Biological recycling and treatment processes
Transcript of Biological recycling and treatment processes
teach4waste I Mechanical-biological waste treatment I Slide 1
Biological recycling and treatment processes
- MBT
Klaus Fricke, Christiane Pereira, Andrea Pfeiffer and Bruno Aucar
teach4waste I Mechanical-biological waste treatment I Slide 2
Mechanical-biological waste treatment -learning objectives
The students should be able to:
• Understand the legal framework and its classification in
the waste hierarchy and to derive long-term perspectives
• Identify the objectives of the 5 main limit values from the
German Landfill Ordinance and draw conclusions for
process engineering
• Identify current and future requirements for the
performance of mechanical-biological pretreatment
processes prior to landfilling and integration of energy
recovery
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Recycling
Energy recovery
Avoidance
Inc
rea
se
of
GH
G c
red
its Preparation
for reuse
Re
so
urc
ee
ffic
ien
cy
Inc
rea
se
in G
HG
em
iss
ion
s
Pre-treatment prior to landfilling
Incineration and MBT
Disposal
Waste hierarchy in the EU and Germany
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Waste management objectives:
• Minimizing volume and mass of waste delivered to landfill
• Inactivation of biological processes → preventing landfill gas production and
settlement
• Immobilizing contaminants in the waste in order to reduce leachate emissions
• Separation of recyclable materials, Fe- and non-Fe-metals, plastics
• Production of alternative fuels e.g. RDF
Overall objectives:
Protection of
• Climate, water resources and soil
• Resources
Objectives of treatment before landfill
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Mechanical, biological and thermal processes
• *66 incineration plants1) 20.2 Mio. t/a
• *32 energy recovery plants2) 5.8 Mio. t/a
• **36 MBT 4.8 Mio. t/a
Waste treatment before landfill
- Suitable procedures
1) Grate combustion technologies only; 2) Grate combustion and fluidized bed technologies
(Sources: *Quicker et al., 2018; **Ketelsen, 2019)
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Parameter Reference Landfill class II
Incineration
plant
Landfill class
II
MBT
Ignition loss % in DM* 5
TOCsolid % in DM 3 18
TOCEluate mg/l 80 300
Respiration rate (AT4) mg O2/g DM 5
Gas formation rate (GB21) Nl/kg DM 20
Upper calorific value kJ/kg 6,000
*DM = Dry matter
Boundary values of DeponieV (German landfill ordinance) (2009)
Waste treatment before landfill
- Requirements for material to be landfilled
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Emission parameter:
- respiration rate (AT4) ≤ 5 mg/g DM or
- gas formation rate (GB21) ≤ 20 l/kg DM
- TOCEluate ≤ 300 mg/l
Utilisation parameter:
- upper calorific value: ≤ 6,000 kJ/kg or
- TOCsolid: ≤ 18 % DM
Low gas emissions
Low concentrations of organics and in-organics in leachate
Low concentrations of plastics, textiles and paper/cardboard
Targets of boundary values of MBT waste in Germany:
Legal background landfill
- Germany
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• Kitchen waste
• Food waste
• Sewage sludge
• Garden waste wood-free
• Wood
• Paper and cardboard
• Bio-based plastics
• Nappies
• Nativ textile
Carbonate
Water of
cristalisation
Plastic
Rubberi
Lether
Hemicellulose
Lignin
Huminic substances
Glucose
Starche
Protein
Fat
Cellulose
Lo
ss
of
ign
itio
n
ae
rob
ic
de
gra
da
lble
an
ae
rob
ic
de
gra
da
ble
Raw material product of organic substances MBT- Species differentiated by microbial availability
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Biological treatment
Anaerobic / aerobic
Municipal solid waste
Fe
Landfill
15 - 40%
HCF
5 – 8%
LVC >11 MJ/kg
Screening
100 mm Fe
> 100 mm
Reduction of oDM and H2O,
25 - 30%
> 30 - 40 mmScreening
30 – 40 mm
Sorting (optional) e.g.
