experiences with mechanical pre- treatment of horse-dung ......mechanical thermic. hans oechsner and...
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Der Landwirt als Energiewirt -
Biogaserzeugung in der
LandwirtschaftDr. Hans Oechsner; Dr. Matthias Mönch-TegederState Institute of Agricultural Engineering and Bioenergy,
University of Hohenheim
Experiences with mechanical pre-
treatment of horse-dung on a biogas plant
(190 kW)
Malmö, 10. September 2015
Hans Oechsner and Matthias Mönch-Tegeder
Experinces with mechanical pre-treatment of horse-dung on a biogas plant
3rd IBBA workshop, in Malmö, Sweden, September 10th 2015
2
Biological energy conversion efficiency
of different substratesE
nerg
y c
on
vers
ion
rate
(%
)
80%75%
68%
45%40%
15%
0%
10%
20%
30%
40%
50%
60%
70%
80%
90%
Umsetzrate GE zu Biogasenergie
Sugar
beet
Maize
silage
4-cut-
grassland,
intensive
2-cut-
grassland,
extensive
Wheat
straw
Silage of nature
protection area
Around 8000 Full scale biogas plants in Germany
Substrate use about 115 Mio. t FM per year, >50 % energy crops, costs
Alternative substrates?
Hans Oechsner and Matthias Mönch-Tegeder
Experinces with mechanical pre-treatment of horse-dung on a biogas plant
3rd IBBA workshop, in Malmö, Sweden, September 10th 2015
3
Research project with horse manure,
funded by the Federal Ministry of Environment
Aims of the project:
To determine of digestibility of
this fibrous substrate
To increase the degradability and
efficiency
To optimize the managability in
the digester
To increase the methane yield
To use the horse manure as
energy source
Hans Oechsner and Matthias Mönch-Tegeder
Experinces with mechanical pre-treatment of horse-dung on a biogas plant
3rd IBBA workshop, in Malmö, Sweden, September 10th 2015
4
Horse manure as feed stuff for biogas plants?
More than 1 Million horses in Germany
Manure production: 17 - 20 t per horse and year
50 – 70 % straw fraction (fluctuating)
Lack of space at the farms for storage and
disposal problems
Problems in the surroundig of towns
High costs of disposal
→ Energetic use in biogas plants
will be a chance
Häußermann et al., 2002; Beck, 2005; Winter, 2014
Hans Oechsner and Matthias Mönch-Tegeder
Experinces with mechanical pre-treatment of horse-dung on a biogas plant
3rd IBBA workshop, in Malmö, Sweden, September 10th 2015
6
High fiber content causes
process engineering problems
Floating layer
Blockage of
leakage
possible
Increasing
viscosity –
energy
consumptionSlow conversion
Hans Oechsner and Matthias Mönch-Tegeder
Experinces with mechanical pre-treatment of horse-dung on a biogas plant
3rd IBBA workshop, in Malmö, Sweden, September 10th 2015
7
Digestibility of horse manure
Material and methods
Substrate from 10 farms:
Used litter (straw, straw pellets, flax straw, wood shavings and
wood pellets)
Horse dung
Horse dung mixed with different litter materials
Fresh and stored manure
Analysis of composition
Weender and van Soest analysis
Concentration of trace elements
Analysis of biogas- and methane yields
Hohenheim Biogas Yield Test (HBT)
VDI-regulars 4630 (35 days)
Hans Oechsner and Matthias Mönch-Tegeder
Experinces with mechanical pre-treatment of horse-dung on a biogas plant
3rd IBBA workshop, in Malmö, Sweden, September 10th 2015
8
Digestibility of horse manure
Specific methane yield of different litter materials
0,205
0,247
0,067
0,021 0,017
