Biology of composting 07.11.2012, Tartu (Estonia)
jf, FiBL, CH-Frick 1
Research Institute of Organic AgricultureForschungsinstitut für biologischen Landbau
Biology of composting
Jacques Fuchs ([email protected])
Institut de recherche de l’agriculture biologique
www.fibl.org Introduction to composting and anaerobic digestion, Tartu, Nov. 2012, jf
Introduction to composting and anaerobic digestion
› Introduction
› How does composting work?
› Composting: process management
› Conclusions
www.fibl.org Introduction to composting and anaerobic digestion, Tartu, Nov. 2012, jf
Introduction ?
www.fibl.org Introduction to composting and anaerobic digestion, Tartu, Nov. 2012, jf
Introduction
› What means composting ?
The term „composting“ describes a natural process,
in which microorganisms transform organic residues
in stabilized products.
Products resulted from composting:
- “heat”
- compost (more or less mature)
www.fibl.org Introduction to composting and anaerobic digestion, Tartu, Nov. 2012, jf
Introduction
› Composting. Compost ?
Composting shall not only be a cheap waste
treatment. It shall be a way to improve soil fertility,
the plant growth and the plant health in long terms.
These improvements shall be approved by the
process control.
www.fibl.org Introduction to composting and anaerobic digestion, Tartu, Nov. 2012, jf
Introduction
› Compost ?
Compost is the solid, crumble, brownish to black
brown product of an aerobic degradation of biogenic
waste or organic material. There are huge numbers of
microorganisms working under constant access of
air (oxygen) and with enough moisture in the material
mix. There is not only degradation, but also new
formation.
Biology of composting 07.11.2012, Tartu (Estonia)
jf, FiBL, CH-Frick 2
www.fibl.org Introduction to composting and anaerobic digestion, Tartu, Nov. 2012, jf
Introduction
› What is suitable for composting ?
Green waste
www.fibl.org Introduction to composting and anaerobic digestion, Tartu, Nov. 2012, jf
Introduction
› What is suitable for composting ?
Egg shells
www.fibl.org Introduction to composting and anaerobic digestion, Tartu, Nov. 2012, jf
Introduction
› What is suitable for composting ?
manure
www.fibl.org Introduction to composting and anaerobic digestion, Tartu, Nov. 2012, jf
Introduction
› What is suitable for composting ?
› Theoretically all organic residues can be composted or digestated.
› However, not each one is easy to handle, biodegradable, and free from toxics and pathogenic germs.
› Depending of the system used, some residues are more or less easy to be treated
› Depending of the system, some input materials have to be treated before processing (e.g. pasteurization of kitchen waste before mesophilic anaerobic digestion)
› The start mixture is important for the success of the process
www.fibl.org Introduction to composting and anaerobic digestion, Tartu, Nov. 2012, jf
Introduction
› Ways of degradation for organic material:
Anaerobic(anaerobicdigestion)
Aerobic(composting)
www.fibl.org Introduction to composting and anaerobic digestion, Tartu, Nov. 2012, jf
Introduction
› Differences between
composting and anaerobic digestion?
› Oxygen
› Energy balance
› Degradation products
› Phases
› Utilization field
› Lignin (wood) can not be decomposed anaerobe!
Biology of composting 07.11.2012, Tartu (Estonia)
jf, FiBL, CH-Frick 3
www.fibl.org Introduction to composting and anaerobic digestion, Tartu, Nov. 2012, jf
How does composting work ?
www.fibl.org Introduction to composting and anaerobic digestion, Tartu, Nov. 2012, jf
How does composting work ?
› The natural cycle of life
Energie
CO2O2
Watermicroorganisms
Energy(heat)
Humus(compost)
Mineral nutrients
O2 CO2
livingorganisms
Organic residues
www.fibl.org Introduction to composting and anaerobic digestion, Tartu, Nov. 2012, jf
How does composting work ?
› Two elements are especially important in the cycle of life:
› Carbon (source of energy)
› Nitrogen (protein formation)
1 www.fibl.org Introduction to composting and anaerobic digestion, Tartu, Nov. 2012, jf
How does composting work ?
