__Basics of composting and composting technologies - Tunesia 2025 sm (1)

Composting Basics and Technologies

Composting Content

• Composting Definition: Controlled aerobic biological decomposition of organic matter into humus-like compost.

• Reasons for Composting.

• Essential Controlling Parameters.

• Raw Material Pre-treatment.

• Composting Systems.

• Environmental Concerns.

• Quality Criteria.

• Conclusion.

Organic Waste Sources

• Household residual waste.

• Separately collected household biowaste: food and kitchen waste.

• Household green waste.

• Green waste from cities and industry.

• Organic wastes from agriculture: plant residues, animal manure, wood.

• Separately collected biowaste from restaurants, canteens, and food industry.

• Sewage sludge from municipal wastewater treatment plants.

• Organic waste from industry: paper waste, sewage sludge.

• Dead animals, animal waste, meat processor waste, and fishing industry waste.

Biological Treatment Concepts for Biogenic Waste Streams

• Separately collected biogenic waste can be treated through:

  • Anaerobic digestion: Used for food waste, biowaste, and green waste to produce biogas and digestate.

  • Composting: Used for biowaste and green waste to produce compost.

• Mixed collected waste undergoes MBT (Mechanical Biological Treatment) for energy and material recovery.

  • This process yields high calorific fraction/RDF (Refuse-Derived Fuel), recyclables, inert organic, and mineral fractions.

Management of Biodegradable Waste

• Biowaste is a source of organic fertilizer (humus and nutrients).

• It can be used as raw material for biogas production, combined with organic fertilizer production (power, heat, and compost).

• The use of biowaste offers opportunities for $CO_2$ reduction.

• Separate biowaste recycling reduces landfill space consumption.

Composition of Household Waste in Germany

• Data in weight percent:

  • Organic waste: 39.3%

  • Paper, cardboard: 8.9%

  • Plastic: 6.7%

  • Waste paper: 6.3%

  • Old textiles: 5.2%

  • Fine waste (0-10 mm): 4.6%

  • Other refuse: 4.3%

  • Glass for recycling: 3.9%

  • Harmful substance: 3.5%

  • Composite material: 2.0%

  • Metal: 1.3%

  • Native-organic waste: 0.5%

  • Synthetic material: 13.5%

  • Inert material: 0.5%

  • Wood/Cork: 0.5%

  • Hygiene product: 0.5%

• Per Inhabitant:

  • 59 kg/(I*a) in bio-bin collected.

  • 66 kg/(I*a) green waste.

• Collection of native kitchen organic matter (food and kitchen waste) is completely unsatisfactory, potential is far from being completely utilized. Food and kitchen waste often found more in the residual waste bin than in the organic waste bin.

Use of Organic Wastes

• Organic wastes can be used for:

  • Animal feed

  • Direct landfilling

  • Land spreading

  • Anaerobic digestion

  • Disposal in kitchen sink

  • Incineration

  • Backyard composting

  • Composting

  • Mechanical-biological treatment

Direct Landfilling

• Main method worldwide.

• Harms the local environment (leachate, dust, odor, vermin problems).

• Has negative effects on the environment in general:

  • Landfill gas (GHG).

• In Germany: forbidden.

One Reason for Composting

• Climate protection.

• No landfilling of organic wastes.

Landfilling

• Landfilling of untreated waste harms the local and global environment.

• Earth's climate is damaged by escaping landfill gas (methane - at least 28 times more potent in trapping heat than carbon dioxide).

• Reduce climate gas emission from landfills by utilizing all organic wastes (composting, fermentation).

What Happens in a Landfill?

• Anaerobic degradation of organic materials.

• Biogas (landfill gas):

  • Mainly $CH<em>4$ (methane) and $CO</em>2$ (carbon dioxide).

  • Includes a lot of trace gases.

• Organic and toxic leachate.

• Low load-bearing capacity.

• Intensive settling (especially uneven settling).

Landfill Carbon Mass

• Carbon inputs: Degradable and non-degradable materials.

• Carbon storage: Lignin, biomass, undecomposed cellulose and hemicellulose, etc.

• Outputs: VOCs, $CH<em>4$, $CO</em>2$.

Estimated Global Anthropogenic Methane Emissions by Source

• Source: GLOBAL ANTHROPOGENIC EMISSIONS OF NON-CO2 GREENHOUSE GASES, 1990-2020 (EPA REPORT 430-R-06-003).

Avoidance of $CO_2$ Emissions

• Comparing different waste disposal technologies.

Emissions of $CO_2$-Equivalents from Landfills

• Content of biologically degradable material for landfilling (BMW).

What is Composting?

• Composting is the controlled aerobic biological decomposition of organic matter into a stable, humus-like product called compost.

• It is essentially the same process as natural decomposition except that it is enhanced and accelerated:

  • By mixing organic waste with other ingredients to optimize microbial growth.

  • By controlling and creating optimal conditions for the micro-organisms (aeration, regulation of the water balance).

Composting

• Aerobic decomposition of organic materials in a thermophilic temperature range.

• High temperatures are necessary to kill weed seeds and organisms that cause disease in humans, plants, and animals (sanitized compost).

• Agricultural and horticultural use is a good way of reclaiming nutrients from organic refuse to improve the condition of soils.

• A good and usable compost can only be produced out of separately collected organic wastes!

Composting - Aerobic Respiration

• Aerobic micro-organisms use molecular oxygen ($O_2$) to liberate the bulk of the energy from the carbon source.

• $[C,O, 4H] + O<em>2 \rightarrow CO</em>2 + 2H_2O + Energy (Temperature)$

• AEROB DECOMPOSITION: $C<em>6H</em>{12}O<em>6 + 6 O</em>2 \rightarrow 6 CO<em>2 + 6 H</em>2O$ Energy = – 2.875 kJ/Mol HEAT!

Close the Natural Circle of Life

• To compost materials means also to close the natural circle of life.

• Reduce the use of mineral fertilizer.

• Compost as a source to provide:

  • Nutrients for the plants.

  • To adjust the soil conditions.

  • Humus (organic matter) source.

Reasons for Composting

• 40% or much more of produced waste (MSW) is from organic origin.

• Organic components in landfill cause higher gas (mainly methane) and leachate production and instability of waste body.

• Composting is a sustainable method to use biological resources with a useful and environmental aim.

Composting - Basics of Composting

• Composting is a Microbial Process.

Composting Microbes

• Bacteria

• Fungi

• Protozoa

• Actinomyces

Primary Needs of Composting Microbes

• Carbon - for carbohydrates for energy.

• Nitrogen - for nutrients and proteins to build biomass.

• Some other nutrients (P …).

• Oxygen - for aerobic respiration.

• Moisture - necessary for biological functions.

• pH – an initial range of 5 to 8 is preferable.

