TRENDS AND PERSPECTIVES FOR ANAEROBIC DIGESTION: AN OVERVIEW
LUC DE BAERELUC DE BAEREORGANIC WASTE SYSTEMS
ISWA BEACON CONFERENCE: ‘THE GLOBAL CHALLENGE: OPTIMISING THE C-CYCLE’
PERUGIA, ITALY, MAY 22-23, 2008
ADVANTAGES OF ANAEROBIC DIGESTION OF SOLID WASTE
• PRODUCTION OF RENEWABLE ENERGY(60 TO 100 M³ OF METHANE/TON)
• RECOVERY OF ORGANIC MATTER AS COMPOST
• 200 TIMES LESS ODOURS THAN AEROBIC COMPOSTINGCOMPOSTING
• 20 TO 40% OF SURFACE AREA NEEDED FOR AEROBIC COMPOSTING: EASY TO INSERT
• HIGH PUBLIC ACCEPTANCE
WHAT IS THE STATE OF THE ARTOF ANAEROBIC DIGESTION
OF THE ORGANIC FRACTION OF MUNICIPAL SOLID WASTE
IN EUROPE?IN EUROPE?
DETERMINATION OF CAPACITY
CRITERIA
• HOUSEHOLD ORGANIC WASTE OR EQUIVALENT
• MORE THAN 10% HOUSEHOLD ORGANIC SOLID WASTE
• > 3000 T PER YEAR MINIMUM SIZE
• DESIGN CAPACITY USED UNLESS SPECIFIED • DESIGN CAPACITY USED UNLESS SPECIFIED OTHERWISE
• TOTAL CAPACITY FOR BIOWASTE, BUT ONLY DIGESTION CAPACITY FOR RESIDUAL WASTE
• PLANTS NOT ELIMINATED IF OPERATION STOPPED
• PLANTS AT LEAST UNDER CONSTRUCTION(ONLY PROGNOSIS FOR YEAR 2009-2010)
CAPACITY IN EUROPE
• 171 PLANTS IDENTIFIED IN 17 EUROPEAN COUNTRIES
• 5.204.000 T/YEAR CAPACITY IN 2010
• CAPACITY DEVELOPMENTPERIOD INCREASE AVERAGE SIZE PLANTS/YEARPERIOD INCREASE AVERAGE SIZE PLANTS/YEAR
91 - 95 39 KT/Y 13 KT/Y 3 96 - 00 224 KT/Y 25.4 KT/Y 8.8 01 - 05 415 KT/Y 38.5 KT/Y 10.806 - 10 346 KT/Y 31.4 KT/Y 11
CUMULATIVE CAPACITY
3.000
4.000
5.000
6.000
Inst
alle
d C
apac
ity (
kTO
N)/
y)
15
20
25
30
35
Average size plants (kTO
N/y)
Anual capacity
Cumulative Capacity
Cumulative AverageCapacity
0
1.000
2.000
till 19
90 91 92 93 94 95 96 97 98 9920
0020
0120
0220
0320
0420
0520
0620
0720
08>20
09
Inst
alle
d C
apac
ity (
kTO
N)/
y)
0
5
10
15
Average size plants (kTO
N/y)
FACTORS STIMULATING GROWTH IN CAPACITY
• LANDFILL DIRECTIVE AND RENEWABLE ELECTRICITY
• HIGH PRICE FOR OIL AND AGRICULTURAL CROPS MAY PLAY MORE OF A ROLE IN COMING YEARS
• IMPACT ENERGY PRICE LARGER FOR CLEAN • IMPACT ENERGY PRICE LARGER FOR CLEAN INDUSTRIAL ORGANICS THAN FOR HOUSEHOLD WASTE ORGANICS
• REVAMPING EXISTING COMPOSTING INSTALLATIONS (GROWTH FOR BIOWASTE DIGESTION, POSSIBLE GROWTH FOR RESIDUAL WASTE DIGESTION IN APPROXIMATELY 5 YEARS)
FACTORS HAMPERING GROWTH IN CAPACITY
• HYGIENIZATION REQUIREMENTS: NOT ONLY HIGH TEMPERATURE TREATMENT BUT ALSO SEPARATION NONHYGIENIZED/HYGIENIZED
• AIR EMISSION REQUIREMENTS: - RTO ON DIRTY AIR- RTO ON DIRTY AIR- LOW ODOR LEVELS
• STILL HIGHER COST THAN IN-VESSEL-COMPOSTING UNITS
CAPACITY PER COUNTRY
800.000
1.000.000
1.200.000
1.400.000
1.600.000
1.800.000
Inst
alle
d C
apac
