irene bohn

17
Anaerobic digestion of crop residues at low temperatures Irene Bohn Irene Bohn LUND UNIVERSITY Department of Biotechnology

Upload: sabina

Post on 22-Jan-2016

69 views

Category:

Documents


0 download

DESCRIPTION

Irene Bohn. LUND UNIVERSITY. Anaerobic digestion of crop residues at low temperatures. Department of Biotechnology. Digestion of manure on the farm Degradation of low strength wastewaters + high strength wastewaters Post digestion or storage. Background. Low temperature digestion:. - PowerPoint PPT Presentation

TRANSCRIPT

Page 1: Irene Bohn

Anaerobic digestion of crop residues at low temperatures

Irene BohnIrene Bohn

LUND UNIVERSITY

Department of Biotechnology

Page 2: Irene Bohn

Lund University, Department of Biotechnology

Background

Digestion of manure on the farmDegradation of low strength wastewaters + high strength wastewatersPost digestion or storage

Low temperature digestion:

Is low-temperature digestion of crop residues feasible?

Page 3: Irene Bohn

Lund University, Department of Biotechnology

Motivation

0

4

8

12

16

20

Slu

dg

efr

om

wa

ste

wa

ter

tre

atm

en

t

Mu

nic

ipa

lso

lid w

ast

e

Ind

ust

rial

wa

ste

s

Ma

nu

re

Cro

pre

sid

ue

s

Tota

l

TW

h p

er

yea

r Digested

Available

?

Nordberg et al. 1998. Biogaspotential och framtida anläggningar i Sverige. Kretslopp och avfall No 17, JTI, VBB Viak, Uppsala.

The Swedish Biogas Association, 2001. Swedish Biogas production 2001.

Page 4: Irene Bohn

Lund University, Department of Biotechnology

Reactor types

Commercially available reactor

High

High

Low

Modified manure tank

Low

Low

High

Cost

Capacity vs. volume

Heat loss

Page 5: Irene Bohn

Lund University, Department of Biotechnology

Inoculum: Digested cow manure from unheated anaerobic digestion tank

Total volume:2.2 m3 Active volume: 1.8m3

Digester set-up

Kg

Substrate: Ensiled sugar beet tops and straw

4.5 % volatile solids in ready substrate

Page 6: Irene Bohn

Lund University, Department of Biotechnology

Effect of temperature on yield

0.00

0.10

0.20

0.30

0.40

0.50

10 15 20 25 30 35 40

Temperature (°C)

Me

tha

ne

yie

ld (

m 3 C

H4

kg V

S-1

)

Loading rate: 0.5 kg VS m-3 d-1 and hydraulic retention time: 90 days

Methane yield decreased with decreasing temperature but no VFAs accumulated at the high hydraulic retention

time

Hydrolysis was limiting the methane yield

Page 7: Irene Bohn

Lund University, Department of Biotechnology

0.00

0.05

0.10

0.15

0.20

0.25

0.30

0.35

0.40

0.45

0.5 1.0 1.6 2.0 3.3 4.1

OLR (kg VS/m3,day)

m3 C

H4/k

g V

S

15°C

30°C

Yield and rate

0.00

0.20

0.40

0.60

0.80

1.00

1.20

0.5 1.0 1.6 2.0 3.3 4.1

OLR (kg VS/m3,day)

m3 C

H4/m

3,d

ay

15°C

30°CMethane production

rate

Methane yield

Page 8: Irene Bohn

Lund University, Department of Biotechnology

Stirrer

Heating-substrate

Heating-reactor

Substrate

Gas

0

500

1000

1500

2000

2500

3000

3500

4000

Ou

tpu

t

Inp

ut

Ou

tpu

t

Inp

ut

Ou

tpu

t

Inp

ut

0.5 1 1.6

OLR (kgVS/m3,day)

kW

h/tV

S

0

500

1000

1500

2000

2500

3000

3500

4000

Ou

tpu

t

Inp

ut

Ou

tpu

t

Inp

ut

Ou

tpu

t

Inp

ut

0.5 1 3.1

OLR (kgVS/m3,day)

kW

h/tV

S

Energy-balance

15C 30C

Page 9: Irene Bohn

Lund University, Department of Biotechnology

Stirrer

Heating-substrate

Heating-reactor

Substrate

Gas

Energy-balance

0

500

1000

1500

2000

2500

3000

3500

4000O

utp

ut

Inp

ut

Ou

tpu

t

Inp

ut

Ou

tpu

t

Inp

ut

0.5 1 1.6

OLR (kgVS/m3,day)

kWh

/tVS

0

500

1000

1500

2000

2500

3000

3500

4000

Ou

tpu

t

Inp

ut

Ou

tpu

t

Inp

ut

Ou

tpu

t

Inp

ut

0.5 1 3.1

OLR (kgVS/m3,day)

kWh

/tVS

15C 30C

Page 10: Irene Bohn

Lund University, Department of Biotechnology

0.00

0.10

0.20

0.30

0.40

0.50

15 22 30 37

Temperature (°C)

m3 C

H4/

kg

VS

15°C

30°C

Yield obtained in batch-experiments

•The effect of temperature on yield was lower for the sludge adapted to 15C

2821 23 23

•The yield in the batch-experiment was higher than in the reactor

Page 11: Irene Bohn

Lund University, Department of Biotechnology

Accumulation of acetate and propionate

Acetic acid

Propionic acid

Butyric acid

Valeric acid

OLR in

kg VS m-3 day-1

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

20-Mar 9-May 28-Jun 17-Aug 6-Oct 25-Nov

Co

nce

ntr

atio

n o

f vo

latil

e fa

tty a

cid

s

(g l-1

)