Recommended Conditions for Rapid Composting

The Composting Process

• (Leslie Cooperband; University of Wisconsin-Madison; 2002)

Stages of Composting Operation

• Stages of Composting Operation.

Proper C:N Ratio

• Necessary to optimize composting conditions

• C:N = 30:1 to 40:1 is optimum for composting

• If C:N < 20:1, odors occur and nutrients may be lost

• If C:N > 40:1, composting process slows down

Carbon : Nitrogen ratio (C:N) of compost materials

• Dairy manure 20:1

• Sheep manure 14:1

• Poultry manure 10:1

• Humus 10:1

• Vegetable wastes 12:1

• Seaweed 19:1

• Straw 80:1

• Corn stalks 60:1

• Leaves 45:1

• Alfalfa 13:1

• Legume/grass hay 25:1

• Grass hay; garden waste 80:1

• Rotted sawdust 200:1

• Fresh sawdust; wood 500:1

• Paper 170 - 800:1

Question

• The compost organisms work best at a C/N of 25:1 - 35:1

• How can this C/N ratio be achieved?

C/N Ratio Change Over Time

• C/N Ratio change over the composting time.

Important Parameters During Composting Process

• Air (oxygen)

Parameters of the Composting Process

• Oxygen Level:

  • At process start: minimum 3 - 4 %

  • Provide a good structure in the pile to ensure a homogeneous repartition of the oxygen (avoid lumps formation).

  • Poor rotting leads to fermentation processes (anaerobic digestion).

  • Odor (hydrogen sulfide ($H<em>2S$), ammonia ($NH</em>3$)).

  • Development of gases harmful to the climate (methane ($CH<em>4$) and nitrous oxide ($N</em>2O$)).

Important parameters during the composting process

• Carbon dioxide / Oxygen

• Degradation and maturation phase

• Degradation phase has high oxygen demand!!

• Active microbes need $O<em>2$ and produce $CO</em>2$

• > 3 to 5 % $O_2$ in the compost pile

Changes in $CO<em>2$ & $O</em>2$ Concentration without Aeration

• Changes in $CO<em>2$ & $O</em>2$ concentration without aeration.

Important Parameters During Composting Process

• Moisture:

  • Aerobic bacteria need moisture to decompose organics

Proper Moisture and Air in Composting Material

• A compost pile needs water because the organisms grow in a moist environment - micro-organisms need water to survive.

• However, too much water and organisms drown without oxygen.

• 40 % - 50 % moisture content (MC) is optimum to provide organisms with both air and water (depends on material).

Structure - Proper Particle Size

• Porosity affects aeration.

Average Moisture Content during Compost Process

• Average Moisture Content during Compost Process.

Mix Well; Do Not Compact

• Mix carbon & nitrogen materials together to provide a balanced diet.

• Add water if the mixture is too dry; or add more dry materials if the mixture is too wet.

• Do not compress/compact the mixture; keep space for air to flow in the compost Pile.

Question

• Why was water added?

• How do you control the water content in the compost heap?

• How do you increase the water content?

Process Factor - Temperature

• Active aerobic organisms are the reason for the production of thermal energy.

• The temperature influences the degeneration process mainly the speed of degeneration because the general rule is that the activity of micro-organisms rises with an upgrowing temperature.

• Hygienisation

Temperature Changes in a Compost Pile

• Important to monitor; very easy to measure; shows the success of composting.

Results of Evaluation - Temperature Profiles

• Temperature profiles during composting.

Lag Phase - Bacterial Growth Curve

• Lag phase - time required for the organisms to acclimate to the new environment

• No increase in the number of viable cells (period of active growth without cell division and cells for preparation)

Process Factors - Aeration

• Supply with oxygen to keep the micro-organisms alive (aerobe decomposition).

• Taking away the carbon dioxide.

• Reduction of water content (dry the material!).

Changes in $CO<em>2$ & $O</em>2$ Concentration without Aeration

• Changes in $CO<em>2$ & $O</em>2$ concentration without aeration.

Process Factor - Temperature

• Why does a well-working compost heap get warm?

• How do you control the temperature in the windrow and how often?

• What is the relevance of the temperature in the windrow for the compost product?

Process Factor - pH – Level

• The activity of the micro-organisms is closely related to the pH – Level of the input substrate.

• pH influence availability of nutrients.

• Good for biological activity are pH - Levels between 5.5 and 8.

• Too low-pH conditions are a frequent process problem in food waste composting!

Monitor the Compost Process

• Temperature – the primary way to determine if the micro-organisms are healthy.

• Moisture & air – easily assessed by inspecting the quality of the compost pile.

• Smell – odor is a key indicator of whether composting is progressing properly.

The Composting Process

• (Leslie Cooperband; University of Wisconsin-Madison; 2002)

Two Types of Materials Are Needed

• Dry Organic Materials:

  • Are high in carbon & low nitrogen.

  • Tend to be dry.

  • Have the structure to allow aeration.

  • Carbon is the primary food for composting organisms.

  • Includes such materials as wood chips, brush, and tree trimmings.

• Wet Organic Materials:

  • Are high in nitrogen & low in carbon.

  • Have a high moisture content.

  • Nitrogen is the primary building block for composting organisms.

  • Includes such materials as grass, fruits, vegetables.

Unsuitable Input Materials

• Recyclable materials.

• Harmful substances.

Totally Unsuitable Materials for Composting

• Totally Unsuitable Materials for Composting.

Suitable Input Materials

• Organic Kitchen Waste.

• Organic Garden Waste + Agricultural Waste.

Composition of the Input Material

• Easiest composition by volume is to mix wastes without structure (mostly with narrow C/N-ratio) with structure material (wide C/N-ratio).

• Because the biowaste characteristics are quite different, it is not possible to give exact numbers about a suitable composition of the input materials.

Proper Particle Size

• Breaking large pieces of materials into small pieces will increase the surface area where micro-organisms can live and feed.

• This speeds up composting.

• Not too big and not too small - a mixture of 1 – 10 cm size materials is ideal.

• Pieces that are too small will not allow fresh air to flow through it.

Structure - Proper Particle Size

• Porosity affects aeration.

Putting the Fundamentals into Practice

• A correctly built and managed composting pile will:

  • Reach high temperatures.

  • Destroy weed seeds.

  • Control pathogens.

  • Avoid odor problems.

  • Produce finished compost in 2 – 3 months.

Operation Quality and Product Quality

• Hygienic harmlessness.

What is Sanitising (Hygienisation, Pasteurisation)?

