Upload
others
View
14
Download
0
Embed Size (px)
Citation preview
Technical digestate treatment- advantages, limitations, costs -
Biogaz Europe, Nantes, 25. and 26.10.2011
Helmut Döhler, Sebastian Wulf
Biogaz Europe, Nantes, 25. and 26.10.2011
• Aims of digestate treatment and operating principles
• Treatment Techniques and Model Biogas Plant
• Costs of treatment technologies
• Comparative assessment
• Pilot project Italy
• Conclusions
Content
Introduction
Technologies
Products
Comparitiveassessment
Pilot project
Conclusions
Reasons for digestate treatment
• „Export“ of nutrients
• Reduced costs of storage and application
• Production of a tradeable fertilizer– storable and transportable fertilizers
• Reduction of environmental effects– Improved nutrient utilization– Reduced gaseous emissions– Odour reduction– Inactivation of pathogenes and weed seeds
Nach Weiland, KTBL 2001, verändert
Introduction
Technologies
Products
Comparitiveassessment
Pilot project
Conclusions
treatment technologies
physical chemical biological
separation
drying
evaporation
membranetechnologies
flocculation
precipitation
composting
nitrification /
denitrification
stripping
Elimination of nutrients
Principles of digestate treatment
Introduction
Technologies
Products
Comparitiveassessment
Pilot project
Conclusions
Model biogas plant
CHP (500 kWel / 650 kWth)
treatment
50 % cattle slurry50 % maize silage
Output: 20.000 m³ digestate
DM Ntot NH4-N P2O5 K2O [%] [g/kg]
7,75% 5,6 3,6 2,1 6,17
application to arable land in vincinity of biogas plant
(330 ha)
distant to biogas plant (20 km)
Introduction
Technologies
Products
Comparitiveassessment
Pilot project
Conclusions
Treatment 1 - Application (and storage)
Introduction
Technologies
Products
Comparitiveassessment
Pilot project
Conclusions
Treatment 2 – Separation and application
Foto: Ahrens, FAL
Introduction
Technologies
Products
Comparitiveassessment
Pilot project
Conclusions
! Separation is precondition for all following treatment technologies
separation(press-screw separator)
solid phase
(2.500 t/a) approx. 30% DM
liquid phase
(17.500 t/a )
biogas-plant
biogas
(20.000 t/a)substrate
Treatment 2 – Separation and application
Introduction
Technologies
Products
Comparitiveassessment
Pilot project
Conclusions
Treatment 3 – Drying
Foto: Ahrens, FAL
Introduction
Technologies
Products
Comparitiveassessment
Pilot project
Conclusions
separation(press-screw separator)
dried solid phase
(920 t/a) approx. 80% DM
liquid phase
(17.500 t/a )
biogas-plant
biogas
(20.000 t/a)substrate
drying of solid phase
exhaust air
Treatment 3 – Drying
Introduction
Technologies
Products
Comparitiveassessment
Pilot project
Conclusions
Spectrum of filtration techniques
Treatment 4 – Membrane technology
Introduction
Technologies
Products
Comparitiveassessment
Pilot project
Conclusions
ultrafiltration(UF)
Flocculationadditive
separation(decanter) shaking
screen
solid phase
(3.900 t/a)
concentrate
(5.000 t/a)
reverse osmosis (RO)
antiscalantacid
concentrate - recirculation
permeatedirect discharging
quality
(8.700 t/a)
biogas-plant
biogas
substrate
Treatment 4 – Membrane technology
Introduction
Technologies
Products
Comparitiveassessment
Pilot project
Conclusions recirculation
Treatment 5 – Evaporation
separation(press-screw separator)
solid phase
(3.900 t/a)
concentrate
(6.100 t/a)
evaporation plant- two-stage -
acid
condensate
(10.000 t/a )
biogas-plant
biogas
(20.000 t/a)substrate
(Photo: www.guetling.com)
Introduction
Technologies
Products
Comparitiveassessment
Pilot project
Conclusions
Treatment 6 – Stripping
separation(press-screw separator)
solid phase
(2.500 t/a)
ASS
(650 t/a)
NH3-strippingwaste water
(14.200 t/a )
biogas-plant
biogas
(20.000 t/a)substrate
P-precipitation
(optional)
P-K- sludge
(2.900 t/a)
Introduction
Technologies
Products
Comparitiveassessment
Pilot project
Conclusions
nutrient concentrations in treatment products
0
5
10
15
20
25
30
35
40
45
50
liq
uid
so
lid
liq
uid
so
