Bioconversion of paper mill waste to value-added chemicals

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Bioconversion of paper mill waste TAPPI EPE Conference 2009

October 14, 2009, Biorefinery, TAPPI EPE Conference

Bioconversion of paper mill waste to value-added chemicals

Achira Mukhopadhyay, Praveen Vadlani,BIVAP, Kansas State University, Manhattan, KS

Ravi Mulukutla and Fred Renk, Center for Packaging Innovation, MeadWestvaco MWV, Raleigh, NC

A global leader in A global leader in endend--toto--end packaging end packaging solutionssolutions

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OutlineOutline

Biorefinery Lactic acid platform

Bioconversion of paper mill sludgeHydrolysis - Enzymatic Fermentation - Bacterial / Fungal / Proprietary culturesResponse Surface Methodology (RSM)FTIR characterization

Future workConclusion

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BiorefineryBiorefinery

Source: DOE

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Bioconversion of paper mill waste TAPPI EPE Conference 2009 4



Top Value Added Chemicals from Biomass (2004 DOE report)

Lactic acidLactic acid

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Lactic acid platformLactic acid platform

Lactic acidLactic acid

PLAPLA

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Bioconversion of paper mill waste TAPPI EPE Conference 2009 7

Lactic acid based biopolymers are biodegradable and are being increasingly used in food produce packagingUsed as a precursor for polylactide, which is used in tissue engineering materialsWidely used additive in the food industryUsed to manufacture environmental friendly solvents

Lactic acid usesLactic acid uses



Paper mill sludgePaper sludge:

Principle solid waste from paper-making industry. Chemically modified wood fibers

Additives:Major- clay, calcium carbonate, starchMinor- sulphur, anthroquinone, barium sulphate.

Present use:Burned or disposed in landfills.

Aim of the study:Production of lactic acid from paper sludge.

Benefits:Easier waste disposal.Production of value added material

Paper mill sludge

Components Concentration (%w/w)

Cellulose 21.1 ± 1.4

Hemicellulose 4.1 ± 0.3

Lignin 13.9 ± 0.6

Ash 48.5 ± 1.2

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Pathway to lactic acidPathway to lactic acid

Current workCurrent work

HydrolysisHydrolysis FermentationFermentation

CelluloseATCC &

Proprietary Proprietary cultures

Novozymes

(optimized)SugarPulp/Sludge Lactic acid

cultures

S S FS S F

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State of the art : Objectives : ApproachState of the art : Objectives : Approach

State of the art:Enzyme loading determined [Lee et al, 2004; Romani et al., 2007]Fermentation of sludge using Lactobacillus Sp. [Marques et al., 2008; Nakasaki et al., 2007]

ObjectivesDevelop a model to determine lactic acid production as a function of Cellulase enzyme loading when operating as SSF and FermentationStudy the differences in hydrolysis pattern of pure paper pulp and paper mill sludge to get higher yields of sugarUse of Rhizopus oryzae for fermentation and compare with it’s performance to Lactobacillus sp.

ApproachHydrolysis of cellulosic component followed by fermentation to lactic acid

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Effect of Effect of ββ--glucosidase supplementation on paper pulp hydrolysisglucosidase supplementation on paper pulp hydrolysis(Shake Flask)(Shake Flask)

Time(h)

0 5 10 15 20 25 30 35

Glu

cose

rele

ase(

g/g

cellu

lose

)

0.0

0.2

0.4

0.6

0.8

1.0

lowmediumhigh

Time (h)

0 5 10 15 20 25 30 35

Glu

cose

rele

ase

( g/g

cel

lulo

se)

0.0

0.2

0.4

0.6

0.8

1.0

lowmediumhigh

Without β-glucosidase With β-glucosidase

β-glucosidase supplemented at X µl/g of celluloseMore pronounced effect at the early stagesResidual cellobiose accumulation

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Effect of Effect of ββ--glucosidase supplementation on sludge hydrolysis.glucosidase supplementation on sludge hydrolysis.

Time( h)

0 5 10 15 20 25 30 35

Glu

cose

rele

ase(

mg/

mg

cellu

lose

)

0.0

0.2

0.4

0.6

0.8

1.0

nillowmediumhigh

.β-glucosidase supplemented with cellulaseVery low hydrolysis rate observed without β-glucosidaseβ-glucosidase inactivation occurs due to adsorption on ash and

lignin (Zheng et al 2007)

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Response surface methodology-A statistical optimization tool

Response surface methodology (RSM) searches for the input combination that optimizes the simulation outputExplores the relationship between several explanatory variables and one or more response variablesIt estimates the main effects, interaction effects and quadratic effects of the explanatory variables, and based on this, generates the shape of the response surface under investigationFinally, using this response surface, the software identifies the optimum point where all specifications can be met at a minimal cost.

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Model building using RSMModel building using RSM

Data generated using one-factor at a time method used to set up a simultaneous saccharification and fermentation experiment in a central composite designAllows for more thorough navigation of the effective design space and identify the optimum combination of enzymes for hydrolysis.Explanatory variables- Enzymes (µl/g cellulose) , β-glucosidase, and temperatureProvide lower and upper limits of dosageReduction of ~20% enzyme dosage was observed

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FTIR spectroscopyFTIR spectroscopy

To investigate the components responsible for adsorbing β-glucosidase.Changes in spectra expected if binding occurred, either electrostatically or covalently.Principle components - pulp, lignin, calcium carbonate and clay separated,Each of these incubated with equal amounts of enzyme at 45 °C for 24 hrs.Centrifuged thrice to remove unbound enzyme.Spectra recorded for isolated components with and without enzyme.

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Results of FTIR spectroscopyResults of FTIR spectroscopy

Lignin adsorbs enzyme by ionic interactions, H bonds.(Peak broadening and shift towards lower wave number.)

Clay adsorbs enzyme by covalent interactions.(Disappearance of silane stretch peak.)

Pulp shows no enzyme immobilization (No change in spectra.)

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Further investigationsFurther investigationsFurther investigations

Quantitative determination of the amount of enzymes adsorbed by clay and ligninImprovement of fungal yield and productivity by strategies such as changing media composition, fermentation conditions etc.Identification of compounds inhibiting bacterial growthDevelopment of a fed-batch schedule for increasing the glucose concentration and finally the lactic acid yield

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ConclusionConclusionConclusion

Successfully demonstrated production of value added chemicals like lactic acid from under-utilized renewable resources (paper mill sludge) via hydrolysis and microbial fermentationThe work involved the advances in bio-catalysis and the availability of improved and robust microbial strains, which has high potential for economical process to produce chemicals, such as lactic acid, from woody biomassThe constituents of the paper mill wastes are important and presence of lignin and other inorganic ash may have a detrimental effect on enzyme kinetics and microbial fermentation. Suitable means to isolate these constituents from the feedstock should be identified to enable high productivity.

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Thank you …..Questions ???

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Bioconversion of paper mill waste to value-added chemicals

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