• Plastic
• Paper/cardboard
• Glass
• Wood
• Textiles
< 100 mm
Filter material
MOL**
Shredding
Biogas
9 – 12%
Ferrous metals
2 – 3%
HCF*
20 – 35%
LVC >11 MJ/kg
MBT prior to landfill
- Flow chart, simplified
< 30 - 40 mm
Optional if anaerobic
digestion is integrated
*High Calorific Fraction
**Methane Oxidation Layer
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Mass reduction by
• Sorting out recyclables and alternative fuels
• Loss of biological degradation (H2O, CO2, Biogas)
• Loss of drying
MBT performance
- Mass reduction
0,0
0,2
0,4
0,6
0,8
1,0
MBT MBT + removal of recyclables
[t]
/RDF
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Higher installation density by
• Reduction of grain size through shredding and microbiological downsizing
• Separation of coarse grain fraction
• Separation of elastic waste components like plastics
Installation density on landfill
0,7
MBT performance
- Volume reduction on landfill by increasing density
0,7
0,9
1,3
0,0
0,2
0,4
0,6
0,8
1,0
1,2
1,4
Installation with caterpillar Installation withcompactor (thin layer)
lowly compacted
MBT material; installationwith compactor; thin layer;
highly compacted
[t/m³] Installation (bulk) density on landfill
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MBT performance
- Need for reduction of volume on landfill
0,0
0,2
0,4
0,6
0,8
1,0
1,2
Untreated MBT (40% massreduktion)
MBT + removal ofrecyclables (70% mass
reduction)
[m³/t]
Required landfill volume per t waste
Compared to untreated waste, the demand for landfill capacity is lower by
58 up to 79 %
1,1
0,23
0,46
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MBT performance- Reduction of gas potential
0
20
40
60
80
100
120
140
160
180
200
220
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19
Duration of treatment (weeks)
GB
21
(l/k
g d
m)
lower area
upper area
Limit value
20
Reduction of gas potential by aerobic treatment
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MBT performance
- Reduction of landfill gas emission
MBT gas reduction rate 80 % !!
Reduction of landfill gas emission
200
40 40
50
100
150
200
250
MSW untreated MBT material MBT material +methane oxidation
[Nl/
kg
wa
ste
]
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MBT performance
- Reduction of DOC
0
500
1000
1500
2000
2500
3000
3500
4000
0 2 4 6 8 10 12 14 16 18 20 22 24 26
Duration of treatment (weeks)
DO
C-E
luat
(mg
/l)
lower area
upper area
300
Limit Value
Reduction of DOC during aerobic treatment
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MBT performance
- Leachate emission (quantity)
0
10
20
30
40
50
60
70
80
Caterpillar Compactor
Le
ac
ha
teg
en
era
tio
n [
% o
f to
t. p
rec
ipit
ati
on
] Base
runoff
Base
runoff
Base
runoff
Compactor
after MBTuntreated waste
Surface
runoff
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0
5000
10000
15000
20000
25000
30000
35000
40000
COD BOD5
COD BOD5
CODBOD5
MBT materialFresh waste
starting phase
Fresh waste
methane phase
[Nl/
kg
]
after MBTuntreated waste
MBT performance
- Leachate emission (quality)
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Biological treatment
Anaerobic / aerobic
Municipal solid waste
Fe
Landfill
15 - 40%
HCF
5 – 8%
LVC < 11 MJ/kg
Screening
100 mm Fe
> 100 mm
Reduction of oDM and H2O,
25 - 30%
> 30 - 40 mmScreening
30 – 40 mm
Sorting (optional) e.g.
• Plastic
• Paper/cardboard
• Glass
• Wood
• Textiles
< 100 mm
Filter material
MOL*
Shredding
Biogas
9 – 12%
Ferrous metals
2 – 3%
HCF
20 – 38%
LVC < 11 MJ/kg
MBT prior to landfill
- Flow chart, simplified
< 30 - 40 mm
Optional if anaerobic
digestion is integrated
* Methane oxidation layer
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Methane oxidation layer
(Source: Scheutz et al., 2009)
Me
tha
ne
ox
ida
tion
laye
r
> 1
20
cm
Gas diffusion
layer
Landfill body top
layer preferably
uncompressed
MBT output
- Methane oxidation layer (MOL)
Biological methane oxidation with methanotrophic bacteria
CH4 + 2O2 → CO2 + 2H2O + biomass + 210.8 kcal/mol
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Efficiency of MBT treatment and methane oxidation layer
Landfill gas - Reduction rates
200
40 40
50
100
150
200
250
MSW untreated MBT material MBT material +methane oxidation
[Nl/
kg
wa
ste
]
MBT and MOL gas reduction rate 98 % !!