• Sanitizing treatment shall mean: biotechnological treatment of biodegradable materials for sanitation purposes

  • pasteurization

  • aerobic sanitizing treatment (thermophilic composting)

  • anaerobic sanitizing treatment (thermophilic anaerobic digestion)

  • any other form of sanitizing treatment

Putting the Fundamentals into Practice

• Managing the composting operation to optimize conditions requires many things:

  • Site selection and design

  • Composting methods

  • Equipment and staffing

  • Operational controls

  • Monitoring & recordkeeping

  • Site maintenance

  • But first, regulatory compliance

Repetition and Application - Compost Technology

• Repetition and Application - Compost Technology.

The Composting Process

1. Collection

2. Sorting

3. In-Vessel Composting

4. Open Windrow Composting for Green waste

5. Screening and Grading

6. Compost

Systematic Waste Separation

• Systematic waste separation.

Separate Collection Germany – Rural Area

• Collection systems.

Separate Collection in Germany - Collection Systems

• Curbside System

  • systematic collection

    • container/sack systems and equipment, vehicles specially designed for container systems

  • unsystematic collection

    • special containers and/or vehicles

• Bring Systems

  • depot containers

  • occasionally depots present for green waste

Principal Set-Up of a Composting Facility

• WASTE + Additives + Air -> COMPOST + Residues

• Delivery, Storage -> Pre-treatment -> Mixing -> Rotting -> Post-treatment -> Residues

• Process-Exhaust Air -> Air Treatment

• Process water -> Water Treatment

Bio-Waste Collection

• Automated side loader.

• Rotary drum vehicle.

• Rear-loader waste collection vehicle.

Green Waste - Garden Waste and Kitchen Waste - Bio Waste

• Green Waste - Garden Waste and Kitchen Waste - Bio Waste.

Transportation - Bio Waste Storage (Kitchen Waste)

• Transportation - Bio Waste Storage (Kitchen Waste).

Garden and Green Waste Storage

• Garden and Green Waste Storage.

Shredding of Green Waste

• Shredding of Green Waste.

Drum Screens

• Drum Screens.

Screening, Mixing, and Sorting Out of Impurities (Metals)

• Screening, mixing, and sorting out of impurities (metals).

Manual Sorting Out of Impurities

• Manual sorting out of impurities.

Compost Technology - Composting Methods

• Composting Methods:

  • Closed:

    • Static:

      • Tunnel

      • Container

    • Dynamic:

      • Tunnel

    • Quasi dynamically:

      • Floor reactors

      • Tunnel

    • Encapsulated:

      • Static or Dynamic.

  • Open:

    • Windrow composting

    • Aerated Static Pile Composting

    • Aerated Turned Pile Composting

    • Brikollare-methode

    • Tower

    • Container

Thermophilic Phase

• Most intensive phase of rotting

• decomposition phase

• thermophilic bacteria

• Sanitation temperature

• Sanitation time window

• High Oxygen demand – Aeration!

• High production of emissions - Encapsulation!

• High water demand

• In-Vessel Composting

• Exhausted Air treatment

Composting Systems - Open

• Windrow

  • Triangular or trapezoidal shaped row of solid waste.

  • Periodically turned by front-end loader or turner.

  • Incorporate systems have perforated ducts beneath the long rows for controlled aeration.

  • Disadvantages are: large land area requirements, high odor potential.

Open Windrow System

• Open windrow system – like backyard composting windrow is normally not covered (plastic foil; membrane textiles).

  1. Chop/Shred waste

  2. Mix different types of waste thoroughly and spread hand-high hoe, shears, shredder

  3. Spread additives (as required)

  4. Moisten if necessary

  5. Add further layers of waste in the same way

  6. Finished compost heap

Windrow Composting

• Windrows of yard debris, manure, and food waste at a composting site.

• Combination of the natural aeration and the turning of the windrows

Simple Green Waste Composting

• Simple Green Waste Composting.

Temperature Profile in the Compost Windrow

• Turning is important!

Turned Windrow - Composting Systems

• Turned Windrow - Composting Systems.

Tractor-Pulled Compost Turning Machine - Sideturn

• Tractor-Pulled Compost Turning Machine - Sideturn.

Tractor-Pulled Compost Turning Machine

• Tractor-Pulled Compost Turning Machine.

Self-Propelled Compost Turning Machines

• Self-Propelled Compost Turning Machines.

Mechanical and Passive Ventilation

• Turning of compost mix the rotting material (and also aerate).

• Passive ventilation with pipes; active ventilation with pipes.

Aeration Passively Aerated Windrow System

• Aeration Passively Aerated Windrow System.

• HIGH-TEMPERATURE COMPOST HEAP (USING Bamboo for AERATION).

Composting Systems – Active Aerated

• Static Pile

  • Low technology method of open-air stock piling of solid waste

  • Aeration is provided by occasional turning or aeration ducts

  • Disadvantages are: long retention times, higher odor potential, large land area requirements

Composting Systems - Active Aerated

• Composting Systems - Active Aerated.

Extended Pile with Floor Aeration Compost System

• Extended Pile with Floor Aeration Compost System.

Indoor Composting Systems – Active Aerated and Turned

• Extended Pile.

• A Buhler windrower turning compost in an extended pile with floor aeration system.

Active Aerated - Oxygen-Optimised Composting

• Umweltelektronik compost control system

• Active Aerated - Oxygen-Optimised Composting.

Rotting Phases - A Technical Point of View

• heap temperature in °C

• Rotting Phases - A Technical Point of View

In-Door-Composting? - Membrane Textile Cover

• rainy winter conditions and hot, dry summers

• to maintain optimum moisture and avoid leaching

• reducing odor emissions

Cover Membrane

• membrane laminate technology similar to that of its world-famous GORE-TEX®

• weather

• uv-resistant face layer

• air, moisture impact management: GORE™ Cover

• ePTFE Membrane

• back layer

• odor, dust, germs, and bacteria

Covered Aerated Static Pile Composting

• Winding Machine

• GORE Cover

• Anchor System

• THE GORE COVER SYSTEM - 3D VIEW

• Moisture

• Individual Blower Unit

• Oxygen Sensor

• Control Unit

• Temperature Sensor

• PC

Covered Aerated Static Pile Composting

• a trend from open windrow towards in-vessel system, containment, and process control

• economic and technically acceptable alternative to in-vessel systems

• achieve same aims

Composting Systems - Indoor Systems

• In-Vessel-Composting

  • composting within an enclosed structure or vessel

  • Biomass may be mixed, transported, and aerated by mechanical means and programmed automatically

  • Vessels are: large circular tanks, vertical silos, containers, boxes, or tunnel reactors

  • Disadvantages are: high cost of construction and operation

  • Advantages are: shorter retention time, (5 – 10 days), less land requirements, excellent process control, high quality and consistent end – product, good odor control

  • Temperature control (sanitation)

Tunnel, Container, and Box Composting Systems

• Tunnel composting system

• Container composting system

• Box composting system

  • Areation

  • Cleaning of exhaust air (Biofilter)

  • Water management (Irrigation; Drainage; water surplus, water demand)

  • waste input

  • compost output

  • process water

  • exhaust air

  • air recirculation

  • fresh air

  • inlet air

Turned Bed Composting System - Line Composting System (Tunnel Composting)

• Composting between walls which form long, narrow channels

• Aeration

• Compost-turning machine

  • exhaust air

  • circulating air

  • supply air

Drum Composting System

• In-vessel composting

  • Die Abluft aus den Trommeln wird über ein Biofilter gereinigt.

