irene bohn
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 PresentationTRANSCRIPT
Anaerobic digestion of crop residues at low temperatures
Irene BohnIrene Bohn
LUND UNIVERSITY
Department of Biotechnology
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?
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.
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
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
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
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
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
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
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
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
Lund University, Department of Biotechnology
Packed-bed methane-filters
Inoculum: Sludge from pilot-scale reactors or lake sediment
Substrate: Leachate from ley-crop silage
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
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
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
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
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