Investigating and Modeling Natural Investigating and Modeling Natural Biodegradation System in Soil Biodegradation System in Soil

Mythreyi Chandoor, Deepak Singh and Shulin Chen

Bioprocessing and Bioproduct Engineering Laboratory, Department of Biological

Systems Engineering Washington State University .

Outline

•Aim and importance of the project• Background – Hypothesis of the project• Experimental:

MicrobiologyChemical analysis of lignocellulose degradation in soil.

• ModelingLignocellulose degradation in soilApplication

• Acknowledgements

Aim and importance of the project

•Demand for an Alternative Fuel The U.S. ethanol consumption is forecast to increase from 5.6 billion gallons last year to 13.5 billion gallons in 2012, (Thomson Reuters, 2009).

•What are the challenges ? One of the challenges lies in the deconstruction of lignin part of the biomass to release sugars.

Need for novel pretreatment technology !

Delignification, repolymerization

Humus formation

Proteins

Hypothesis: Lignocellulosic degradation system

in soil

Parallel degradation of cellulose and hemicellulose

Lignin –Major Linkages in the structure

OH

HO

HO

OOCH3- O- 4

4

o OH

OH

OH

4

-O-4

OH

OH

HO

HO

-

O

OH

5

5

5-5

O4-O-5

OR

-Hydroxyphenol

Lignin

OR

H3CO OCH3

Syringyl

Lignin

OR

OCH3

Guaiacyl

Lignin

O

OCH3O

R

OO

O

OXyl Xyl

HO

OO

HOO

O

O

O--H3CO OCH3

O

OXyl

HOOH

OHOOCH3

H3CO

o

O

HO

OCH3

OH

O

O

CH

CH

C O

O CH

CH2OH

COH

O CH

CH2OH

O

H3CO OCH3

HC

CH2OH

H2C

OOCH3

CH

CH2OH

HOHC

O

H2C

CH2OH

H2C

OH

H2C

CH2OH

CH

H3CO

R

OCH3

H3CO

O

O

OHHO

H3CO

H3CO

O

O

H3CO

OH

OH

OOH

HO O

HO

Lignin surrounds cellulose microfilbrils ,there by providing strength to the cell wall. Highly

heterogeneous material ,requires Oxygen for its degradation /modification .

•To understand the biodegradation of lignocellulose in soil

• To model the biodegradation of lignocellulose in soil

•To understand the biodegradation of lignocellulose in soil

• To model the biodegradation of lignocellulose in soil

Design the pretreatment system

Aim of the Project

Methodology

Scanning Electron Microscopy (SEM)

C2,C3,C5 of cellulose

C4 of amorphous and crystalline

cellulose

4 weeks 8 weeks

12 weeks16 weeks

Solid State NMR Analysis

Syringol

Guiacyl

Sinapyl,coniferyl

Batch samples for every four weeks

% C

once

ntr

atio

n o

f th

e to

tal

com

pou

nd

Pyrolysis-GC/MS Analysis

Thermogravitometric Analysis

temperature

0 5 10 15 200 250 300 350 400 450 500 550

Soil Sample S5

Soil sample S4,

After 20 weeks

After 16 weeks

After 12 weeks

After 8 weeks

After 4 weeks

Cellulose

Lignin

Hemicellulose

40

60

80

100

20

Weig

ht

perc

en

t (%

)

[S]+[X]+O2 + H2Osoil

pH

[p] +[s1] + co2 +[X]

Input = output +accumulation – generation

where in S = s1+ s2 + s3

.

X = x1 +x2 +x3 .

P = products ( glucose and other residual sugars ).S1 = modif ied lignin .

( s1 =cellulose , s2= hemicellulose, s3= lignin )

(Maximum microbial growth on the biomassrespectively )

General Equation for the Soil Degradation system

d(S1) / d(t) = -Vb1*S1*X1/(Ks1+S1)S1(0) = 0.71 # weight in gm/gm   #Cellulose Balance

d(S2) / d(t) = -Vb2*S2*X2/(Ks2+S2)S2(0) = 0.48 # weight in gm/gm   #Hemicellulose Balance

d(S3) / d(t) = -Vb3*S3*X3/(Ks3+S3)S3(0) = 0.28 # weight in gm/gm   #Lignin Balance

#Microbial Growth corresponding to Cellulosed(X1) / d(t) = μ1*X1 X1(0) = 0.1  #Microbial Growth corresponding to Hemicellulosed(X2) / d(t) = μ 2*X2

X2(0) = 0.1  #Microbial Growth corresponding to Lignind(X3) / d(t) = μ3*X3

X3(0) = 0.1  µ1=µmax1*S1/(Ks1+S1)-∆1 

µ2=µmax2*S2/(Ks2+S2)-∆2 µ3=µmax3*S3/(KS3+S3)-∆3

t(0) = 0t(f) = 3360 

Considering the values as follows ;µmax1=0.08µmax2=0.05μmax3=0.03 system.  ∆1=0.001∆2=0.001∆3=0.001

We derived an relation using polymath which defines the degradation pattern in the soil

Initial and final time periods of Incubation

Time (in hours )

Init

ial S

ubst

rate

co n

cent

r ati

on in

gm

/ gm

We derived an relation using polymath which defines the degradation pattern in the soil system.

Modeling

Application of the Model

The determination of the exact relation between the various factors with respect to the specific incubation period would be helpful in developing a model which would predict the specific ratio of cellulose, hemicellulose and lignin apart from other factors involved such as pH, temperature and other organic compounds.

Thus providing a suitable mechanism for the pretreatment technology !

Conclusion

Scientific Contribution:

Specific conditions which relates to the changes in the relative composition of cellulose,hemicellulose and lignin, Chemical changes in the lignin structure with respect to time as a result of which lignin modification in the soil takes place during the natural degradation process was determined

Implication: As the pathway of lignin degradation in soil is quite different this would provide us a scope for a novel method for lignin degradation process. Further work would involve understanding different factors which play an important role during the lignin modification and degradation .

I would like to thank

•Dr. Ann Kennedy USDA-ARS Soil Scientist/Adj. Prof. Crop and Soil Sciences,WSU.

•Dr. Greg Helms, NMR Center Director ,WSU.•Dr. Manuel Garcia-Perez. Assistant Professor / Scientist. Biological Systems Engineering ,WSU.•Dr. Bill , Assistant manager ,NMR Center,WSU.

And my Advisor …•Dr. Shulin Chen, Professor/Scientist. Department of Biological Systems Engineering,WSU .

My Team …

Thank you …

Any Questions ?