ity (
t/y)
40.000
50.000
60.000
70.000
80.000
Total Capacity
Average Capacity
0
200.000
400.000
600.000
800.000
GERMANY
SPAINFRANCE
ITALY NL UK
SWIT
ZERLA
NDBELGIU
MPORTUGAL
AUSTRIASW
EDENM
alta
Luxe
mbu
rgNorw
ayDenm
ark
POLAND
FINLA
ND
Inst
alle
d C
apac
ity (
t/y)
0
10.000
20.000
30.000
ANALYSIS OF INSTALLED CAPACITY
•••• MESOPHILIC (35 - 40 °C) VERSUS THERMOPHILIC (50 - 55°C)
•••• DRY (> 15 % DS) VERSUS WET (< 15 % DS)
•••• TWO PHASE (ACIDIFICATION + METHANIZATION)
VERSUS SINGLE PHASE (COMBINED)VERSUS SINGLE PHASE (COMBINED)
•••• CODIGESTION (SOLID WASTE + OTHER SUBSTRATE)
VERSUS SOLID WASTE DIGESTION (ONLY WASTE)
•••• MIXED OR RESIDUAL WASTE (NO SEPARATE
COLLECTION) VERSUS BIOWASTE
(SEPARATE COLLECTION OF ORGANICS)
MESOPHILIC VERSUS THERMOPHILIC
2.000
2.500
3.000
3.500
4.000
Cum
ulat
ive
(kT
ON
/y)
50%
60%
70%
80%
90%
100%
MESO
THERMO
%MESO
0
500
1.000
1.500
till 19
90 91 92 93 94 95 96 97 98 9920
0020
0120
0220
0320
0420
0520
0620
0720
08>20
09
Cum
ulat
ive
(kT
ON
/y)
0%
10%
20%
30%
40%%MESO
%THERMO
MESOPHILIC VERSUS THERMOPHILIC
• 69% MESOPHILIC VS 31% THERMOPHILIC IN 2010
• 95% OF THERMOPHILIC PLANTS ARE DRY FERMENTATION
• ONLY 1 DRY CONTINUOUS SYSTEM OPERATES MOSTLY MESOPHILICALLY
• DRY BATCH SYSTEMS ALSO OPERATE IN MESOPHILIC TEMPERATURE RANGE
MESOPHILIC VERSUS THERMOPHILIC
MESO VS THERMO 1991 – 1995 1996 – 2000 2001 – 2005 2006 - 2010
% MESOPHILIC 64 64 80 59
• FIVE YEAR DEVELOPMENT OF CAPACITY
% MESOPHILIC
% THERMOPHILIC
64
36
64
36
80
20
59
41
WET VERSUS DRY
2.000
2.500
3.000
3.500
Cum
ulat
ive
(kT
ON
/y)
40%
50%
60%
70%
0
500
1.000
1.500
till 1
990 91 92 93 94 95 96 97 98 9920
0020
0120
0220
0320
0420
0520
0620
0720
08>20
09
Cum
ulat
ive
(kT
ON
/y)
0%
10%
20%
30%WET
DRY
%WET
%DRY
WET VERSUS DRY
• DRY 57% , WET 43% IN 2010
WET VS DRY 1991 – 1995 1996 – 2000 2001 – 2005 2006 - 2010
• FIVE YEAR DEVELOPMENT OF CAPACITY
% WET
% DRY
37
63
38
62
59
41
29
71
ONE VERSUS TWO-PHASE
2.500.000
3.000.000
3.500.000
4.000.000
4.500.000
5.000.000
Cum
ulat
ive
(t/y)
50%
60%
70%
80%
90%
100%
ONE CUMULATIVE
TWO CUMULATIVE
%ONE
0
500.000
1.000.000
1.500.000
2.000.000
till 1
990 91 92 93 94 95 96 97 98 9920
0020
0120
0220
0320
0420
0520
0620
0720
11>20
09
Cum
ulat
ive
(t/y)
0%
10%
20%
30%
40%%TWO
ONE VERSUS TWO-PHASE
• 93% ONE-PHASE VS 7% TWO-PHASE BY 2010
• FULL-SCALE PERCOLATION SYSTEMS WERE CONSTRUCTED (CONSIDERED TWO-PHASE SYSTEMS) IN 2000-2005, BUT NO MORE IN 2006-2010 EXCEPT FOR BATCH SYSTEMS2010 EXCEPT FOR BATCH SYSTEMS
• SOME BATCH SYSTEMS HAVE TWO METHANOGENIC PHASES
ONE VERSUS TWO-PHASE
SINGLE VS TWO PHASE
1991 – 1995 1996 – 2000 2001 – 2005 2006 - 2010