› The cycle of carbon:
www.fibl.org Introduction to composting and anaerobic digestion, Tartu, Nov. 2012, jf
How does composting work ?
› The cycle of nitrogen:
www.fibl.org Introduction to composting and anaerobic digestion, Tartu, Nov. 2012, jf
How does composting work ?
› The microorganisms of composting
Bacteria Mushrooms Actinomycetes
Biology of composting 07.11.2012, Tartu (Estonia)
jf, FiBL, CH-Frick 4
www.fibl.org Introduction to composting and anaerobic digestion, Tartu, Nov. 2012, jf
How does composting work ?
› The microorganisms of composting
› Bacteria
› aerobic / anaerobic
› very active at the beginning
of the process
› responsible for the hot phase
› can not abolish wood efficiently
www.fibl.org Introduction to composting and anaerobic digestion, Tartu, Nov. 2012, jf
How does composting work ?
› The microorganisms of composting
› Mushrooms
› aerobic
› abolish wood
› creation of stabilized crumbs
› important during maturity stage
www.fibl.org Introduction to composting and anaerobic digestion, Tartu, Nov. 2012, jf
How does composting work ?
› The microorganisms of composting
› Actinomycetes (ray fungus)
› can abolish substances, which can
not be abolish with bacteria or
mashrooms, for example chitin
› responsible for decomposition of difficult decomposable materials
www.fibl.org Introduction to composting and anaerobic digestion, Tartu, Nov. 2012, jf
How does composting work ?
› Composting: two steps system
› Step 1: Process of decomposition (mostly bacteria at work)
› intensive microbiological activity
› increasing in temperature
› extreme loss in volume
› naturally hygienisation
› Step 2: Maturity stage (mostly mushrooms at work)
› creation of stable humus
› development of positive characteristics of compost
www.fibl.org Introduction to composting and anaerobic digestion, Tartu, Nov. 2012, jf
How does composting work ?
› Degradation of cellulose during hot step
CO2 + H2O + energie
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www.fibl.org Introduction to composting and anaerobic digestion, Tartu, Nov. 2012, jf
How does composting work ?
› Degradation of proteins during hot step
NH3 + CO2 + H2O + (H2S) + energie
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Biology of composting 07.11.2012, Tartu (Estonia)
jf, FiBL, CH-Frick 5
www.fibl.org Introduction to composting and anaerobic digestion, Tartu, Nov. 2012, jf
How does composting work ?
› Dissolution of ammonia in water
liquid ammonia
&
+&
-
ammonia
ammonium
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www.fibl.org Introduction to composting and anaerobic digestion, Tartu, Nov. 2012, jf
How does composting work ?
› Nitrification to nitrate
nitric acid
oxygen
water Illu
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-
& -&+&
& & +&
ammonium
nitrate
liquid ammonia
www.fibl.org Introduction to composting and anaerobic digestion, Tartu, Nov. 2012, jf
How does composting work ?
› Maturity stage protein
(ammoniac) NH3
NH 4+ (ammonia) & OH -
(basic)
(oxygen from air) O2
NO 3-
(nitrate) & H+ (acide) & 22 H O (Wasser)
nitric acid
gaseouslosses
Nitrit NO 2-laughing gas N O2
air nitrogen N2
(water) 2OH
gaseouslosses
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www.fibl.org Introduction to composting and anaerobic digestion, Tartu, Nov. 2012, jf
How does composting work ?
› Maturity stage› Decomposition of lignin and building of humus
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www.fibl.org Introduction to composting and anaerobic digestion, Tartu, Nov. 2012, jf
How does composting work ?
› The process parameters
› Temperature
› Composition of gases
› Nmin forms
› Organic substance
› pH-value
› Intensity of extract coloration
www.fibl.org Introduction to composting and anaerobic digestion, Tartu, Nov. 2012, jf
How does composting work ?
› Evolution of temperature during composting
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Duration of process
10
30
50
70
Biology of composting 07.11.2012, Tartu (Estonia)
jf, FiBL, CH-Frick 6
www.fibl.org Introduction to composting and anaerobic digestion, Tartu, Nov. 2012, jf
How does composting work ?