lid
liq
uid
so
lid
liq
uid
so
lid
liq
uid
so
lid
liq
uid
nu
trie
nts
[k
g/
t]
Norg NH4-N P2O5 K2O
applicationseparation
belt dryermembrane
evaporationstripping
80,6 kg/tIntroduction
Technologies
Products
Comparitiveassessment
Pilot project
Conclusions
0%
20%
40%
60%
80%
100%
application separation belt dryer belt dryer(100% heat)
membranetechnique
evaporation stripping
digestate solid phase liquid phase / concentrateprocess water dischargable water/ air
Mass balance of products
Introduction
Technologies
Products
Comparitiveassessment
Pilot project
Conclusions
1,50 2,003,84 3,81
5,864,55 5,25
0,360,41
0,77 0,91
2,08
1,551,382,57
3,48
4,501,84
0,82
1,47
0,66
2,012,24
2,112,06 1,47
1,34
1,36
2,362,35
2,232,11 1,62
1,41
0,70
-4,40 -4,40 -4,26 -4,08 -4,40 -4,40 -4,38
-9
-5
-1
3
7
11
15
application separation belt dryer belt dryer100%
membranetechnology
evaporation stripping
€/m
3 dig
es
tate
fix costs energy (el.) energy (th.) consumables application
transport nutrients heat bonus net costs
Specific costs of treatment
Introduction
Technologies
Products
Comparitiveassessment
Pilot project
Conclusions
1,84 2,59
7,268,29 7,46
10,52
6,81
-9
-5
-1
3
7
11
15
application separation belt dryer belt dryer100%
membranetechnology
evaporation stripping
€/m
3 dig
es
tate
fix costs energy (el.) energy (th.) consumables application
transport nutrients heat bonus net costs
Specific costs of treatment
Introduction
Technologies
Products
Comparitiveassessment
Pilot project
Conclusions
5,623,66 2,95
-9
-5
-1
3
7
11
20.000 40.000 80.000 20.000 40.000 80.000
€/m
3 dig
es
tate
fix costs energy (el.) energy (th.) consumables application
transport nutrients heat bonus net costs
Specific costs of treatment – effect of plant size
Introduction
Technologies
Products
Comparitiveassessment
Pilot project
Conclusions
Without treatment Membrane technology
Pilot project Italy
Introduction
Technologies
Products& Costs
Conclusions
Pilot project Italy
Introduction
Technologies
Products& Costs
ConclusionsSeparation (decanter and srew press)
Ultrafiltration
Reverse Osmosis
Zeolite Filter
Ammonia Stripping
Drying
Pilot project Italy
Introduction
Technologies
Products& Costs
Conclusions
Summary and Conclusions- technical aspects -
• separation is without technical risks
- no reduction of residue volume for application
costs of application is increased
only useful in case of local need
• drying of solid phase
- well established in other fields of application
- adaptation to digestate drying is well advanced
- profitable pathways of utilization for dried product arenecessary
Introduction
Technologies
Products
Comparitiveassessment
Pilot project
Conclusions
- complete use of heat bonus can make drying profitable(only if no other option of heat use)
• Membrane technologies are furthest advanced
• Treatment technologies for liquid phase are not „state of theart“ yet
- challenge: reduction of energy demand and wear-out
- several reference plants
• Evaporation and stripping not so far advanced in permanent operation
- Pilot plants are in implementation
- profound assessment of reliability a.profitabilitynot yet possible
- technical risks still high
Summary and Conclusions- technical aspects -
Introduction
Technologies
Products& Costs
Comparitiveassessment
Pilot project
Conclusions
• Cost efficiency strongly depends on conditions of biogas plant
Treatment can be useful:
- in areas with high nutrient surplusses
- for large biogas plants
- in areas focussing on living and recreational quality
- if there is a (also local) market for treatment products
Summary and Conclusions-
Introduction
Technologies
Products
Comparitiveassessment
Pilot project
Conclusions
Technical digestate treatment- advantages, limitations, costs -
Biogaz Europe, Nantes, 25. and 26.10.2011
Helmut Döhler, Sebastian Wulf
Biogaz Europe, Nantes, 25. and 26.10.2011
Merci beaucoup pour votre attention !
Thank you for your kind attention !
Vielen Dank für Ihre Aufmerksamkeit !