Ethanol Production from the Mixture of Hemicellulose Prehydrolysate and Paper Sludge Li Kang, David Webster, Harry Cullinan and Y. Y. Lee Department of Chemical Engineering Auburn University 1
Outline 1. Introduction 2. Pre-extraction process 3. De-toxification of pre-hydrolysate 4. Separation hydrolysis and fermentation (SHF) of pre-hydrolysate 5. Increasing the ethanol concentration a. concentrated pre-hydrolysate b. mixing pre-hydrolysate with paper sludge 6. Conclusion 2
Current Kraft pulping process Other 5-15% Lignin 15-25% Cellulose 38-50% Hemicelluloses 23-32% Black Liquor : 80% of hemicelluloses and lignin Heating Value: Hemicellulose (13.6 MJ/kg) Lignin (27 MJ/kg). 3
Proposed Kraft pulping process 4
2. Pre-extraction Process Fresh Pine Wood Chip Water 500-mL Cylindrical Batch (bomb) Digesters Extracted Wood Chip Pre-hydrolysate Liquor/wood = 5.8 / 1, 170 C M/K Laboratory Digester 5 Sung-Hoon BioPro Expo Yoon, & Marketplace al., Ind. Eng. / Atlanta, Chem. Res., GA / 2010, March 49 14-16, (13), 5969 5976 2011
The profile of weight, hemicellulose and cellulose loss versus extraction time Weight Loss, Hemicellulose Loss (%) 16.00% 14.00% 12.00% 10.00% 8.00% 6.00% 4.00% 2.00% 0.00% 0.04% 0.03% 0.03% 0.02% 0.02% 0.01% 0.01% 0.00% 0 20 40 60 80 100 Time (min) Weight Loss Hemicellulose Loss Cellulose Loss Cellulose Loss (%) Cellulose 162 Mannose 162 = Glu cose*( ) *( ) 180 4.15 180 Hemicellulose 132 162 = ( Arabinose + Xylose)*( ) + ( Galactose + Glu cose + Mannose)*( ) Cellulose 150 180 6 Yoon, BioPro S. Expo H. and & van Marketplace Heiningen, A. / Atlanta,, Journal GA of Industrial / March and 14-16, Engineering 2011 Chemistry,16 (1), 74-80, 2010
Composition of pre-hydrolysate Sugars Concentration (g/l) Other Compounds (g/l) 10.0 9.0 8.0 7.0 6.0 5.0 4.0 3.0 2.0 1.0 0.0 0.8 0.7 0.6 0.5 0.4 0.3 0.2 0.1 0.0 Man2, 9.1 Glu2, 1.4 Xyl2, 2.4 Gal2, 2.1 Ara, 1.4 Xyl, 1.1 Glu, 0.4 Gal, 0.7 Man, 0.6 Ara2, 0.1 0.8 0.4 0.3 0.2 0.1 Acetic acid Acetyl group Levulinic acid HMF Furfural 7
Three stage pre-extraction process Fresh Wood Chip Water Fresh Wood Chip Make-up Water Fresh Wood Chip Make-up Water First Stage I Second Stage II Third Stage III First Stage Pre-hydrolysate I Second Stage Pre-hydrolysate II Third Stage Pre-hydrolysate III Extracted Wood Chip Extracted Wood Chip Extracted Wood Chip Fresh Wood Chip Pre-hydrolysate Screw Reactor Extracted Wood Chip Water 8
Sugars Concentration (g/l) Other Compounds (g/l) 18.0 16.0 14.0 12.0 10.0 8.0 6.0 4.0 2.0 0.0 3.0 2.5 2.0 1.5 1.0 0.5 0.0 Composition of pre-hydrolysate III after three-stage pre-extraction Glu2, 3.0 Xyl, 1.1 Gal2, 3.9 Glu, 0.4 Xyl2, 2.7 Gal, 0.7 Ara, 1.4 Man2, 15.5 Man, 0.6 Ara2, 0.1 2.6 1.4 1.0 0.5 0.2 Acetic acid Acetyl group Levulinic acid HMF Furfural 9
3. De-toxification of Pre-hydrolysate Average composition of Woody biomass and main derived hydrolysis products J.R.M. Almeida, T. Modig, A. Petersson, B. Hahn-Hägerdal, G. Liden and M.F. Gorwa- Grauslund, J Chem Technol Biotechnol 82 (4) (2007), pp. 340 349 10
De-toxification test Overliming: Pre-hydrolysate III was added CaO to ph=10.0, 25 C or 60 C for half hour, centrifuge, then adjust supernatant ph to 5.0 by adding 70% sulfuric acid. UV-Vis Absorbance Changed During De-toxification Test Absorbance 3.2 2.8 2.4 2.0 1.6 1.2 0.8 0.4 0.0 untreated 25 C 60 C 200 250 300 350 400 450 wavelength (nm) Vanillin(230nm) Furfural(278nm) HMF(284nm) p-coumaric acid (308nm) Ferulic Acid (322nm) 4-hydroxyacetophenone (340nm) 11
Composition change after de-toxification test % 100 80 60 40 20 0 Total Sugar Mannose + Glucose Acetic Acid Levulinic acid untreated 25 C 60 C HMF Furfural Total Soluble Phenolic 12