0,000
0,050
0,100
0,150
0,200
0,250
0,300
Stroh Strohpellets Flachsstroh Holzpellets Sägespäne
Cu
mu
lati
ve
meth
an
eyie
ld[m
³ /
kg
VS
]
standardized: 1013 hPa, 273,15 K
Horse dung with straw straw pellets flax straw wood pellets w. shavings
Hans Oechsner and Matthias Mönch-Tegeder
Experinces with mechanical pre-treatment of horse-dung on a biogas plant
3rd IBBA workshop, in Malmö, Sweden, September 10th 2015
9
Digestibility of horse manure
Specific methane yield - age of manure
0,205
0,176
0,198
0,150
0,000
0,050
0,100
0,150
0,200
0,250
Einstreu Pferdekot Pferdemist "frisch" Pferdemist "gelagert"
Cu
mu
lati
ve
meth
an
ep
rod
ucti
on
[m³
/ kg
VS
]
Straw litter horse dung horse manure horse manure
fresh storedstandardized: 1013 hPa, 273,15 K
- 24 %
Hans Oechsner and Matthias Mönch-Tegeder
Experinces with mechanical pre-treatment of horse-dung on a biogas plant
3rd IBBA workshop, in Malmö, Sweden, September 10th 2015
10
Digestibility of horse manure
Results
Good digestibility of horse manure with straw
as litter
VS: Horse manure 198 m³ CH4 / t
- (Maize 330 – 350 m³ CH4 / t )
FM: Horse manure 80 m³ CH4 / t
- (Maize 100 – 120 m³ CH4 / t)
Insufficient decomposition with alternative
litter materials
Storage causes a considerable loss of
organic components and loss of methane
yield (24 % less)
Content of trace elements comparable with
grass silage
Hans Oechsner and Matthias Mönch-Tegeder
Experinces with mechanical pre-treatment of horse-dung on a biogas plant
3rd IBBA workshop, in Malmö, Sweden, September 10th 2015
11
Conditioning of substrate
Plants or parts of plants with high fiber
fraction
Lignocellulose – hindering for digestion
Will it be possible, to enhance
anaerobic digestion by conditioning ?
Schwarz et al., 2009
Micro fibre structure
physical
chemical biological
- hot water
- steam
- thermo-
pressure-
hydrolysis
- acid
- base
- oxidant
- enzymes- shearing strain
- pressure
thermicmechanical
Hans Oechsner and Matthias Mönch-Tegeder
Experinces with mechanical pre-treatment of horse-dung on a biogas plant
3rd IBBA workshop, in Malmö, Sweden, September 10th 2015
12
0,00
0,05
0,10
0,15
0,20
0,25
0,30
0,35
0,40
0 5 10 15 20 25 30 35 40
sp
ec
ific
me
tha
ne
yie
ld[m
3/k
g o
DM
]
Retention time [d]
Weizenstroh 1 mm
Weizenstroh 5 mm
Weizenstroh 10 mm
Wheat straw 1 mm
Wheat straw 5 mm
Wheat straw 10 mm
Wheat straw – different particle size
Effect of grinding
+ 30 %
Slotjuk, 2011standardized: 1013 hPa, 273,15 K
Hans Oechsner and Matthias Mönch-Tegeder
Experinces with mechanical pre-treatment of horse-dung on a biogas plant
3rd IBBA workshop, in Malmö, Sweden, September 10th 2015
13
Mechanical pretreatment
Requirements
Text
Increasing of
particle surface
and
force up of
conversion rate
Optimizing of
viscosity
Reducing the loss
of organic
components
Prevention of
inhibiting effects
Low investment
costs and
low operating
costs
Avoiding process
engineering
problems
Taherzadeh und Karimi, 2008; Agbor et al., 2011
Hans Oechsner and Matthias Mönch-Tegeder
Experinces with mechanical pre-treatment of horse-dung on a biogas plant
3rd IBBA workshop, in Malmö, Sweden, September 10th 2015
14
Systems used in full scale biogas plants
for mechanical treatment of substrate
Rotacut Ball Mill Cross Flow Grinder
Shredder Extruder Impact Reactor
FREY, 2014 FREY, 2014
JENZ GMBH, 2014 BTS BIOGAS GMBH, 2014 BTS BIOGAS GMBH, 2014
