerning experiments with strain F.?Biomass concentration within the broth was related to ethanol, biomass concentration in the outflow, dilution rate and percentage of consumed sugar. ?Only linear correlations were tested and the best one wasobtained through an Ordinary Linear Square (OLS) Regression.Bioenergy-I: From Concept to Commercial ProcessesTomar, 5-10 March 200618?Construction of a biomass inferential sensor:XR = 37.64 D + 0.35 Sc + 0.08 Xo + 0.42 P – 46.54XR, Xo and P are expressed as g/L;Sc is expressed as %0510152025300 5 10 15 20 25 30XR exp (g/L)XR mod (g/L)Bioenergy-I: From Concept to Commercial ProcessesTomar, 5-10 March 200619?Construction of a biomass inferential sensor:?The constructed biomass inferential sensor permits to predictbiomass concentration within the bioreactor by the quickermeasurement of other variables.?The correlation fitted well the used data, expressed by the RootMean Square Error (RMSQ=0.68). ?The correlation is capable of predicting biomass concentration ina quite reasonable way, as the R2cv parameter expresses (R2cv=0.67).?The most important predictor is dilution rate (37.64) and theleast important is biomass concentration in the outflow (0.08).Bioenergy-I: From Concept to Commercial ProcessesTomar, 5-10 March 200620?Continuous FBR Tests: Strain 1119Strain 1119 has bigger flocsand higher sedimentationvelocity, which allows it to stayinside the FBR at higherdilution rates (D>μm).At all testeddilution rates cellsalways showedviability ab-ove90%.0204060801001201400,20 0,40 0,60 0,80 1,00 1,20D (h-1)XR (g/L)Bioenergy-I: From Concept to Commercial ProcessesTomar, 5-10 March 200621?Continuous FBR Tests: Strain 1119Ethanol productivity of more than 15 g/Lh was attained, but theyield YS/P was of 0.2 (aprox.). If we can raise YS/P till near thetheoretical one (0.5) ethanol productivity will be near to 40 g/Lh.  051015202530350,00 0,20 0,40 0,60 0,80 1,00 1,20D (h-1)S (g/L)05101520rP (g/Lh)S rP Linear (S) Linear (rP)Bioenergy-I: From Concept to Commercial ProcessesTomar, 5-10 March 200622?Continuous FBR Tests: Strain 1119?Some pictures of FBR in operationStrain F Strain 1119Bioenergy-I: From Concept to Commercial ProcessesTomar, 5-10 March 200623?Continuous FBR Tests: Microbial ResistanceFBR showed a natural resistance concerning microbial contamination, mainly due to:?high dilution rates?high cells densityThis means:?longer fermentations?reduced need for sterilityBioenergy-I: From Concept to Commercial ProcessesTomar, 5-10 March 200624?Continuous FBR Tests: Scale-UpPrototypes (4;25;400;4000 L ) werebuilt and tested for long-term operationwith good results.25L-prototype: a tubular air-liftreactor with an external settler; Bioenergy-I: From Concept to Commercial ProcessesTomar, 5-10 March 200625Bioenergy-I: From Concept to Commercial ProcessesThank you for your attention!For any enquiries email me:jose.duarte@ineti.ptTomar, 5-10 March 2006

Continuous Culture of Flocculent Yeast for Ethanol Production: Physiology, Productivity and Modeling

https://dc.engconfintl.org/cgi/viewcontent.cgi?article=1004&amp;context=bioenergy_i

Continuous Culture of Flocculent Yeast for Ethanol Production: Physiology, Productivity and Modeling

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