Confidential A European Project supported within the Seventh Framework Programme for Research and Technological Development Castro (LE), Italy, September 22nd 2011 Speaker : Alessandro Spagni (ENEA) EuroBioRef Summer School 18-24 Sep 2011 From lab scale to full scale biogas plants (R. Farina – A. Spagni)
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ConfidentialA European Project supported within the Seventh Framework Programme for Research and Technological Development
Castro (LE), Italy, September 22nd 2011Speaker : Alessandro Spagni (ENEA)
EuroBioRef Summer School 18-24 Sep 2011
From lab scale to full scale biogas plants(R. Farina – A. Spagni)
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Outline● General
● What can be used to used as substrate?
● Pretreatment
● Design criteria
● Reactor for biogas production from biomass
● Reactor for biogas production from wastewater
2
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Substrates
● Several substrates can be used:● Biomass● Energy crops●Waste●Wastewater● Biogas production can be designed as the “final
treatment” (or last step) in the biorefinery concept
● How can we evaluate the biogas potential?● The Biochemical methane potential
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Example of a biorefinery
Algae
biodisel Glycerin
H2
H2
CH4
CH4
MFC
OFMSW
wastes
biomass
PHA
Ethanol
Wastewater
H2
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Process and oxygen
● Respiration
● Anoxic respiration
422291918 NHO8H18COHO17.5NOHC
OHOHCONOHCHNO 2222
136
5
67
65
3
CH3COO- CH4 + CO2 .
● FermentationHCO3- + 4H2 CH4 + 2H2O + OH-
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Process and oxygen
● Aerobic condition● If oxygen is present
● Anoxic conditions● oxygen absent but other inorganic electron acceptors are
present● Anaerobic digestion
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Organic matter CO2+H2O
Synthesis New biomassGrowth
Energy
Bacterial cell
O2
Yield
1-Yield
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Kinetics: Growth and hydrolysis
9
Bs
XKS
SVV
max
Bhh XXsKr
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Kinetics and environmental conditions
● Aerobic microorganisms● Growth rate = 6 d-1● Yield up to 67%
● Anoxic● both 10-20% smaller than aerobic● Anaerobic
● Growth rate < 1 d-1● Yield up to 10%
● Hydrolysis: no big differences
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Kinetics and environmental conditions
● Methanogens are strictly anaerobic
● Competition
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Ammonia inhibitionAmmonia usually accumulates in the reactors
13
OHNHOHNH 3324
Sulphate reductionCompete for substrates
SHSSO 222
4
Not appropriate when sulphate conc is high
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75%
28%72%
23%52%
Organic matter
Acetogenic bacteria
Homoacetogenic bacteria
Lipids, Alchols, etc.
ACETATE H2 + CO2
Acetoclastic methanogenic
bacteria
Methanogenic
bacteria
CH4 + CO2 CH4 + H2O
carbohydratesproteins
lipids
5%20%
100%
Hydrolytic fermentative bacteria
Disintegration
Hydrolysis
Acidogenesi
Methanogenesis
Rat
e
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Several different microorganisms work togheter to produce methane
● Can we use pure cultures?●Substrate characteristics limits●Process limits
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Process conditions
● Temperature●Psychrophilic: no heating ●Mesophilic 35-37°C●Thermophilic 55°C
● pH● Nutrients?●Add micronutrients●Waste design
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Cumulative biogas production of methane and biogas at different temperatures
Different types of packing material for anaerobic filters
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Anaerobic granules scheme of UASB reactor
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UASB
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EGSB, expanded granular sludge bed
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Pilot-plantUASB
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Some comments about process management
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Ammonia concentration inside a reactor for methane production from biomass from the production of antibiotics (yeast waste)
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Biogas productivity (waste from antibiotics production)
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0
200
400
600
800
1000
1200
1400
1600
1800
2000
0 50 100 150 200
Biog
as (
mL/
gior
no)
giorni
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Membrane
69
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Membrane
70
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Membrane
71
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Biogas production using a membrane anaerobic reactor
72Time (d)0 50 100 150 200 250
Bio
gas
prod
uctio
n (L
/d)
0
10
20
30
40
50
60
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HR
T (d
)0
20406080
100120140
CO
D (g
/L)
051015202530
CODinCODout
Time (d)0 50 100 150 200 250
OLR
[gC
OD
/(L*d
)]
02468
10121416
(a)
(b)
(c)
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Time (d)0 50 100 150 200 250
CO
D re
mov
al (%
)
20
40
60
80
100
120
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Time (d)0 50 100 150 200 250
Vol
atile
fatty
aci
ds (g
/L)
0
2
4
6
8
10
12AceticPropionicn-butyric
Time (d)0 50 100 150 200 250
pH
5.5
6.0
6.5
7.0
7.5
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Anaerobic processes and wastewater treatment
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Biological hydrogen production via dark fermentation
78
75%
28%72%
23%52%
Organic matter
Acetogenic bacteria
Homoacetogenic bacteria
Lipids, Alchols, etc.
ACETATE H2 + CO2
Acetoclastic methanogenic
bacteria
Methanogenic
bacteria
CH4 + CO2 CH4 + H2O
carbohydratesproteins
lipids
5%20%
100%
Hydrolytic fermentative bacteria
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Select for H2 production● Thermal treatment of the inoculum
● pH
● HRT
● Reactor temperature
CSTR
VFABIOMASS
H2
VFA
BIOMASS
Heat
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H2 production Dark fermentation and anaerobic digestion
80
CSTR
VFA
H2
CSTR
CH4
Waste
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0 1 2 3 4 5 10 20 30 40 50 60 70 80
CG
P (L
/kgC
OD
)
050
100150200250300
BHP BMP
0 1 2 3 4 5 6 7 10 20 30 40 50 60
CG
P (L
/kgC
OD
)
050
100150200250300
H2 CH4
BMPBHP
0 1 2 3 4 5 6 7 10 20 30 40 50 60 70 80 90
CG
P (L
/kgC
OD
)
050
100150200250300
BHP BMP
a
b
c
0 1 2 3 4 5 6 7 10 20 30 40 50
CG
P (L
/kgC
OD
)
050
100150200250300
BHP BMP
Time (d)0 1 2 3 4 5 6 7 10 20 30 40 50
CG
P (L
/kgC
OD
)
050
100150200250300
BHP BMP
d
e
Cumulative gas production (CGP) with glucose (a), common wheat (b), durum wheat (c), mashed potato (d) and steam peeling potato (e) wastes.
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Biological hydrogen productionDark fermentation and photo-fermentation
82
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PHA
83
75%
28%72%
23%52%
Organic matter
Acetogenic bacteria
Homoacetogenic bacteria
Lipids, Alchols, etc.
ACETATE H2 + CO2
Acetoclastic methanogenic
bacteria
Methanogenic
bacteria
CH4 + CO2 CH4 + H2O
carbohydratesproteins
lipids
5%20%
100%
Hydrolytic fermentative bacteria
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PHA
● Some bacteria accumulate PHA from organic acids ● it happens when this is a competitive advantage● A nutrient limitation● Alternation of environmental conditions