Typical Emissions from Biological Treatment Facilities

• Air: Micro-organisms, Dust, Odour, VOCs, Bio-aerosols

• Controlled Waters: Untreated waste water – abatement through bunding, drainage collection and hard standing should be in place

• Land: Litter

Emissions from Biological Treatment Facilities

• Compost:

  • Air: Micro-organisms, Dust, Odour, VOCs, Oxides of nitrogen, Bioaerosols.

  • Controlled Waters: Untreated waste water-abatement through bunding, drainage collection and hard standing should be in place

  • Land: Litter.

• Anaerobic Digestion:

  • Air: Odours, VOCs, Methane(hydrogen sulphide), Carbon dioxide.

  • Controlled Waters: Untreated waste water-abatement

  • Land: Litter.

• Mechanical Biological Treatment:

  • Air: Micro-organisms, Dust, Odour

  • Controlled Waters: Untreated waste water-abatement

  • Land: Litter.

Biological Waste Gas Treatment - Biofilter

• odorous emissions from the composting process

• biofilter - composting reactor

• treatment of airstream containing high concentration of $H_2S$, ammonia, VOC or a combination of all three

• biofilter media (matured screened compost from green and yard waste)

Biofilter

• Biofiltration is a process for reducing the polluting substances in the air which uses biological “oxidation” - degradation

• contaminated air is lead through a substrate which contains microorganisms capable of decomposing the polluting substances using them as a nutrition source

• biologically oxidation of volatile organics

• economically more advantageous than the combustion systems

• Effective only for biodegradable compounds

• No filter!! Aerobic Bio-reactor

Biofilter Illustration

• INPUT PIPE FOR THE AIR

• FILTERING BED TO BE DEPURATED

• AIR DISTRIBUTION CHANNEL

• LEAN CONCRETE

• LEACHATE OUTLET

Biofilter Components

• Bio-filtration media

  • Wood chip

  • Compost

  • Peat

Biofilter - Odour-Treatment

• Biofilter - Odour-Treatment

Compost Marketing

• Compost Marketing.

Compost Marketing products

• Compost < 20 mm

• Compost > 20 mm

Compost Quality Characteristics

• Compost quality characteristics.

Repetition and Supplement

• How to get good composting?

• How to check the quality of the compost and monitor the rotting process?

Evaluation of the Quality with Own Senses

• Odor. The Compost Is Too Dry Right Moisture Content 40 – 60 % Too Wet Fist Test.

Average Moisture Content during Compost Process

• Average Moisture Content during Compost Process.

Important Parameters During the Composting Process

• Temperature

• Degradation phase

• With heat development

• Very important for the killing of pathogens and weed seeds in the compost

Temperature Profile in the Compost Windrow

• Turning process.

Recommended Conditions for Rapid Composting

The Composting Process

• Raw Materials: Organic matter, minerals, water, microbes -> Finished compost

Quality Control During Process and Product Control

• Quality Control During Process and Product Control.

Compost (Waste) Sampling

• Compost may be inhomogeneous

• Representative sampling is very important

• Variants of sampling to get a representative sample

  • Very large sample mass - crushed / quartered several times - laboratory sample

  • Small samples - Combine into a composite sample / quartered several times - laboratory sample

• A representative sample is defined as a small quantity or a subset of something larger. It represents the same properties and proportions as those of a larger mass of compost (waste).

Compost (Waste) Sampling Process

• Methods Book for the Analysis of Compost (2002)

Sampling from Heaps (PN 98)

• Number of individual samples per mixed sample depends on the volume of the heap

• Smaller heaps (Ø < 5m) at least 3 prospecting slots

Sampling from Heaps (PN 98)

• Piles / Heaps (Ø > 5m)

  • Distribute the slots in a grid pattern over the pile, take a composite sample from each slot

  • Take a mixed sample from each slot

Sampling of a Representative Sample of Compost from Heaps

• Procedure: Windrow composting

  • Make a cross-section with the auger up to the center of the windrow / heap basis according German compost methods of analysis

  • Boreholes are to be drilled over the entire heap

  • The samples are summarized, mixed, and split/ quartered single (individual) samples

Sizes and Numbers of Individual (Single) Samples

• Methods Book for the Analysis of Compost (2002)

Quartering the Collective Sample

• All individual samples -> Mixed Laboratory Sample

Sample Handling

• all tools, sampling devices and sample packaging must be clean and dry

• samples may only be placed in clean, dry and airtight packaging (bags, cans…)

• samples must be stored cold and analysed as soon as possible

• samples must be labelled waterproof and clearly legible

• samples must always be identifiable (what was sampled, when and where…)

Compost (Waste) Sampling Process

• Methods Book for the Analysis of Compost (2002)

The Nitrogen Cycle in Composting

• $N_{min}$ (Nmineralised )

  • Ammonium ($NH_4$-N)

  • Nitrite ($NO_2$-N)

  • Nitrate ($NO_3$-N)

Nitrogen Development in Compost

• Nitrogen in raw material:

  • Anaerobic conditions.

• Ammonium ($NH_4$-N) in Composting.

Available Nitrogen

• Mineralised forms of nitrogen in the composting process.

• nitrification takes place during the maturation phase

Interpretation of the Signification of the Quantity of the Different Forms of Mineralised Nitrogen Forms in Compost

• - none (<

Composting Basics and Technologies

Composting Content

• Composting Definition: Controlled aerobic biological decomposition of organic matter into a stable, humus-like compost, improving soil health and providing nutrients for plant growth. This process requires careful management of environmental conditions to optimize microbial activity.

• Reasons for Composting: Reduction of landfill waste, production of valuable soil amendment, and mitigation of greenhouse gas emissions. Composting also helps in nutrient recycling and improves soil structure.

• Essential Controlling Parameters: Carbon-to-Nitrogen ratio (C:N), moisture content, temperature, pH, oxygen levels, and porosity. Optimal ranges are crucial for efficient decomposition.

• Raw Material Pre-treatment: Shredding, mixing, and removal of unsuitable materials to enhance decomposition rates and ensure compost quality.

• Composting Systems: Open windrow, aerated static pile, in-vessel composting, and anaerobic digestion. Each system varies in complexity, cost, and efficiency.

• Environmental Concerns: Odor control, leachate management, and prevention of pathogen spread. Proper management practices are essential to minimize environmental impact.

