Birgitte K. Ahring,

Diwarkar Rana, Vandana Rana, Philip Teller

Bioproducts, Sciences & Engineering Laboratory

Pretreatment of lignocellulosic materials using wet explosion

Lignin

Hemicellulose

Cellulose

53-73 psi

175-195 C

O2

O2

O2

O2

C5 – C6 Sugars

O2

O2

O2

O2

O2

O2

O2

O2

O2

O2

O2

O2

Glucose Oligomeric

and Polymeric

Chains

Lignin Products

Xylooligosaccharides

Oxygen under

pressure cleaves with

substitution positions

in lignin chains

The lignin and

hemicellulose chains

disintegrates within

seconds of flashing

the WetOx reactor

Lignocellulosic

biomass can consist of

three main

components

Wet Oxidation

Woody

Biomass

Wet OxidationBiomass

Process Parameters

Temp: 170 – 185 deg C

Time: 20-30 min

Oxygen < 10 bar

Pretreated Biomass

Flash

valve

Flash Tank

Oxygen

WET EXPLOSION PRETREATMENT

3

Wet oxidation pretreatment

Wet oxidation conditions:

@ 180ºC, 15 bar, addition of O2

Increasing the bioavailability + convertibility

to

Breaking the

lignocellulosic

structure of straw,

manure fibers etc.

MaxiFuels biorefinery concept

MaxiFuels = Biorefinery for bioethanol production

from lignocellulosic biomass with conversion of

residuals into biogas, hydrogen, and solid lignin

Xylose

Fermentation

LIGNIN

BY-PRODUCTS

Xylose

Fermentation

LIGNIN

BY-PRODUCTS

MAXIFuels pilot plant – started September 2006

Pretreatment

Enzymatic hydrolysis

+ C6 fermentation

C5 fermentationDistillation

Anaerobic

digestion

MaxiFuels biorefinery concept

Optimized use of the biomass

Oxidized in the pre-

treatment

Ethanol from glucose

Ethanol from xylose

Lignin for combustion

Biogas

Organic material in

the process water

Mass balance based on COD

3% 4%

19%

20%19% 35%

1

2

3

Pretreated

slurry

WEx

PretreatmentEnzymatic

Hydrolysis

Milled corn

stover

HPLC: Free sugars

in liquid fraction

Selection of WEx conditions

4

WEx at platform

conditions

5

Enzymatic

Hydrolysis

Optimization

Selection of EH

conditions

Hydrolyzate

7

6

HPLC: Free sugars

in liquid fraction

EH at optimum conditions

8

9

Scale Up

SEM: Changes in

ultrastructure

10

Process Economics

study

Hydrolyzate

Schematic of the study

CS-8 WEx sample hydrolyzed @ 15 and 40 mg/g glucan

0

20

40

60

80

100

PT 24 48 72

Su

ga

r co

nce

ntr

ati

on

, g

/L

Time, hours

Glucose-40 mg

Glucose-15 mg

Xylose-40 mg

Xylose-15 mg

Wet oxidation process – pilot-scale

Wet oxidation

reactor

Flash tank

Batch experiments – wet oxidation

Wet oxidation of whole manure Wet oxidation of manure fibers

0

50

100

150

200

0 10 20 30 40 50

Time (days)

Me

tha

ne

yie

ld (

L/k

g-V

S)

Wet ox fibers

Untreated fibers

0

100

200

300

400

0 10 20 30 40 50 60

Time (days)

Meth

an

e y

ield

(L

/kg

-VS

)

wetoxidized cattle manure

raw cattle manure

Reactor experiment – wet oxidized manure

0

100

200

300

400

500

600

700

0 10 20 30 40 50 60 70

Time (days)

Bio

gas

yie

ld (

L/k

g-V

S)

R1 biogas yield R1 biogas yield avg

R2 biogas yield R2 biogas yield avg

Wet oxidized manure feed to R1

Wet oxidation of manure fibers

0

20

40

60

80

100

120

140

160

180

20% 30% 40% 50% 60% 100%

% Fiber- VS of total VS in mixture with manure

Bio

ga

s y

ield

of

fib

ers

(m

3/t

-fib

ers

)

Wox fibers Raw fibers

Biogas yield from manure

66 kgTS/tDry matter

Water

>90%

< 25 m3biogas/t

Solid phase:

15 m3

biogas/t

Liquid phase:

10 m3

biogas/t

Increase of biogas yield per ton manure

Wet oxidation of fibers:

66 kgTS/tDry matter

Water

>90%

40 m3biogas/t Solid phase:

30 m3

biogas/t

Liquid phase:

10 m3

biogas/t

BIOGAS

PLANT

Biogas

Separation

Electricity

Heat

Fibers

Manure CHP

Electricity

to grid

District

HeatingGas

motor

Fibers

P-Fertilizer

Liquid

N-Fertilizer

FARM

Fibers

FARM

FIELD

Liquid

N-FertilizerO2

Wet

oxidation

Wetox Fibers

Separation of fibers + wet oxidation of recycled fibers

ManureFARM

Heat

BIOGAS

PLANT

Biogas

Electricity

Heat

CHP

Electricity

to grid

District

HeatingGas

motor

Fibers

FARM

FIELD

Liquid

N-Fertilizer

O2

Wet

oxidation

P-Fertilizer

Separation + wet oxidation of fibers

FibersFARM

FARM

Heat

18

RAW COMPOSITION

44.68%

2.49%2%2.09%

11.82%

29.58%

Douglas Fir

Glucan Xylan Galactan

Arabinan Mannan Lignin

Pretreatment ReactorFlash Tank

Washington State University – Pretreatment Pilot Plant

PILOT PLANT

20

Softwood to hydrolysate and sugars

Raw Softwood

Milling

Pretreatment

Enzymatic

Hydrolysis

Sugars Yields from Softwood

Type of BiomassType of

Pretreatment

Pretreatment

Temperature (0C)-Time (min)

Enzymatic

Hydrolysis

Theoretical

Yield

(Total Sugars)

Reference

SoftwoodTwo- step Steam

Pretreatment

Stage 1: 190-2, 3% SO2

Stage 2: 220-5, 3% SO22% DM 80%

Söderström J. et al.

(2002)

Pinus rigida Organosolv 210-10, 1% MgCl2 1% DM 75.88% Park N. et al. (2010)

Bettle Killed LodgepoleOne step Steam

Pretreatment200-5, 4% SO2 2% DM 75% Ewanick S. et al. (2007)

Loblolly pine Wet Explosion180-20, 6 bar O2

25% DM 96.00% Rana D. et al. (2012)

Conclusion

• Wet explosion was found to be well suited as a pretreatment method for production of ethanol and biogas from agricultural residues

• Wet explosion was further found to produce high sugar yields (both C6 and C5) from softwood

• Enzyme cost demands that hydrolysis of pretreated materials has to be optimized

• Economics might be more favorable for non-maximum sugar production from biomass materials

• Pretreatment of forest slash needs upfront processing before pretreatment

Thank you and Questions

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Washington State University

Center for Bioproducts and Bioenergy

Phone: 509.372.7683

Email: cbb@tricity.wsu.edu

Web: www.tricity.wsu.edu/bsel