› Evolution of gas composition during composting
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Duration of process0
10
20
O2
CO2
www.fibl.org Introduction to composting and anaerobic digestion, Tartu, Nov. 2012, jf
How does composting work ?
› Evolution of Nmin forms during composting
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Duration of process0
200
400
600
NO3--NNH4
+-N NO2--N
www.fibl.org Introduction to composting and anaerobic digestion, Tartu, Nov. 2012, jf
How does composting work ?
› Evolution of pH during composting
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Duration of process4
5
6
7
8
9
www.fibl.org Introduction to composting and anaerobic digestion, Tartu, Nov. 2012, jf
How does composting work ?
› Evolution of organic substance during composting
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Duration of process20
30
40
50
60
70
80
www.fibl.org Introduction to composting and anaerobic digestion, Tartu, Nov. 2012, jf
How does composting work ?
› Evolution of water extract coloration during composting
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Duration of process0
50
100
150
www.fibl.org Introduction to composting and anaerobic digestion, Tartu, Nov. 2012, jf
How does composting work ?
› Evolution of undesirable materials during the rotting process
› heavy metals
Biology of composting 07.11.2012, Tartu (Estonia)
jf, FiBL, CH-Frick 7
www.fibl.org Introduction to composting and anaerobic digestion, Tartu, Nov. 2012, jf
How does composting work ?
› Evolution of undesirable materials during the rotting process
before
for example90 kg
degradablematerial
for example10 kg non-degradable
material = 10 %
for example45 kg
degradablematerial
for example10 kg non-degradable
material= 18 %
after
www.fibl.org Introduction to composting and anaerobic digestion, Tartu, Nov. 2012, jf
How does composting work ?
› Evolution of undesirable materials during the rotting process
› heavy metals
› other chemical compounds ???
› pathogenic germs and weed seeds
www.fibl.org Introduction to composting and anaerobic digestion, Tartu, Nov. 2012, jf
How does composting work ?
› Final product: compost
› organic fertilization
› amelioration of soil structure
› biological plant protection product
› Compost is not waste material !
www.fibl.org Introduction to composting and anaerobic digestion, Tartu, Nov. 2012, jf
Composting: process management
www.fibl.org Introduction to composting and anaerobic digestion, Tartu, Nov. 2012, jf
Composting: process management
› Process management:
From collecting of green waste
to utilization of the final product
www.fibl.org Introduction to composting and anaerobic digestion, Tartu, Nov. 2012, jf
Composting: process management
› Factors of process management:
› Concept of green manure collection
› Composting system
› Mixture of raw materials
› Process management
› Storage of end-material
Biology of composting 07.11.2012, Tartu (Estonia)
jf, FiBL, CH-Frick 8
www.fibl.org Introduction to composting and anaerobic digestion, Tartu, Nov. 2012, jf
Composting: process management
› Concept of waste collection
www.fibl.org Introduction to composting and anaerobic digestion, Tartu, Nov. 2012, jf
Composting: process management
› Concept of green manure collection
› Can influence the quality of input materials (e.g. quantity of undesirable inputs)
› Organizing the materials needed to become an adequate start mixture
www.fibl.org Introduction to composting and anaerobic digestion, Tartu, Nov. 2012, jf
Compost quality management
› Composting system
www.fibl.org Introduction to composting and anaerobic digestion, Tartu, Nov. 2012, jf
Composting: process management
› Composting system
› Each composting system, has its own specificities
› The different management operation have to be adapted to the system
› Mixture composition
› Coarseness of the start mixture
› Aeration and humidity management
› …
www.fibl.org Introduction to composting and anaerobic digestion, Tartu, Nov. 2012, jf
Compost quality management
› Composition of the start mixture
www.fibl.org Introduction to composting and anaerobic digestion, Tartu, Nov. 2012, jf
Composting: process management
› Start mixture
› C:N-ratio („available“)
Biology of composting 07.11.2012, Tartu (Estonia)
jf, FiBL, CH-Frick 9
www.fibl.org Introduction to composting and anaerobic digestion, Tartu, Nov. 2012, jf
Composting: process management
› C:N-ratio of some materials› Urine: 0.8
› Feathers: 4 – 5
› Chicken manure: 8 – 10
› Grass: 12
› Mature compost: 12 – 15
› Young compost: 15 - 18
› Cows manure: 15 – 20
› Kitchen waste: 23
› Ideal C:N of start mixture: 30 – 35
› Trees leaves 50
› Straw 50 – 150
› Wood (sawdust): 200 - 500
www.fibl.org Introduction to composting and anaerobic digestion, Tartu, Nov. 2012, jf
Composting: process management
› Start mixture
› C:N-ratio („available“)
› Structure, moisture
› “Ideal mixture”:
› 1/3 rough wood (shredded wood, sieved rest material from compost, snipped bark)
› 1/3 medium-fine, fibrous material(shredded branches, wood fibers, straw, foliage, switch grass , reed, peat from consumed potting compost)
› 1/3 material, nearly without structure(dung, grass, rumen contents, vegetables manure)
› Evtl. utilization of additivespowdered clay, earth, enzymes, microorganisms, fertilizer, etc.