• Quality Criteria: Nutrient content, stability, maturity, absence of contaminants, and particle size. Meeting quality standards ensures compost is safe and effective for its intended use.

• Conclusion: Composting is a sustainable waste management practice that converts organic waste into a valuable resource, offering numerous environmental and economic benefits.

Organic Waste Sources

• Household residual waste: Mixed waste containing food scraps, paper, and other organic materials.

• Separately collected household biowaste: food and kitchen waste, collected separately for composting or anaerobic digestion.

• Household green waste: Yard trimmings, leaves, and grass clippings.

• Green waste from cities and industry: Organic waste from parks, gardens, and landscaping operations.

• Organic wastes from agriculture: plant residues, animal manure, wood.

• Separately collected biowaste from restaurants, canteens, and food industry: Food scraps and organic waste from commercial food service establishments.

• Sewage sludge from municipal wastewater treatment plants: Solid waste from wastewater treatment processes.

• Organic waste from industry: paper waste, sewage sludge.

• Dead animals, animal waste, meat processor waste, and fishing industry waste: By-products from animal processing and fisheries.

Biological Treatment Concepts for Biogenic Waste Streams

• Separately collected biogenic waste can be treated through:

  • Anaerobic digestion: Used for food waste, biowaste, and green waste to produce biogas (methane) and digestate (nutrient-rich residue). This process occurs in the absence of oxygen.

  • Composting: Used for biowaste and green waste to produce compost, a stable humus-like material. This process requires oxygen and controlled conditions.

• Mixed collected waste undergoes MBT (Mechanical Biological Treatment) for energy and material recovery. This process yields high calorific fraction/RDF (Refuse-Derived Fuel), recyclables, inert organic, and mineral fractions.

Management of Biodegradable Waste

• Biowaste is a source of organic fertilizer (humus and nutrients): Provides essential elements for plant growth and improves soil structure.

• It can be used as raw material for biogas production, combined with organic fertilizer production (power, heat, and compost): Anaerobic digestion converts biowaste into biogas, a renewable energy source, and digestate, which can be used as fertilizer.

• The use of biowaste offers opportunities for $CO_2$ reduction: Diverting biowaste from landfills reduces methane emissions, a potent greenhouse gas.

• Separate biowaste recycling reduces landfill space consumption: Extends the lifespan of landfills and reduces the environmental impact of waste disposal.

Composition of Household Waste in Germany

• Data in weight percent:

  • Organic waste: 39.3%

  • Paper, cardboard: 8.9%

  • Plastic: 6.7%

  • Waste paper: 6.3%

  • Old textiles: 5.2%

  • Fine waste (0-10 mm): 4.6%

  • Other refuse: 4.3%

  • Glass for recycling: 3.9%

  • Harmful substance: 3.5%

  • Composite material: 2.0%

  • Metal: 1.3%

  • Native-organic waste: 0.5%

  • Synthetic material: 13.5%

  • Inert material: 0.5%

  • Wood/Cork: 0.5%

  • Hygiene product: 0.5%

• Per Inhabitant:

  • 59 kg/(I*a) in bio-bin collected

  • 66 kg/(I*a) green waste

• Collection of native kitchen organic matter (food and kitchen waste) is completely unsatisfactory, potential is far from being completely utilized. Food and kitchen waste often found more in the residual waste bin than in the organic waste bin.

Use of Organic Wastes

• Organic wastes can be used for:

  • Animal feed: Some organic wastes can be processed and used as animal feed.

  • Direct landfilling: The most common method globally, but environmentally problematic.

  • Land spreading: Application of organic waste to agricultural land as fertilizer.

  • Anaerobic digestion: Conversion of organic waste into biogas and digestate.

  • Disposal in kitchen sink: Grinding food waste and flushing it into the sewer system.

  • Incineration: Burning organic waste to reduce volume and generate energy.

  • Backyard composting: Small-scale composting at home.

  • Composting: Controlled aerobic decomposition of organic waste.

  • Mechanical-biological treatment: Combination of mechanical and biological processes to treat mixed waste.

Direct Landfilling

• Main method worldwide.

• Harms the local environment (leachate, dust, odor, vermin problems): Leachate can contaminate groundwater, and landfill gas contributes to air pollution.

• Has negative effects on the environment in general:

  • Landfill gas (GHG): Methane emissions contribute to climate change.

• In Germany: forbidden.

One Reason for Composting

• Climate protection: Reduces methane emissions from landfills.

• No landfilling of organic wastes: Diverts organic waste from landfills, promoting resource recovery.

Landfilling

• Landfilling of untreated waste harms the local and global environment: Untreated waste decomposes anaerobically, producing harmful greenhouse gases and leachate.

• Earth's climate is damaged by escaping landfill gas (methane - at least 28 times more potent in trapping heat than carbon dioxide): Methane emissions contribute significantly to global warming.

• Reduce climate gas emission from landfills by utilizing all organic wastes (composting, fermentation): Proper waste management practices can significantly reduce greenhouse gas emissions.

What Happens in a Landfill?

• Anaerobic degradation of organic materials: Decomposition occurs in the absence of oxygen, producing methane and other gases.

• Biogas (landfill gas):

  • Mainly $CH<em>4$ (methane) and $CO</em>2$ (carbon dioxide): Methane is a potent greenhouse gas.

  • Includes a lot of trace gases: Various other gases are produced in smaller quantities.

• Organic and toxic leachate: Liquid that percolates through the waste, containing dissolved and suspended pollutants.

• Low load-bearing capacity: Landfills are unstable and cannot support heavy structures.

• Intensive settling (especially uneven settling): The waste compacts over time, causing uneven settling of the landfill surface.

Landfill Carbon Mass

• Carbon inputs: Degradable and non-degradable materials: Organic materials that can be broken down by microorganisms and inert materials that persist in the landfill.

• Carbon storage: Lignin, biomass, undecomposed cellulose and hemicellulose, etc.: Carbon is stored in various forms within the landfill.

• Outputs: VOCs, $CH<em>4$, $CO</em>2$: Volatile organic compounds, methane, and carbon dioxide are released from the landfill.

Estimated Global Anthropogenic Methane Emissions by Source

• Source: GLOBAL ANTHROPOGENIC EMISSIONS OF NON-CO2 GREENHOUSE GASES, 1990-2020 (EPA REPORT 430-R-06-003).

Avoidance of $CO_2$ Emissions

• Comparing different waste disposal technologies: Assess the greenhouse gas emissions associated with various waste treatment methods.

Emissions of $CO_2$-Equivalents from Landfills

• Content of biologically degradable material for landfilling (BMW): The amount of organic material in landfills affects methane emissions.

What is Composting?

• Composting is the controlled aerobic biological decomposition of organic matter into a stable, humus-like product called compost: This process requires oxygen and is managed to optimize microbial activity.