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40 °
56 °
sgs engineers
Reduction of slope stability
screening to < 60 mm leeds to reduction of reinforcing material (fibres) from > 25 %
(w/w) to < 5 %(w/w)
reduction of tensile strength
Reason:
plastics are able to take up tensile forces
18 °
3.01.0
MBT performance
- Slope stability
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Consequences for construction:
• as a result of the homogeneity of MBT material
large differences in settlement are not to be
expected
• final surface sealing system can be installed
earlier
• Higher viability of surface sealing system
Total settlement MBT
[%]
Untreated waste
[%]
- primary settlement (load) 15 - 20 35 - 50
- secondary settlement (biol. processes) < 5 15 - 30
MBT performance
- Surface settlement
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MBT landfill operation- Emplacement technologies
For distribution: bulldozer / tracked loaders
For compaction: - compactor
- pad foot roller
- and vibrating smooth roller
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Aftercare
- Period of time and costs
MBT Landfill MBT Landfill
• Gas collection not necessary
• Shorter period of time for leachate collection and treatment
Period of aftercare of untreated waste > 30 years
Period of aftercare of MBT pre-treated waste < 30 years
Lower costs of aftercare
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Generation of fuels from waste in MBT - Increasing the calorific value through drying
0
5.000
10.000
15.000
20.000
25.000
30% 40% 50% 60% 70% 80%DM-content
Lower calorific value
Ho* paper 15.500 16.500 17.500 Ho cardboard 17,500 19.000 20.500 Ho diapers 23.000 27.300 31.000
kJ/kg DM
*upper calorific value
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Dryers - Overview technologies
Thermal dryers
• disc dryer
• paddle dryer
• thin film dryer
Thermal dryers
• drum dryers
• fluid bed dryer
• belt dryers
• ascending pipe dryer
Convection
dryer
Conduction
dryer
Solar
dryers
Solar dryers,
combination of solar
dryers with
supporting heat
supply
Aerobic
dryer
Aerobic dryer,
combination aerobic
dryer with
supporting heat
supply
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Air temperature 30 °C
30 g H2O/m3 air
Air temperature 50 °C
82 g H2O/m3 air
Drying - Aerobic drying
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…increases the quality of separation processes:
• Screens
• Air classifier
• Ballistic separator…improves the product
quality
Pre-processing / waste treatment - Water content and processing properties
Low water content reduces adhesive effects (protein) between waste particles...
teach4waste I Mechanical-biological waste treatment I Slide 31
• MBT is based on existing and well known technology, like mechanical treatment
stages, composting, aerobic drying, fermentation
• MBT is a fairly flexible system approach which can be adjusted to local
conditions and treatment targets
• Because of the dynamic development of waste amount, waste composition and
the recycling markets, the recycling and treatment technology has to be highly
adaptable. This flexibility can be achieved by MBT due to:
- Its ability for modular construction, therefore easily adaptable in size
- High flexibility of treatment goals, therefore adjustments resulting from
changes in markets and demand are possible
Key Advantages of MBT
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• MBT can be adjusted in order to optimise the energy yield from waste, including
the production of renewable energy via AD and heat and power via RDF
combustion
• Recyclable materials like plastics, paper or glass can be separated with
automatic and/or manual sorting systems
• MBT reduces the waste volume - this minimizes the demand for landfill capacity
which maximises the landfill’s resource and lifespan
• GHG mitigation in a very large scope is possible. Compared to other GHG
mitigation options, its costs are relatively low
Key Advantages of MBT
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Lessons learned
• Name the objectives of the pre-treatment of residual waste
• Explain limit values and their respective protection objectives
• How are those being implemented by the MBT technology?
• Which are the different concepts of MBT? Draw a process flow with the most
important process steps
• Which are the objectives of drying waste?
• Which biological type of drying waste exists? On which physical basic principle is
it based?
• Sample calculation
• Which products and material streams are being discharged by the MBT?
• Explain the climate effect of landfilling untreated and treated waste - both
thermical and mechanical-biological