48h enzymatic digestibility/% 100% 80% 60% 40% 20% 0% 4. Separate hydrolysis and fermentation (SHF) of pre-hydrolysate Cellulase β-glucosidase Xylanase Pectinase Glucose Xylose Galactose Mannose Enzyme Loading: 25mg protein enzymes / g-mannose oligomer 50 C, ph=4.8 13
Fermentation of pre-hydrolysate III by Saccharomyces cerevisiae 5 16 Glucose Conc. (g/l) 4 3 2 1 0 untreated 60 C 25 C 0 20 40 60 80 100 Time (h) 12 Mannose Conc. (g/l) 14 12 10 8 6 4 2 0 untreated 60 C 25 C 0 20 40 60 80 100 Time (h) Ethanol Conc. (g/l) 10 8 6 4 2 0 untreated 60 C 25 C 0 20 40 60 80 100 Time (h) SHF condition Enzymatic Hydrolysis:: 25mg protein Pectinase/ g-mannose oligomer and 50 C. Fermentation Conditions : 32 C, Saccharomyces cerevisiae D5A 14
5. Increasing the ethanol concentration a. concentrated pre-hydrolysate Laboratory Scale: Rotary evaporator. -Total sugar concentration Increase. -Furfural and acetic acid are removed up to 90%. Industry Scale: Steam- Stripping or Flash Tank and Multiple-effect Evaporator (Kraft mill). 300 250 200 150 100 50 0 41 94 246 Total Sugars (g/l) 146 85 55 26 44 76 63 20 11 Glu+Mann (g/l) Ethanol Conc.(g/L) III IV (2.2 ) V (5.9 ) Yield (%) 15
b. mixing pre-hydrolysate with paper sludge Kraft Paper Mill Sludges as a Feedstock 4.1 to 5 million tons sludge per year in U.S. - Incineration (greenhouse gas emission, low energy efficiency) - Landfill (greenhouse gas emission, limited land availability) Low/ Negative Cost ( 0 to 50$ per ton disposal cost) High Carbohydrate and Low Lignin Content (Kraft pulping process removes most of lignin and hemicellulose) Easily Digested by Cellulase (No need for expensive pretreatment) 16
Composition of various sludges Primary Sludge is from Boise paper mill, Jackson, AL. Kang,L., Wang,W., Lee, Y.Y., 2010. Appl. Biochem. Biotechnol. 161(1-8), 53-66. 17
Fermentation of pre-hydrolysate III with paper sludge 35 90% 30 80% Ethanol Conc. (g/l) 25 20 15 10 5 0 Paper Sludge only Paper Sludge with Pre-hydrolysate Pre-hydrolysate only 0 24 48 72 96 120 Time (h) Ethanil Yield (%) 70% 60% 50% 40% 30% 20% 10% 0% Paper Sludge only Paper Sludge with Pre-hydrolysate Pre-hydrolysate only 0 24 48 72 96 120 Time (h) Maximum Ethanol Yield (%) Maximum Ethanol Conc. (g/l) Pre-hydrolysate III with paper sludge 71.5 (120h) 31.5 Pre-hydrolysate only 82.6 (48h) 10.3 Paper sludge only 73.4 (120h) 27.8 Enzyme Loading: Cellulase (15FPU/g glucan) + Cellobiase (30CBU/g glucan)+ 25mg protein Pectinase/ g-mannose oligomer Solid Loading:15 g total solid /100ml work volume SSF Conditions : 36 C, Saccharomyces cerevisiae D5A 18
Fermentation of pre-hydrolysate with de-ashed sludge Ethanol Conc. (g/l) 45 40 35 30 25 20 15 10 5 0 De-ashed sludge with pre-hydrolysate III De-ashed sludge only 0 24 48 72 96 120 Time (h) Ethanol Yield (%) 80% 70% 60% 50% 40% 30% 20% 10% 0% De-ashed sludge with pre-hydrolysate III De-ashed sludge only 0 24 48 72 96 120 Time (h) Maximum Ethanol Yield (%) Maximum Ethanol Conc. (g/l) Pre-hydrolysate III with de-ashed sludge 71.3 (120h) 40.1 De-ashed sludge only 75.2 (120h) 35.0 Enzyme Loading: Cellulase (15FPU/g glucan) + Cellobiase (30CBU/g glucan)+ 25mg protein Pectinase/ g-mannose oligomer Solid Loading:15 g total solid /100ml work volume SSF Conditions : 36 C, Saccharomyces cerevisiae D5A 19
Conclusion Combining pre-hydrolysate with sludge can more than double ethanol production Hemicellulose pre-hydrolysate can be converted to ethanol through de-toxification, enzymatic hydrolysis and fermentation processes. The fermentation of concentrated pre-hydrolysate can increase the ethanol concentration. The fermentation performance of the mixture of prehydrolysate with sludges has high efficiency and more practical. 20
Acknowledgments Vekanta Ramesh Pallapolu Urvi Kothari Suan Shi Allen Smith Sung-Hoon Yoon Gopal Krishnagopalan Alabama Center for Paper and Bioresource Engineering Boise Cascade, LLC Genencor International 21