MÖNCH-TEGEDER, 2014
Hans Oechsner and Matthias Mönch-Tegeder
Experinces with mechanical pre-treatment of horse-dung on a biogas plant
3rd IBBA workshop, in Malmö, Sweden, September 10th 2015
15
Mechanical pretreatment as possible solution –
cross flow grinder
• primarily recycling industrie
• working chamber diameter: 0.9 to 2.5 m
• connection power 55 to 315 kW
• number of rotation: 1200 /min
• working in batch or continuously
rotating chains
Hans Oechsner and Matthias Mönch-Tegeder
Experinces with mechanical pre-treatment of horse-dung on a biogas plant
3rd IBBA workshop, in Malmö, Sweden, September 10th 2015
16
Mechanical desintegrated substrate
Maize silage 15 sec 30 sec
Horse manure 15 sec 30 sec
Hans Oechsner and Matthias Mönch-Tegeder
Experinces with mechanical pre-treatment of horse-dung on a biogas plant
3rd IBBA workshop, in Malmö, Sweden, September 10th 2015
17
Wet sieving of the pretreated horse manure
- Variation of treatment time
0,0
10,0
20,0
30,0
40,0
50,0
60,0
70,0
80,0
90,0
<1,0 1,0≤ bis <2,0 2,0≤ bis <10,0 10≤
Shar
e o
f m
ass
fra
ctio
n
[%]
Size range [mm]
Horse manure control
Horse manure 15 sec.
Horse manure 30 sec.
> 10
Hans Oechsner and Matthias Mönch-Tegeder
Experinces with mechanical pre-treatment of horse-dung on a biogas plant
3rd IBBA workshop, in Malmö, Sweden, September 10th 2015
18
0,00
0,05
0,10
0,15
0,20
0,25
0,30
0,35
0,40
0,45
0 5 10 15 20 25 30 35 40
Sp
ezif
isc
he
r M
eth
an
ert
rag
(N
m3
/ k
g o
TS
)
Verweilzeit (Tage)
Maissilage QZ 30 sec
Maissilage QZ 15 sec
Maissilage Kontrolle
Pferdemist QZ 30 sec.
Pferdemist QZ 15 sec.
Pferdemist Kontrolle
Maize silage 30 sec
Maize silage 15 sec
Maize silage control
Horse manure 30 sec
Horse manure 15 sec
Horse manure control
Mechanical disintegration –
different substrates
+ 16
bis
+24 %
0 bis
+ 6 %
Digestion time [days]
Specific
meth
ane
yie
ld[m
³/kg V
S]
standardized: 1013 hPa, 273,15 K
Hans Oechsner and Matthias Mönch-Tegeder
Experinces with mechanical pre-treatment of horse-dung on a biogas plant
3rd IBBA workshop, in Malmö, Sweden, September 10th 2015
19
Mechanical pretreatment
Optic effectContinuously 10 cm gap
5 s
10 s 15 s
Untreated control
30 s
Hans Oechsner and Matthias Mönch-Tegeder
Experinces with mechanical pre-treatment of horse-dung on a biogas plant
3rd IBBA workshop, in Malmö, Sweden, September 10th 2015
20
Mechanical pretreatment
Specific methane yield – horse manure
Variation of treatment intensity
0,236
0,241
0,2470,249
0,257
0,249
0,200
0,210
0,220
0,230
0,240
0,250
0,260
0,270
0 10 cm 5 s 10 s 15 s 30 s
sp
ezif
icm
eth
an
eyie
ld[N
m³/
kg
VS
]
Hans Oechsner and Matthias Mönch-Tegeder
Experinces with mechanical pre-treatment of horse-dung on a biogas plant
3rd IBBA workshop, in Malmö, Sweden, September 10th 2015
23
Mechanical pretreatment
Energy consumption of cross flow grinder
11.6 11.3 11.813.8
10.7
14.8 14.0
16.3
20.5
15.2
0,0
5,0
10,0
15,0
20,0
25,0
En
erg
yco
nsu
mp
tio
n[k
Wh
/t F
M]
15
s
30
s
15
s
30
s
15
s
30
s
15
s
30
s
15
s
30
s
Maize Grass Total plant Horse Substratesilage silage silage manure mix
DM-content has an influence on energy consumption
Hans Oechsner and Matthias Mönch-Tegeder
Experinces with mechanical pre-treatment of horse-dung on a biogas plant
3rd IBBA workshop, in Malmö, Sweden, September 10th 2015
24
Mechanical pretreatment
Cognition
Significant influence on particle structure and - size