• It is essentially the same process as natural decomposition except that it is enhanced and accelerated:

  • By mixing organic waste with other ingredients to optimize microbial growth: Adding materials with different C:N ratios to balance the mix.

  • By controlling and creating optimal conditions for the micro-organisms (aeration, regulation of the water balance): Maintaining proper moisture and oxygen levels to promote decomposition.

Composting

• Aerobic decomposition of organic materials in a thermophilic temperature range: High temperatures are essential for sanitization.

• High temperatures are necessary to kill weed seeds and organisms that cause disease in humans, plants, and animals (sanitized compost): Ensures the compost is safe for agricultural and horticultural use.

• Agricultural and horticultural use is a good way of reclaiming nutrients from organic refuse to improve the condition of soils: Compost improves soil structure, water retention, and nutrient availability.

• A good and usable compost can only be produced out of separately collected organic wastes!: Contamination is minimized when organic waste is collected separately from other waste streams.

Composting - Aerobic Respiration

• Aerobic micro-organisms use molecular oxygen ($O_2$) to liberate the bulk of the energy from the carbon source: Oxygen is essential for the decomposition process.

• $[C,O, 4H] + O<em>2 \rightarrow CO</em>2 + 2H_2O + Energy (Temperature)$

• AEROB DECOMPOSITION: $C<em>6H</em>{12}O<em>6 + 6 O</em>2 \rightarrow 6 CO<em>2 + 6 H</em>2O$ Energy = – 2.875 kJ/Mol HEAT!

Close the Natural Circle of Life

• To compost materials means also to close the natural circle of life: Nutrients are returned to the soil, supporting plant growth.

• Reduce the use of mineral fertilizer: Compost provides essential nutrients, reducing the need for synthetic fertilizers.

• Compost as a source to provide:

  • Nutrients for the plants: Compost contains essential elements such as nitrogen, phosphorus, and potassium.

  • To adjust the soil conditions: Improves soil structure, water retention, and aeration.

  • Humus (organic matter) source: Humus enhances soil fertility and supports microbial life.

Reasons for Composting

• 40% or much more of produced waste (MSW) is from organic origin: A significant portion of municipal solid waste is organic and can be composted.

• Organic components in landfill cause higher gas (mainly methane) and leachate production and instability of waste body: Composting reduces the amount of organic waste in landfills, mitigating these problems.

• Composting is a sustainable method to use biological resources with a useful and environmental aim: It converts waste into a valuable resource and reduces environmental impact.

Composting - Basics of Composting

• Composting is a Microbial Process: Microorganisms break down organic matter.

Composting Microbes

• Bacteria: Decompose a wide range of organic materials.

• Fungi: Break down complex organic compounds, such as lignin and cellulose.

• Protozoa: Control bacterial populations and contribute to nutrient cycling.

• Actinomyces: Decompose tough organic materials and give compost its earthy smell.

Primary Needs of Composting Microbes

• Carbon - for carbohydrates for energy: Provides energy for microbial activity.

• Nitrogen - for nutrients and proteins to build biomass: Essential for microbial growth and reproduction.

• Some other nutrients (P …): Phosphorus and other micronutrients are necessary for microbial metabolism.

• Oxygen - for aerobic respiration: Oxygen is required for aerobic decomposition.

• Moisture - necessary for biological functions: Water is essential for microbial activity and nutrient transport.

• pH – an initial range of 5 to 8 is preferable: Optimal pH range for microbial activity.

Recommended Conditions for Rapid Composting

The Composting Process

• (Leslie Cooperband; University of Wisconsin-Madison; 2002)

Stages of Composting Operation

• Stages of Composting Operation: Initial decomposition, thermophilic phase, cooling phase, and maturation phase.

Proper C:N Ratio

• Necessary to optimize composting conditions: Balances carbon and nitrogen for efficient microbial activity.

• C:N = 30:1 to 40:1 is optimum for composting: Provides the ideal balance of carbon and nitrogen for microbial growth.

• If C:N < 20:1, odors occur and nutrients may be lost: Excess nitrogen leads to ammonia release and odor problems.

• If C:N > 40:1, composting process slows down: Lack of nitrogen limits microbial growth and slows decomposition.

Carbon : Nitrogen ratio (C:N) of compost materials

• Dairy manure 20:1

• Sheep manure 14:1

• Poultry manure 10:1

• Humus 10:1

• Vegetable wastes 12:1

• Seaweed 19:1

• Straw 80:1

• Corn stalks 60:1

• Leaves 45:1

• Alfalfa 13:1

• Legume/grass hay 25:1

• Grass hay; garden waste 80:1

• Rotted sawdust 200:1

• Fresh sawdust; wood 500:1

• Paper 170 - 800:1

Question

• The compost organisms work best at a C/N of 25:1 - 35:1

• How can this C/N ratio be achieved? By mixing carbon-rich and nitrogen-rich materials in appropriate proportions.

C/N Ratio Change Over Time

• C/N Ratio change over the composting time: The C:N ratio decreases as carbon is converted to carbon dioxide.

Important Parameters During Composting Process

• Air (oxygen): Essential for aerobic respiration.

Parameters of the Composting Process

• Oxygen Level:

  • At process start: minimum 3 - 4 %: Ensures aerobic conditions are maintained.

  • Provide a good structure in the pile to ensure a homogeneous repartition of the oxygen (avoid lumps formation): Proper structure prevents anaerobic zones.

  • Poor rotting leads to fermentation processes (anaerobic digestion): Anaerobic conditions result in the production of undesirable byproducts.

  • Odor (hydrogen sulfide ($H<em>2S$), ammonia ($NH</em>3$)): Anaerobic decomposition produces foul odors.

  • Development of gases harmful to the climate (methane ($CH<em>4$) and nitrous oxide ($N</em>2O$)): Anaerobic conditions increase greenhouse gas emissions.

Important parameters during the composting process

• Carbon dioxide / Oxygen: Indicators of microbial activity.

• Degradation and maturation phase: Different phases of composting have varying oxygen demands.

• Degradation phase has high oxygen demand!!: Active microbes need $O<em>2$ and produce $CO</em>2$

• > 3 to 5 % $O_2$ in the compost pile: Maintaining adequate oxygen levels is crucial.

Changes in $CO<em>2$ & $O</em>2$ Concentration without Aeration

• Changes in $CO<em>2$ & $O</em>2$ concentration without aeration: Oxygen levels decrease, and carbon dioxide levels increase in the absence of aeration.

Important Parameters During Composting Process

• Moisture:

  • Aerobic bacteria need moisture to decompose organics: Water is essential for microbial metabolism.

Proper Moisture and Air in Composting Material

• A compost pile needs water because the organisms grow in a moist environment - micro-organisms need water to survive: Moisture supports microbial life.

• However, too much water and organisms drown without oxygen: Excess water restricts oxygen flow.