www.fibl.org Introduction to composting and anaerobic digestion, Tartu, Nov. 2012, jf
Compost quality management
› Process management: humidity
www.fibl.org Introduction to composting and anaerobic digestion, Tartu, Nov. 2012, jf
Composting: process management
› Process management: humidity
› Enough humidity is necessary to allowed microorganism activities
› Too much humidity prevent a good aeration of the composting material and so a good process development
› At the begin of the process, an important quantity of water is need
› During the maturity phase, the addition of water is to performed very carefully
› Humidity management is one of the most difficult role of the compost manager !
www.fibl.org Introduction to composting and anaerobic digestion, Tartu, Nov. 2012, jf
Compost quality management
› Process management: aeration
www.fibl.org Introduction to composting and anaerobic digestion, Tartu, Nov. 2012, jf
Composting: process management
› Process management: aeration
› Mushrooms need oxygen to be active.
› Bacteria can be active without free oxygen. But then they take oxygen from other molecules, what can cause the production of toxic compounds (e.g. nitrite from nitrate)
› The aeration of the compost during the maturation phase is very important. The quality of the products depreciated if not enough oxygen is then available.
Biology of composting 07.11.2012, Tartu (Estonia)
jf, FiBL, CH-Frick 10
www.fibl.org Introduction to composting and anaerobic digestion, Tartu, Nov. 2012, jf
Compost quality management
› Process management: compost turning
www.fibl.org Introduction to composting and anaerobic digestion, Tartu, Nov. 2012, jf
Composting: process management
› Process management: compost turning
› Compost turning is not only important to assure an sufficient oxygenation of the compost during the process
› Compost turning is important to become an homogenous product
› Compost turning activate also activate the biological activity of the process
www.fibl.org Introduction to composting and anaerobic digestion, Tartu, Nov. 2012, jf
Compost quality management
› Process management: storage of the products
www.fibl.org Introduction to composting and anaerobic digestion, Tartu, Nov. 2012, jf
Composting: process management
› Process management: storage of the products
› Compost is an living product. If he didn’t be come oxygen, he will died !
› Mature compost didn’t need a lot of oxygen. But a minimum has to be assure. Different factors are important:› Dimensions of the storage pile
› Maturity stage of the products
› Humidity
› Use of additives
› …
www.fibl.org Introduction to composting and anaerobic digestion, Tartu, Nov. 2012, jf
Compost quality management
› Process management: storage of the products
www.fibl.org Introduction to composting and anaerobic digestion, Tartu, Nov. 2012, jf
Conclusions
Biology of composting 07.11.2012, Tartu (Estonia)
jf, FiBL, CH-Frick 11
www.fibl.org Introduction to composting and anaerobic digestion, Tartu, Nov. 2012, jf
Conclusions
› Knowledge of the biology of composting is essential to understand and managed the process
› Process management is the key for a successful production quality compost
› Compost quality is the basic condition to improve the market for the products and so to secure the system.
www.fibl.org Introduction to composting and anaerobic digestion, Tartu, Nov. 2012, jf
Thank you very much for your attention …
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