No significant effect on methane yield of green plant silage
Clearly significant effect for horse manure
Increasing of methane yield
Degradation kinetics
Optimal grinding effect at 15 s pretreatment
Energy consumption is depending on substrate type and
DM-content (10 - 20 kWh / t FM)
Mechanical desintegration only relevant for lignocellulosic material
Hans Oechsner and Matthias Mönch-Tegeder
Experinces with mechanical pre-treatment of horse-dung on a biogas plant
3rd IBBA workshop, in Malmö, Sweden, September 10th 2015
25
Examinations in practical scale
Too little experience with lignocellulosic materials in
practical plants:
Effects on process biology
Influence on substrate utilisation
Demand on process engineering
Necessity of pretreatment
Hans Oechsner and Matthias Mönch-Tegeder
Experinces with mechanical pre-treatment of horse-dung on a biogas plant
3rd IBBA workshop, in Malmö, Sweden, September 10th 2015
26
Usability of horse manure in practical scale
Research biogas plant „Unterer Lindenhof“
Electrical power: 186 kWel
Digestervolume: 800 m³ Netto
Temperature: 40.0 °C
Hans Oechsner and Matthias Mönch-Tegeder
Experinces with mechanical pre-treatment of horse-dung on a biogas plant
3rd IBBA workshop, in Malmö, Sweden, September 10th 2015
27
Usability of horse manure in practical scale
Research biogas plant „Unterer Lindenhof“
Period of investigation: 160 days
Use of Cross Flow Grinder MeWa Bio-QZ 900 at digester 1
Identical mass and ratio of feed in both digesters
Analyse of biological parameters
Continuously investigation of gasvolume and gas composition
Calculation of degradation efficiency
Methane yield of digestate with HBT
Calculation of methane yield by using of substrate input
Hans Oechsner and Matthias Mönch-Tegeder
Experinces with mechanical pre-treatment of horse-dung on a biogas plant
3rd IBBA workshop, in Malmö, Sweden, September 10th 2015
28
Usability of horse manure in practical scale
Ration of feed
Maize silage12%
Grass silage
8%
Whole plant silage10%
Crushed grains
3%
Horse manure
18%
Solid manure
8%
Liquid manure
41%
26 %
33 %Feed
amountHRT OLR
[t/d] [d] [kg/m³ d]
Digester 1
pretreated10.5 ± 2.0 78.8 ± 14.1 2.9 ± 0.5
Digester 2
control10.4 ± 2.3 79.5 ± 15.6 2.8 ± 0.6
Pretreatment at digester 1
Hans Oechsner and Matthias Mönch-Tegeder
Experinces with mechanical pre-treatment of horse-dung on a biogas plant
3rd IBBA workshop, in Malmö, Sweden, September 10th 2015
29
Horse manure in practical plant
With and without mechanical pretreatment
0
200
400
600
800
1000
1200
1400
1600
0 20 40 60 80 100 120 140 160
Bio
gas
yie
ldp
er
day
[Nm
³ /
d]
Duration
Fermenter 1 (Bio-QZ)
Fermenter 2(unaufbereitet)
with pretreatment
0.272 m³/kg VS
0.200 m³/kg VS
without pretreatment
Mönch-Tegeder, 2013
Hans Oechsner and Matthias Mönch-Tegeder
Experinces with mechanical pre-treatment of horse-dung on a biogas plant
3rd IBBA workshop, in Malmö, Sweden, September 10th 2015
30
Use of horse manure in practical scale
Degradation efficiency
0.306 0.272
0.200
0
0,05
0,1
0,15
0,2
0,25
0,3
0,35
Berechnet Fermenter 1 (Bio-QZ) Fermenter 2 (unaufbereitet)
Cu
mu
lati
vesp
eci
fic
met
han
eyi
eld
[Nm
³ /
kg V
S]
- 26.5 %
- 11.2 %
Calculation Digester 1 Digester 2
over HBT and input pretreated Control
standardized: 1013 hPa, 273,15 K
Hans Oechsner and Matthias Mönch-Tegeder
Experinces with mechanical pre-treatment of horse-dung on a biogas plant
