Transcript Investigation and modeling natural biodegradation system in soil

Investigation and modeling natural
biodegradation system in soil; application for
designing an efficient biological pretreatment
technology for Biofuel production.
Mythreyi Chandoor, Deepak Singh and Shulin Chen
Bioprocessing and Bioproduct Engineering Laboratory,
Department of Biological Systems Engineering
Washington State University .
Agenda
•Aim and importance of the project
• Background – Hypothesis of the project
• Experimental:
Microbiology
Chemical analysis of lignocellulose
degradation in soil
Structural analysis
• Modeling
Lignocellulose degradation in soil
Application
• Acknowledgements
Aim and importance of the
project
•Demand for an Alternate 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 ?
The greatest challenge lies in the deconstruction of
lignin part of the biomass to release sugars.
Need for novel pretreatment technology !!
Background
Natural biodegradation
system in soil
Cellulose
Hemicellulose
Microcosm
Lignin
Microcosm
Degraded into smaller
sub units. Amino
Chemically
modified
Other complex
compounds
Organic
Metal
Ions
acids
acids
Polyurinoids
Humus
Background
Lignocellulosic system in soil
Proteins
Delignification,
repolymerization
Humus
formation
in soil
Background
Possible lignin mechanism
in soil
Lignin
Microcosm
Chemically modified/partially degraded Lignin
Other
complex
compounds
Organic
acids
Amino
acids
Polyurinoids
Humus
Aim of the project
Background
• To
understand the biodegradation of
lignocellulose in soil
• To model the biodegradation of
lignocellulose in soil
Design the pretreatment system
Methodology
Experimental results
•SEM (Scanning Electron Microscopy)
• NMR(Solid State Nuclear Magnetic Resonance
Spectroscopy)
•1-D NMR (Nuclear Magnetic Resonance Spectroscopy )
• TG (Thermogravimetric Analysis )
• FTIR (Fourier Transform Infrared Spectroscopy)
• GC-MS (Gas Chromatography Mass Spectroscopy)
Scanning Electron Microscopy
(SEM)
Solid State NMR
Analysis
C2,C3,C5 of cellulose
Amorphous and crystalline compounds
attached to C4
C4 of
amorphous
cellulose
Aromatic carbons attached to
methoxy groups in syringol unit
4 weeks
8 weeks
12 weeks
16 weeks
Phenolmethoxyl of
coniferyl and
sinapyl moities
Solid State NMR
Analysis
•The amount of syringol and guaicol units of lignin
have increased after 16 weeks
•The Oxidation of syringyl and guaicyl units of
lignin will give rise to syringol and guaicol units.
Solid State NMR Analysis
Quantitatively , syringyl and guaicyl units have
decreased where as the syringol and guaicol amounts
have increased which shows that there is change in
the chemical nature of lignin structure
% Concentration
of the total compound
Py-GC/MS Analysis
10
9.5
9
8.5
8
7.5
lignin
7
sugars
6.5
6
5.5
5
4.5
4
3.5
3
0
1
2
3
4
Batch samples for every four weeks
5
Py-GC/MS Analysis
•The Change in the lignin polymer is observed after
the completion of 12 weeks.
•The increase in the lignin content is attributed to
the kind of subunits taken into consideration ;
Syringol ,guaicol , ethanone and others were
considered which are formed as a result of
oxidation or modification of lignin.
Py-GC/MS Analysis
Cellulose and Hemicellulose are proportionately
decreasing while the lignin concentration is stable
and increased after a period of 12 weeks
1H
NMR analysis
CONTROL
δ 3.81
Hα in β-structures
16 week SAMPLE
δ 3.81
1H
NMR analysis
•The signal at δ 3.81 ppm : methoxyl groups lower
in sample.Indicates the enzymatic modification of
the lignin molecules.
•Signals in δ 4.39 ppm: Hγ in β-O-4 structures and
β-5 structures and
•Signals in δ 5.49 ppm : Hα in β-5 structures
respectively.
1H
NMR analysis
•The low intensity of the protons in ß-O-4 units with
biodegradation confirms the ß-O-4 linkage degradation
during the biological degradation process.
•δ 6.93 ppm, δ 7.41 ppm, δ 7.53 ppm corresponding to
aromatic protons (certain vinyl protons), aromatic protons
in benzaldehyde units and vinyl protons on the carbon
atoms adjacent to aromatic rings in cinnamaldehyde units
and aromatic protons in benzaldehyde units respectively
were in low intensity in the 16 week samples.
TG Analysis
After 20 weeks
After 16 weeks
After 12 weeks
After 8 weeks
After 4 weeks
Soil Sample S5
Soil sample S4,
0
5
10
15
200
Lignin
Sugars
250
300
350
40
45
50
55
min
Modeling
Modeling
C02 Balance equation :
dm CO2 /dt = (dmCO2bio/dt- mCO2 dvexhaust /dt )/v
mCO2 = Mass of CO2 in soil
dm CO2bio = evolution of CO2 during Bioreaction
V= free space in the soil
dvexhaust /dt = flow of exhaust air
t = time
dmCO2bio/dt = negligible ;
The change in the flow of the exhaust air is also negligible
dmCO2/dt = Negligible
Therefore not being considered .
Modeling
d(S1) / d(t) = -Vb1*S1*X1/(Ks1+S1) #Cellulose Balance
S1(0) = 0.71 # weight in gm/gm
d(S2) / d(t) = -Vb2*S2*X2/(Ks2+S2) #Hemicellulose Balance
S2(0) = 0.48 #
d(S3) / d(t) = -Vb3*S3*X3/(Ks3+S3) #Lignin Balance
S3(0) = 0.28 #
Modeling
µ=µmax1*S1/(Ks1+S1)-∆1
t(0) = 0
t(f) = 3360
µ2=µmax2*S2/(Ks2+S2)- ∆ 2
µ3=µmax3*S3/(KS3+S3)- ∆ 3
Considering the values as follows ;
µmax1=0.08
µmax2=0.05
μmax3=0.03
∆ 1=0.001
∆ 2=0.001
∆ 3=0.001
We derived an relation using polymath which defines the degradation
pattern in the soil system.
Modeling
Time (in hours )
Application of the model
•The model developed is a relation drawn
between the total initial concentrations of the
cellulose, hemicellulose and lignin , defined in
a specific proportion at any point of time .
•Further ,the model would correlate the
various factors involved parallel to the
degradation rates of each component
respectively.
Conclusion
Based on the different experiments
conducted on the samples which were
incubated for 4,8,12,16 and 20 weeks it has
been observed that :
•The optimized conditions for lignin modification is obtained
after a period of 16 weeks .
•These optimized conditions are in relation to various
factors present in the soil system, with respect to the relative
proportion of each component .
Conclusion
The determination of the exact relation
between these factors 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 !!
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 …
Acknowledgements
And
Any Questions ?