• 40 % - 50 % moisture content (MC) is optimum to provide organisms with both air and water (depends on material): Ideal moisture range for composting.

Structure - Proper Particle Size

• Porosity affects aeration: Particle size influences air flow within the compost pile.

Average Moisture Content during Compost Process

• Average Moisture Content during Compost Process: Moisture levels fluctuate during different stages of composting.

Mix Well; Do Not Compact

• Mix carbon & nitrogen materials together to provide a balanced diet: Ensures all microorganisms have access to necessary nutrients.

• Add water if the mixture is too dry; or add more dry materials if the mixture is too wet: Adjust moisture levels as needed.

• Do not compress/compact the mixture; keep space for air to flow in the compost Pile: Compaction restricts oxygen flow.

Question

• Why was water added? To maintain optimal moisture levels for microbial activity.

• How do you control the water content in the compost heap? By monitoring moisture levels and adding water or dry materials as needed.

• How do you increase the water content? By adding water or wet organic materials.

Process Factor - Temperature

• Active aerobic organisms are the reason for the production of thermal energy: Microbial activity generates heat.

• The temperature influences the degeneration process mainly the speed of degeneration because the general rule is that the activity of micro-organisms rises with an upgrowing temperature: Temperature affects the rate of decomposition.

• Hygienisation: High temperatures kill pathogens and weed seeds.

Temperature Changes in a Compost Pile

• Important to monitor; very easy to measure; shows the success of composting: Temperature changes indicate the activity level of microorganisms.

Results of Evaluation - Temperature Profiles

• Temperature profiles during composting: Temperature fluctuations during different stages of composting.

Lag Phase - Bacterial Growth Curve

• Lag phase - time required for the organisms to acclimate to the new environment: Microorganisms need time to adjust to new conditions.

• No increase in the number of viable cells (period of active growth without cell division and cells for preparation): Initial phase of slow growth as organisms prepare for rapid multiplication.

Process Factors - Aeration

• Supply with oxygen to keep the micro-organisms alive (aerobe decomposition): Oxygen is essential for aerobic respiration.

• Taking away the carbon dioxide: Removes inhibitory byproducts.

• Reduction of water content (dry the material!): Aeration helps to dry out excessively moist materials.

Changes in $CO<em>2$ & $O</em>2$ Concentration without Aeration

• Changes in $CO<em>2$ & $O</em>2$ concentration without aeration: Oxygen levels decrease, and carbon dioxide levels increase in the absence of aeration.

Process Factor - Temperature

• Why does a well-working compost heap get warm? Microbial activity generates heat during decomposition.

• How do you control the temperature in the windrow and how often? By turning the pile and monitoring temperature regularly.

• What is the relevance of the temperature in the windrow for the compost product? High temperatures ensure sanitization and rapid decomposition.

Process Factor - pH – Level

• The activity of the micro-organisms is closely related to the pH – Level of the input substrate: pH affects microbial activity.

• pH influence availability of nutrients: Nutrients are more available within an optimal pH range.

• Good for biological activity are pH - Levels between 5.5 and 8: Ideal pH range for composting.

• Too low-pH conditions are a frequent process problem in food waste composting!: Food waste can lower pH, inhibiting microbial activity.

Monitor the Compost Process

• Temperature – the primary way to determine if the micro-organisms are healthy: Monitoring temperature indicates microbial activity.

• Moisture & air – easily assessed by inspecting the quality of the compost pile: Visual inspection can reveal moisture and aeration issues.

• Smell – odor is a key indicator of whether composting is progressing properly: Foul odors indicate anaerobic conditions.

The Composting Process

• (Leslie Cooperband; University of Wisconsin-Madison; 2002)

Two Types of Materials Are Needed

• Dry Organic Materials:

  • Are high in carbon & low nitrogen: Carbon-rich materials provide energy for microbes.

  • Tend to be dry: Dry materials help balance moisture content.

  • Have the structure to allow aeration: Structural materials create air pockets for oxygen flow.

  • Carbon is the primary food for composting organisms: Microbes use carbon for energy.

  • Includes such materials as wood chips, brush, and tree trimmings: Examples of carbon-rich materials.

• Wet Organic Materials:

  • Are high in nitrogen & low in carbon: Nitrogen-rich materials provide nutrients for microbes.

  • Have a high moisture content: Wet materials add necessary moisture.

  • Nitrogen is the primary building block for composting organisms: Microbes use nitrogen to build biomass.

  • Includes such materials as grass, fruits, vegetables: Examples of nitrogen-rich materials.

Unsuitable Input Materials

• Recyclable materials: Plastics, glass, and metals should be recycled, not composted.

• Harmful substances: Chemicals, pesticides, and heavy metals can contaminate compost.

Totally Unsuitable Materials for Composting

• Totally Unsuitable Materials for Composting: Plastics, metals, glass, chemicals, and diseased plants.

Suitable Input Materials

• Organic Kitchen Waste: Vegetable scraps, fruit peels, coffee grounds, and eggshells.

• Organic Garden Waste + Agricultural Waste: Grass clippings, leaves, plant trimmings, and manure.

Composition of the Input Material

• Easiest composition by volume is to mix wastes without structure (mostly with narrow C/N-ratio) with structure material (wide C/N-ratio): Balances carbon and nitrogen and provides aeration.

• Because the biowaste characteristics are quite different, it is not possible to give exact numbers about a suitable composition of the input materials: Material composition varies depending on the source.

Proper Particle Size

• Breaking large pieces of materials into small pieces will increase the surface area where micro-organisms can live and feed: Smaller particles increase decomposition rate.

• This speeds up composting.

• Not too big and not too small - a mixture of 1 – 10 cm size materials is ideal: Provides optimal surface area and aeration.

• Pieces that are too small will not allow fresh air to flow through it: Excessively small particles restrict aeration.

Structure - Proper Particle Size

• Porosity affects aeration: Particle size influences air flow within the compost pile.

Putting the Fundamentals into Practice

• A correctly built and managed composting pile will:

  • Reach high temperatures: Indicates active decomposition.

  • Destroy weed seeds: High temperatures kill weed seeds.

  • Control pathogens: High temperatures sanitize compost.

  • Avoid odor problems: Proper aeration prevents foul odors.

  • Produce finished compost in 2 – 3 months: Optimal management accelerates decomposition.

Operation Quality and Product Quality

• Hygienic harmlessness: Ensures compost is safe for use.

What is Sanitising (Hygienisation, Pasteurisation)?

• Sanitizing treatment shall mean: biotechnological treatment of biodegradable materials for sanitation purposes- pasteurization:

  • aerobic sanitizing treatment (thermophilic composting): Uses high temperatures to kill pathogens and weed seeds.