3rd IBBA workshop, in Malmö, Sweden, September 10th 2015
31
Usability of horse manure in practical scale
Costs of pretreatment
Definition: investment 104,800 €; interest rate 5 %; machine life 8 a;
electricity consumption 11 kWh / t FM; electricity costs 20 ct / kWh ;
price of maize silage 40 € / t 31
186 kW
30 % liquid manure;
30 % horse manure;
40 % maize silage
30 % liquid manure;
50 % horse manure;
20 % maize silage
Total input t / d 16.5 17.9
Solid Input t / d 11.5 12.5
Input horse manure t / a 1,825 3,285
Amortisation € / a 15,720 15,720
Maintenance costs € / a 2,000 2,000
Electricity costs € / a 9,235 10,038
Pretreatment costs
of horse manure€ / t 14.8 8.4
Cost saving because
of maize substitution€ / a 24,150 67,150
Hans Oechsner and Matthias Mönch-Tegeder
Experinces with mechanical pre-treatment of horse-dung on a biogas plant
3rd IBBA workshop, in Malmö, Sweden, September 10th 2015
32
Usability of horse manure in practical scale
Cognition
Process biology
Stable operation (low concentration of VFA)
Increase of DM-content in digester (+3 %)
Substrate efficiency
Quality of horse manure is essential
Nearly complete utilisation of energy content with pretreatment
(89 %)
Insufficient degradation without pretreatment (65 %)
(In reference to HBT-yields)
Process engineering
Neither problems in digester 1 detected (with pretreatment)
Floating layer in digester 2 (without pretreatment)
Reduced demand of process heating (4.750 kWhth / month)
Energy consumption of Bio-QZ: 11,3 ± 1,3 kWhel / t FM, to allow
the use of a substrate, which yields > 300 kWh/t FM electric
energy
Hans Oechsner and Matthias Mönch-Tegeder
Experinces with mechanical pre-treatment of horse-dung on a biogas plant
3rd IBBA workshop, in Malmö, Sweden, September 10th 2015
33
Conclusions
Digestibility of horse manure
Horse manure with straw as litter can be well used as cosubstrate in
biogas plants
Quality of horse manure (composition and age) have a big influence on
biogas yield
Mechanical pretreatment
For the use of green plant silages, pretreatment has no positive effect
on digestibility and gas yield
For the use of fibrous substrates, pretreatment has a crucial effect on
gas yield and degradation kinetics
Usability of horse manure in practical biogas plants
Use of horse manure is only feasible with pretreatment
Substitution of 7.8 Mio t maize could be possible in Germany, if 50 % of
available horse manure is digested
156,000 ha is equivalent to 13 % of momentan used crop area for
biogas production
Extension of substrate spectrum possible
Hans Oechsner and Matthias Mönch-Tegeder
Experinces with mechanical pre-treatment of horse-dung on a biogas plant
3rd IBBA workshop, in Malmö, Sweden, September 10th 2015
34
Thank you for Your attention!
Contact:
Dr. Hans Oechsner
Tel. ++49 - 711 459 22683
Hans Oechsner and Matthias Mönch-Tegeder
Experinces with mechanical pre-treatment of horse-dung on a biogas plant
3rd IBBA workshop, in Malmö, Sweden, September 10th 2015
37
Daniel-Gromke et. al, 2013; Fachverband Biogas e.V., 2013; Gömann, 2013
Use of substrates in Biogas plants
7720 Full scale biogas plants in Germany
Substrate use about 115 Mio. t FM per year
10 % of arable land
Liquid manure38%
Solid manure5%
Biowaste and residues
4%
Maize silage39%
Grass silage5%
Whole plant silage
4%Other energy crops
5%
Energy crops53%