OLR = 1 OLR = 2 OLR = 1.5

OLR = 0

0

0.5

1

1.5

2

2.5

3

3.5

20-Mar 9-May 28-Jun 17-Aug 6-Oct 25-Nov 14-Jan

Co

nce

ntr

atio

n o

f vo

latil

e fa

tty a

cid

s

(g l-1

)

OLR = 1 OLR = 2 OLR = 3

OLR = 4

OLR = 0.5

Results from continuously stirred pilot scale reactors fed with beet top slurry

30 C15 C

Page 12: Irene Bohn

Lund University, Department of Biotechnology

Packed-bed methane-filters

Inoculum: Sludge from pilot-scale reactors or lake sediment

Substrate: Leachate from ley-crop silage

Page 13: Irene Bohn

Lund University, Department of Biotechnology

0.0

0.2

0.4

0.6

0.8

1.0

25 50 75 100Time (days)

Co

nce

ntr

atio

n (

g l-1

) 0.57±0.13 0.39±0.08

0.0

0.2

0.4

0.6

0.8

1.0

25 50 75 100Time (days)

Co

nce

ntr

atio

n (

g l -1

) 0.52±0.09 0.43±0.05

Results from methane-filtersAcetic acid

Propionic acid

OLR in

kgCOD m -3 day-1

10 C15 C

During start-up:

0.0

0.2

0.4

0.6

0.8

1.0

16-Aug 15-Sep 15-Oct 14-Nov 14-Dec

Co

nce

ntr

atio

n (

g l -1

)

0.50±0.08

0.81±0.08

1.03±0.08

After1 year:

0.0

0.2

0.4

0.6

0.8

1.0

16-Aug 15-Sep 15-Oct 14-Nov 14-Dec

Co

nce

ntr

atio

n (

g l -1

)

0.49±0.06

0.80±0.08

1.00±0.08

Page 14: Irene Bohn

Lund University, Department of Biotechnology

Acetate

Propionate

other VFAsUnidentified

CH4 produced

0

3

6

9

12

15

0 1 2 3 4 5

OLR (gCOD l-1 d-1)

Un

de

gra

de

d V

FA

(%

of i

nle

t CO

D)

0

20

40

60

80

100

CH

4 -C

OD

pro

du

ced

(% o

f in

let C

OD

)

0

3

6

9

12

15

0 1 2 3 4

OLR (gCOD l-1 d-1)

Un

de

gra

de

d V

FA

(%

of i

nle

t CO

D)

0

20

40

60

80

100C

H4 -

CO

D p

rod

uce

d

(% o

f in

let C

OD

)

0

3

6

9

12

15

0 1 2 3 4

OLR (gCOD l-1 d-1)

Und

egra

ded

VF

A

(% o

f inl

et C

OD

)

0

20

40

60

80

100

CH

4 -C

OD

pro

duce

d

(% o

f inl

et C

OD

)

0

3

6

9

12

15

0 1 2 3 4 5

OLR (gCOD l-1 d-1)

Un

de

gra

de

d V

FA

(%

of i

nle

t CO

D)

0

20

40

60

80

100

120

CH

4 -C

OD

pro

du

ced

(% o

f in

let C

OD

)

Lake sediment

Reactor sludge

15 C 10 C

Results from methane-filters

Page 15: Irene Bohn

Lund University, Department of Biotechnology

Results from methane-filters

0

20

40

60

80

100

120

140

15

°C-R

15

°C-L

10

°C-R

10

°C-L

15

°C-R

15

°C-L

10

°C-R

10

°C-L

15

°C-R

15

°C-L

10

°C-R

10

°C-L

15

°C-R

15

°C-L

10

°C-R

10

°C-L

15

°C-R

15

°C-L

10

°C-R

10

°C-L

15

°C-R

15

°C-L

10

°C-R

10

°C-L

15

°C-R

15

°C-L

10

°C-R

10

°C-L

0.5 0.8 1.0 1.5 2.0 3.0 4.5

OLR (kg COD/m3,day)

CO

D a

s %

of

inle

t

Unidentified

Other VFAs

Propionate

Acetate

Methane

Page 16: Irene Bohn

Lund University, Department of Biotechnology

Yield from solid substrate decreases with temperatureFeasibility of low temperature digestion depends on

insulation of the reactorutilization of the capacity

High yield is obtained for soluble substrate at 10°C

Conclusions

Page 17: Irene Bohn

Lund University, Department of Biotechnology

Acknowledgements

Financiation:

The Energy Supply Comittee of Southern Sweden (DESS)The Swedish Research Council (VR)The Swedish Energy Agency (STEM)

Co-authors:

Bo MattiassonLovisa BjörnssonAndreas BengtssonMelvice Bessem Ayuk