department of food and nutritional sciencesuest.ntua.gr/athens2017/proceedings/presentations/... ·...

LIMITLESS POTENTIAL | LIMITLESS OPPORTUNITIES | LIMITLESS IMPACTLIMITLESS POTENTIAL | LIMITLESS OPPORTUNITIES | LIMITLESS IMPACTLIMITLESS POTENTIAL | LIMITLESS OPPORTUNITIES | LIMITLESS IMPACTCopyright University of Reading

THERMAL PRE-TREATMENT OF LIGNOCELLULOSIC BIOMASS AS A SUBSTRATE FOR ANAEROBIC DIGESTION

F. Kaldis, D. Cysneiros, A. Chatzifragkou, K.A. Karatzas

1

Department of Food and

Nutritional Sciences

LIMITLESS POTENTIAL | LIMITLESS OPPORTUNITIES | LIMITLESS IMPACT

ANAEROBIC DIGESTION

2

Renewable fuels

(Digestate)

Anaerobic bacteria (inoculum)

Intricate structure

Lignin content


PRETREATMENT CHOICE

1. Physical (maceration of the substrate)

2. Chemical (alkali or acid pretreatment)

3. Biological (the use of fungi)

4. Hydrothermal (steam explosion)

• Biomass structure opens up due to thermal expansion, (reduction of the particle size and an increase in the pore volume)

• The polysaccharides are hydrolysed to simpler sugars

• Higher degradation rates from the microorganisms of AD

3


AIMS

• Effect of different retention times in a thermal pre-treatment and the correlation between this and the organic load rate of mesophilic anaerobic bioreactors

• Introducing the liquid part of the thermal pretreatment in AD systems and assessing its effects

• Modeling the biomethane production data of the experiment using an one phase exponential model

4


MATERIALS AND METHODS

• Batch mode (mesophilic conditions)

• Inoculum :The effluent of a full scale biogas plant (digesting crops )

• Substrate: Wheat straw (WS)

• Pretreatment: high temperature (140 °C) and pressure (2.75 bars))

• Retention times (0, 30, 60 and 90 minutes)

• OLR (2, 4, 8 and 12 Kg VS/m3 )

5


EFFECT OF THE PRE-TREATMENT ON THE WS

6

0,00

20,00

40,00

60,00

80,00

100,00

Co

nce

ntr

ati

on

(g

/10

0g

)

Total solids

untreated

30 min

60 min

90 min

0

20

40

60

80

100

Glucose Xylose Arabinose

Co

nce

ntr

ati

on

(g

/10

0g

)

Sugars

untreated

30 min

60 min

90 min

• The pores of the substrate were opened and the water absorption from the WS increased

• Part of the sugars were released from the lignocellulosic structure and passed into the liquid phase (no washing step was carried out)

• The increase trend in lignin concentration can be attributed to the formation of cross-linked aromatic compounds due to the pre-treatment

0,00

10,00

20,00

30,00

40,00

Co

nce

ntr

ati

on

(g

/10

0g

)

Lignin

untreated

30 min

60 min

90 min


CH4 PRODUCTION (L/KG VS)

7

0,00

0,05

0,10

0,15

0,20

0,25

0,30

0,35

0,40

0,45

0,50

untr

eate

d

30

min

60 m

in

90 m

in

untr

eate

d

30

min

60 m

in

90

min

untr

eate

d

30

min

60 m

in

90

min

untr

eate

d

30

min

60 m

in

90

min

Ym

ax

(m3

/kg

VS

)

OLR 2 OLR 12OLR 8OLR 4

• 𝑌 = 𝑌𝑚𝑎𝑥 (1 − 𝑒−𝑘 𝑡−𝑡𝑙𝑎𝑔 )• OLR of 2 kg/ m3, a retention time of 60 min was more efficient• OLR of 12 kg/ m3, a pre-treatment of 60 or 90 min led to increased

biomethane production


EFFECT OF THE LIQUID ADDITION

0

100

200

300

CH

4p

rod

uct

ion

(L

/Kg

VS

)OLR2

untreated solids

treated solids

whole slurry

8

0

100

200

300

CH

4p

rod

uct

ion

(L

/Kg

VS

)

OLR4

untreated solids

treated solids

whole slurry

0

100

200

300

CH

4p

rod

uct

ion

(L

/Kg

VS

)

OLR8

untreated solids

treated solids

whole slurry

0

100

200

300

CH

4p

rod

uct

ion

(L

/Kg

VS

)

OLR12

untreated solids

treated solids

whole sulrry

• AD systems with lower organic loads seemed to be more affected by the addition of the liquid fraction of the pre-treatment

• It is believed that the amount of active microorganisms is playing vital role for the digestion of the thermal treated samples


CONCLUSIONS

• Thermal pre-treatment was successfully applied on WS prior to anaerobic digestion.

• This specific pre-treatment seems to have different effect on the process under different OLR.

1. OLR of 2 kg/ m3 favoured 60 min treatment

2. OLR of 12 kg/ m3 favoured 60 or 90 min treatment

• Anaerobic bioreactors are more likely to handle higher OLR when fed with thermally pre-treated lignocellulosic biomass. In that way, higher volumetric methane yields can be achieved, maintaining the biogas output of existing Plants.

9


GREAT THANKS

10

Supervisors team: Dr. Kimon-Andreas Karatzas*, Dr. Aphrodite Chatzifragkou, Dr. Denise CysneirosDr. Karatzas group:Marcia, Carolina, Ruth, Oluwabunmi and Ranju

Contact: [email protected]@pgr.reading.ac.uk

department of food and nutritional sciencesuest.ntua.gr/athens2017/proceedings/presentations/... ·...

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