% SINGLE 85 91 92 98
• FIVE YEAR DEVELOPMENT OF CAPACITY
% SINGLE
% TWO PHASE
85
15
91
9
92
8
98
2
SINGLE FEEDSTOCK VERSUS CODIGESTION
2.000
2.500
3.000
3.500
4.000
4.500
5.000
Cum
ulat
ive
(kT
ON
/y)
40%
50%
60%
70%
80%
90%
100%
SOLID WASTE
CODIGESTION
% Solid Waste
% Codigestion
0
500
1.000
1.500
2.000
till 1
990 91 92 93 94 95 96 97 98 9920
0020
0120
0220
0320
0420
0520
0620
0720
08>20
09
Cum
ulat
ive
(kT
ON
/y)
0%
10%
20%
30%
40%% Codigestion
SINGLE FEEDSTOCK VERSUS CODIGESTION
• 92% ONLY SOLID WASTE VS 8% CODIGESTION BY
2010
• CODIGESTION WITH ENERGY CROPS (CORN) BUT LIMITED SO FAR
• MANY ENERGY CROP DIGESTION PLANTS ARE LOOKING FOR ORGANIC WASTE TO REPLACE EXPENSIVE CROPS, BUT ‘WASTE TREATMENT’ COMPLICATES THE PROJECTS SUBSTANTIALLY
SINGLE FEEDSTOCK VERSUS CODIGESTION
SOLID WASTE VS CODIGESTION
1991 – 1995 1996 – 2000 2001 – 2005 2006 - 2010
• FIVE YEAR DEVELOPMENT OF CAPACITY
% ONLY SOLID WASTE
% CODIGESTION
77
23
90
10
90
10
95
5
BIOWASTE VERSUS RESIDUAL WASTE
1.500
2.000
2.500
3.000
Cum
ulat
ive
(kT
:y)
50%
60%
70%
80%
90%
100%
BIOWASTE
RESIDUAL
%BIOWASTE
%RESIDUAL
0
500
1.000
1.500
till 1
990 91 92 93 94 95 96 97 98 9920
0020
0120
0220
0320
0420
0520
0620
0720
08>20
09
Cum
ulat
ive
(kT
:y)
0%
10%
20%
30%
40%
50%
BIOWASTE VERSUS RESIDUAL WASTE
• IN 1998: 87% BIOWASTE VS 13% RESIDUAL WASTE
• IN 2010: 52% BIOWASTE VS 48% RESIDUAL WASTE
• FIVE YEAR DEVELOPMENT OF CAPACITY
BIOWASTE VS 1991 – 1995 1996 – 2000 2001 – 2005 2006 - 2010BIOWASTE VS RESIDUAL
1991 – 1995 1996 – 2000 2001 – 2005 2006 - 2010
% BIOWASTE
% RESIDUAL
92
8
72
28
41
59
49
51
DIVERSITY IN APPLICATION
• MIXED WASTE + BIOWASTE + RESIDUAL WASTE
• RESTAURANT WASTE - CORN - INDUSTRIAL
ORGANICS AS ADDITIONAL FEEDSTOCKS
• MIXED/RESIDUAL WASTE: PARTIAL STREAM
DIGESTION (20 TO 70% OF ORGANICS) AND FULL
STREAM DIGESTION (100% OF ORGANICS)
DIGESTION CAN BE INSERTED INTO EXISTING COMPOSTING SITES
EXPANSION OF EXISTING COMPOSTING SITES
• MANY COMPOSTING SITES HAVE MORE WASTE BUT SITES HAVE NO ROOM FOR ADDITIONAL COMPOSTING AREA
• INSERTION OF PARTIAL STREAM ANAEROBIC DIGESTION CAN INCREASE EXISTING CAPACITY BY DIGESTION CAN INCREASE EXISTING CAPACITY BY UP TO 50% WITH MINIMAL SURFACE REQUIREMENT
• ECONOMICALLY VERY ATTRACTIVE
• WATER BALANCE IS CRUCIAL
CASE STUDY: INSERTION OF PARTIAL STREAM DIGESTION INTO EXISTING AEROBIC PLANT
• EXISTING AEROBIC COMPOSTING FACILITY
• CURRENT CAPACITY: 60.000 TPY OF BIOWASTE
• LOOKING FOR OPPORTUNITIES: COSTS, CAPACITY,…
• INSERTION OF AD PLANT FOR 40.000 TPY THROUGH PARTIAL STREAM DIGESTION
• USE OF EXISTING EQUIPMENT FOR AEROBIC TREATMENT
���� CONSEQUENCES?