  • anaerobic sanitizing treatment (thermophilic anaerobic digestion): Uses high temperatures in the absence of oxygen to sanitize.

  • any other form of sanitizing treatment: Other methods that achieve the same level of sanitation.

Putting the Fundamentals into Practice

• Managing the composting operation to optimize conditions requires many things:

  • Site selection and design: Proper site selection and design are essential for efficient operations.

  • Composting methods: Choosing the right method for the materials and site.

  • Equipment and staffing: Adequate equipment and trained personnel are needed.

  • Operational controls: Monitoring and adjusting parameters to optimize conditions.

  • Monitoring & recordkeeping: Tracking temperature, moisture, and other factors.

  • Site maintenance: Keeping the site clean and organized.

  • But first, regulatory compliance: Adhering to local and national regulations.

Repetition and Application - Compost Technology

• Repetition and Application - Compost Technology: Reinforcing key concepts and practical applications.

The Composting Process

1. Collection: Gathering organic waste.

2. Sorting: Removing unsuitable materials.

3. In-Vessel Composting: Composting in enclosed containers.

4. Open Windrow Composting for Green waste: Composting in long piles for yard trimmings.

5. Screening and Grading: Separating compost by particle size.

6. Compost: Finished product ready for use.

Systematic Waste Separation

• Systematic waste separation: Sorting waste at the source to improve compost quality.

Separate Collection Germany – Rural Area

• Collection systems: Curbside collection, drop-off centers, and community composting programs.

Separate Collection in Germany - Collection Systems

• Curbside System:

  • systematic collection- container/sack systems and equipment, vehicles specially designed for container systems

  • unsystematic collection- special containers and/or vehicles

• Bring Systems- depot containers

  • occasionally depots present for green waste

Principal Set-Up of a Composting Facility

• WASTE + Additives + Air -> COMPOST + Residues

• Delivery, Storage -> Pre-treatment -> Mixing -> Rotting -> Post-treatment -> Residues

• Process-Exhaust Air -> Air Treatment

• Process water -> Water Treatment

Bio-Waste Collection

• Automated side loader: Collects waste from the side of the truck.

• Rotary drum vehicle: Collects and compacts waste using a rotating drum.

• Rear-loader waste collection vehicle: Collects waste from the rear of the truck.

Green Waste - Garden Waste and Kitchen Waste - Bio Waste

• Green Waste - Garden Waste and Kitchen Waste - Bio Waste: Different types of organic waste suitable for composting.

Transportation - Bio Waste Storage (Kitchen Waste)

• Transportation - Bio Waste Storage (Kitchen Waste): Proper storage and transportation prevent odors and contamination.

Garden and Green Waste Storage

• Garden and Green Waste Storage: Storing garden and green waste before composting.

Shredding of Green Waste

• Shredding of Green Waste: Reduces particle size and increases surface area for decomposition.

Drum Screens

• Drum Screens: Used to separate compost by particle size.

Screening, Mixing, and Sorting Out of Impurities (Metals)

• Screening, mixing, and sorting out of impurities (metals): Removes contaminants from compost.

Manual Sorting Out of Impurities

• Manual sorting out of impurities: Handpicking contaminants from compost.

Compost Technology - Composting Methods

• Composting Methods:

  • Closed:

    • Static:

      • Tunnel: Enclosed tunnel with controlled aeration.

      • Container: Enclosed container with controlled conditions.

    • Dynamic:

      • Tunnel: Enclosed tunnel with mechanical turning.

    • Quasi dynamically:

      • Floor reactors: Reactors with aeration and turning.

      • Tunnel: Tunnels with partial turning.

    • Encapsulated: Static or Dynamic: Enclosed systems with advanced process control.

  • Open:

    • Windrow composting: Long piles turned regularly.

    • Aerated Static Pile Composting: Piles with forced aeration.

    • Aerated Turned Pile Composting: Piles turned and aerated.

    • Brikollare-methode: A specific method of composting.

    • Tower: Composting in vertical structures.

    • Container: Open containers for small-scale composting.

Thermophilic Phase

• Most intensive phase of rotting: Rapid decomposition occurs.

• decomposition phase: Organic matter is broken down.

• thermophilic bacteria: Bacteria that thrive at high temperatures.

• Sanitation temperature: Temperature required to kill pathogens.

• Sanitation time window: Duration required to sanitize compost.

• High Oxygen demand – Aeration!: Adequate aeration is essential.

• High production of emissions - Encapsulation!: Enclosed systems control emissions.

• High water demand: Moisture is needed for microbial activity.

• In-Vessel Composting: Enclosed systems offer precise control.

• Exhausted Air treatment: Air is treated to remove odors and pollutants.

Composting Systems - Open

• Windrow: Triangular or trapezoidal shaped row of solid waste.

  • Periodically turned by front-end loader or turner: Turning ensures aeration and mixing.

  • Incorporate systems have perforated ducts beneath the long rows for controlled aeration: Forced aeration improves efficiency.

  • Disadvantages are: large land area requirements, high odor potential: Open systems have limitations.

Open Windrow System

• Open windrow system – like backyard composting windrow is normally not covered (plastic foil; membrane textiles).

  1. Chop/Shred waste

  2. Mix different types of waste thoroughly and spread hand-high hoe, shears, shredder

  3. Spread additives (as required)

  4. Moisten if necessary

  5. Add further layers of waste in the same way

  6. Finished compost heap

Windrow Composting

• Windrows of yard debris, manure, and food waste at a composting site: Common method for large-scale composting.

• Combination of the natural aeration and the turning of the windrows: Turning provides aeration and mixing.

Simple Green Waste Composting

• Simple Green Waste Composting: Easy method for composting yard trimmings.

Temperature Profile in the Compost Windrow

• Turning is important!: Turning ensures even decomposition and temperature distribution.

Turned Windrow - Composting Systems

• Turned Windrow - Composting Systems: Systems that involve regular turning of compost piles.

Tractor-Pulled Compost Turning Machine - Sideturn

• Tractor-Pulled Compost Turning Machine - Sideturn: Equipment used to turn compost piles.

Tractor-Pulled Compost Turning Machine

• Tractor-Pulled Compost Turning Machine: Machines used to turn and aerate compost windrows.

Self-Propelled Compost Turning Machines

• Self-Propelled Compost Turning Machines: Machines that move independently to turn compost.

Mechanical and Passive Ventilation

• Turning of compost mix the rotting material (and also aerate): Turning aerates and mixes the compost.

• Passive ventilation with pipes; active ventilation with pipes: Ventilation systems provide oxygen.

Aeration Passively Aerated Windrow System

• Aeration Passively Aerated Windrow System: Systems that use natural air flow.

• HIGH-TEMPERATURE COMPOST HEAP (USING Bamboo for AERATION): Innovative aeration techniques.

Composting Systems – Active Aerated

• Static Pile- Low technology method of