CASE STUDY: LAYOUT SITE
190 m
90 m
35 mANAEROBIC DIGESTION0,2 ha
AEROBIC
125 mCOMPOSTING
2,4 ha
CASE STUDY: NEW PROCESS SCHEME
Biogas
GAS STORAGEDRANCO-
DIGESTER
2.600 m³
BiowasteFLARE
(<40 mm)
SIEVE
ENGINES Electricty (1.150 kW)
Heat (>40 mm)
(1.150 kW)
41
1 2 3
Tons/year 90.000 40.000 800
SteamDOSING UNIT
MIXING UNIT/ FEEDING PUMP
(<40 mm)
Existing aerobic composting
Heat
MIXER
(1.150 kW)
2
3
5
6
4 5 6
6.575 34.225 50.000
7
7
84.225
CASE STUDY: RESULTS
• NEW SITE CAPACITY = ca. 90.000 TON PER YEAR (DEPENDING ON TOTAL SOLIDS CONTENT OF THE SUBSTRATE)
• AD ON ONLY 10% OF THE SURFACE AREA OF THE AEROBIC COMPOSTING INCREASES SITE CAPACITY WITH ABOUT 50%
• AD PLANT PRODUCES ENOUGH ENERGY FOR THE WHOLE SITE
• DESPITE HIGHER CAPACITY, ODOR EMISSIONS ARE LOWER
• NET PROFIT OF AD PLANT POSSIBLE, DEPENDING ON LOCAL REVENUES FOR GREEN POWER OR ENERGY PRICES.
DIGESTION CAN BE COMBINED WITH DRYING USING WASTE HEAT OF ENGINES
SHREDDER
ROTATING
GAS STORAGEDRANCO
DIGESTER
Biowaste BiogasFLARE
> 60ElectricityGAS ENGINES
-Treatment of biowaste without wastewater productio n -
FLOW SCHEME DRANCO PLANT LEONBERG (GERMANY)
ROTATINGSIEVE
MAGNET
MAGNET
SHREDDER
DOSING UNIT FEEDINGPUMP
DRYERAEROBIC
COMPOSTING
2.440 m³
Residue
< 60
Overflow
ElectricityGAS ENGINES
Heat
Heat
Compost
DRANCO PLANT LEONBERG
750
1,000
1,250
1,500T
ON
S
150
200
250
300
Nm
³ BIO
GA
S/T
ON
INP
UT
0
250
500
50 1 5 9 13 17 21 25 29 33 37 41 45 49 4 8 12 16 20 24 28 32 36 40 44 48 52 3 7 11 15 19 23 27 31 35 39 43 47 51 2
WEEK (end 2004 - start 2008)
TO
NS
0
50
100
Nm
³ BIO
GA
S/T
ON
INP
UT
INPUT IN REACTOR BIOGAS PRODUCTION AVERAGE BIOGAS PRODUCTION PER YEAR
DRANCO INSTALLATION IN LEONBERG
DRYER
SOLID WASTE DIGESTION TECHNIQUES ARE BEING UTILIZED FOR ENERGY CROPS
WITH WASTE HEAT RECOVERY
HORIZONTAL WASTE DIGESTER: BIOWASTE+CROPS
HORIZONTAL DIGESTER WITH HEAT RECOVERY
VERTICAL WASTE DIGESTER WASTE FOR CROPS
SOLID WASTE DIGESTION APPLIED TO ENERGY CROPS WITH HEAT RECOVERY
TOTAL DIGESTER INPUT & ELECTRICITY PRODUCTION- DRANCO-FARM PLANT NÜSTEDT -
200
240
280
320
360
400
Ton
s
50,000
60,000
70,000
80,000
90,000
100,000
kWh electricity
0
40
80
120
160
200
1 3 5 7 9 11 13 15 17 19 21 23 25 27 29 31 33 35 37 39 41 43 45 47 49 51
Week
Ton
s
0
10,000
20,000
30,000
40,000
50,000
kWh electricity
TOTAL INPUT IN DIGESTER kWh PRODUCED MAX kWh (PERMIT)
• INCREASE IN 2006-2008
(NO INCREASE SINCE 1996)
• SO FAR LIMITED TO BIOWASTE
BATCH DIGESTION SYSTEMS
• SINGLE PHASE AND TWO-PHASE SYSTEMS
• LESS INVESTMENT AND MAINTENANCE
(BUT ALSO LESS RECOVERY)
• MORE WET ORGANIC INDUSTRIAL FEEDSTOCKS
• MORE EASY TO INTEGRATE WITH
WET ENERGY CROP PLANTS
WET DIGESTION
• GROWTH CONTINUES AT THE SAME PACE AS BEFORE
(ABOUT 11 PLANTS PER YEAR WITH AVERAGE SIZE OF 3500 0 T/Y)
• BATCH DIGESTION SYSTEMS REACTIVATED IN 2006-2008
• INSERTION OF BIOWASTE DIGESTION PLANTS
IN EXISTING COMPOSTING PLANTS
CONCLUSIONS
IN EXISTING COMPOSTING PLANTS
• CONTINUED GROWTH IN FRANCE AND UK FOR MIXED WASTE
• FURTHER EXTENSION INTO OTHER COUNTRIES
HOW ABOUT ITALY?