Technology Opportunities

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Technology Opportunities Challenges
First Farrell Institute Forum Capturing Value
from Green Biomass Waste
7th July 2006

• Dr Ron Wainberg
• 0418 427 481
• ronberg_at_ozemail.com.au

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Greenwaste Organic Waste

• Greenwaste Garden Waste
• Prunings, grass clippings, leaves, weeds etc
• Could include forestry wastes such as bark
  sawdust
• Organic waste is much broader
• Largest fraction of solid waste in Australia
  (non- mining)
• Greenwaste
• Food waste
• Wood waste
• Paper / cardboard
• Agricultural waste
• Animal wastes

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The Challenge

• Maximise value from organic waste
• Renewable resource
• Sustainable fuel supply
• Reduction in GHG emissions
• Burning or burying waste impacts air water
• Efficient recycling of carbon and soil macro
  micro-nutrients

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These wastes can be Resources

• Cotton trash
• Bagasse
• Grain residues and straws
• Nut and stone fruit residues
• Weeds
• Animal manure and bedding
• Abattoir waste
• Wool processing waste
• Sawmill forestry waste

• Greenwaste
• Sewage Sludge
• Waste Paper (contaminated)
• Grease trap Oil waste
• Food waste

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Types of Products

• Compost Soil Conditioners
• Fertilisers
• Electricity and Heat

• Industrial Chemicals
• Concrete Additives
• Activated Carbon
• Insulating Materials
• Liquid Fuel
• Solid Fuel
• Biomass Plastic Resin Composites

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Synopsis of the present situation

• We think mainly of compost
• Compost industry is at a crossroads
• Government push to reduce waste to landfill
• Key system driver
• Compost industry grown rapidly - respond to need
  for sustainable resource usage
• Supply push
• Product surplus

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Greenwaste Management Issues

• Market for the product
• Costs transport and processing
• Technology
• Contamination
• Operator skills

PRIMARY
SECONDARY
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Greenwaste Management Issues

• Market for the product
• Costs transport and processing
• Technology
• Contamination
• Operator skills

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Alternative Waste Processing

• Waste management without landfill
• Three broad approaches
• Mechanical Separation
• Biological Treatment
• Thermal Treatment
• Combination Integrated Solid Waste Management

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Biological Treatment

• Transform / stabilise organic waste
• Need to separate the non-organic fraction
• Contamination issues
• Lignocellulose responds slowly

• Three broad process types
• Composting
• Vermicomposting
• Anaerobic Digestion

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Natural Processes

• Aerobic and Anaerobic
• Natural recycling of dead plant animal matter
• Bacteria and invertebrates in the soil/water
• May be slow depends on prevailing conditions
• For example, composting
• Decompose to humus ? recycle nutrients in the
  ecosystem
• End products CO2 / H2O / Heat / Humus
  (relatively stable organic end product)

Engineered Processes

• Accelerate what nature does
• Treat food and greenwaste
• Potentially process 50 of urban waste
• Conserve resources

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Composting Process

• Aerobic biological process plenty of oxygen
• Time and temperature destroy pathogens/weed seeds

• Types of processes
• Static pile
• Proprietary in-vessel systems

• Things to watch
• Temperature
• Moisture
• CN Ratio
• Surface area
• Aeration oxygen levels

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Commercial Composting Systems
Mechanical Turning
Open Windrow Composting
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Proprietary Composting Systems

• The VCU is an example of an enclosed Composting
  System

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Tunnel Composting
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Autoclave Systems

• Pressure and heat
• Break down organic fraction
• Sterilise material
• Reduce plastics volume
• Enhanced separation of components

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Biological Treatment - Vermicomposting

• Commercial worm farms
• Extended beds to spread material
• Care with speed of feed addition
• Maintain correct conditions to foster worms
• New material added at top of the bed
• Vermicast removed from base mechanical scraper
• Products soil enhancer and protein

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Digestion Processes

• Anaerobic biological process starved of oxygen

• Completely different to composting
• Bacteria
• Methane production energy recovery
• Endothermic
• Odours
• Unpleasant or toxic by-products
• Residual material needs treatment

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Bioreactor Landfills

• Digestion in a vessel not practical for bulk
  urban waste
• Buried organic material degrades naturally
• Eg marsh gas or coal mine gas formation
• Landfill need not be only a simple waste
  repository
• Bioreactor Landfills control the process and
  accelerate waste decomposition rate
• Collect and recirculate leachate
• Maintain chemical and biochemical environment

• Benefits
• Enhanced short term gas yield ? energy recovery
  more economic
• Faster waste stabilisation ?reduced aftercare
  costs
• Conservation of landfill space ? additional waste
  disposal
• Improved leachate management ? collect and
  recirculate

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Bioreactor Landfills

• On-going work to overcome practical difficulties
• Excellent lab results are equivalent to huge
  quantities of leachate
• Realistically leachate recirculation rates are
  orders of magnitude lower
• Stabilisation time an order of magnitude greater
   
• Design requirements to achieve uniform leachate
  distribution
• Effect of plastic bags
• Rapid degradation ? movement of the waste bed
• Void volume can be reclaimed
• Damage leachate and gas lines
• Effect of high compaction rates
• Care when laying waste in place
•  Build as a series of self-contained cells

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Thermal Treatment

• Direct combustion processes
• Fuel burnt directly
• Energy recovered as heat, electricity or both
• Process Engineered Fuel
• Combustion
• Co-firing

• Indirect combustion processes
• Thermal treatment to an intermediate product
• Energy recovered later
• Pyrolysis
• Gasification

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Process Engineered Fuel

• Waste materials as process fuel by itself or with
  fossil fuel
• Environmental considerations
• Strict emission standards have to be met
• Foremost role in obtaining regulatory approval
• Waste variable quality and variable sources
• Burning uncontrolled mixed wastes a hard
  political sell!
• Conversion to Process Engineered Fuel
• Opportunity to control the quality
• Remove much of the risk of poor combustion
  emissions
• Manage problems with materials handling and
  equipment fouling

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Process Engineered Fuel

• Briquettes manufactured from suburban greenwaste
  by high pressure extrusion

Shredded suburban greenwaste
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Raw Material prior to Extrusion (hard or
softwood)  Moisture Content                  
  8  Average Particle Size             
 2-6mm  Bulk Density                           
c. 200 kg m3  After Extrusion  Moisture
Content                     4  Bulk Density   
                        c . 1400 kg m3 
Calorific Value                         4870 kcal
(8400 btu/lb)  Ash Content                    
        0.35-0.5
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Liquid Fuels

• Biodiesel
• Derived from fats and oils
• Ethanol
• Fermentation of sugar
• Purification requires energy
• Emerging lignocellulose technology
• Enzymes
• Molecular sieves

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Combustion

• Incineration is not a popular option in
  Australia
• Significant community resistance to previous
  projects

• Positives
• 80 90 volume reduction in material requiring
  ultimate disposal
• Potential for energy recovery
• Destroy hazardous material which should no go to
  landfill
• Medical wastes, persistent toxic organic
  compounds (HCB, PCB, halogenated organic
  compounds etc)

• Negatives
• Hazardous gas emissions
• Requires careful control
• Sophisticated gas cleaning
• Combustion mobilises metals
• Ash is hazardous secure disposal
• High capital cost
• Financial viability requires on going supply of
  waste feedstock
• Discourages waste minimisation initiatives
• Resource inefficiency

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Incinerations image
A landfill in the sky
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Pyrolysis

• Not new
• Charcoal manufacture by wood pyrolysis
• 19th Century process to supply coal gas for
  lighting
• Heat biomass with low O2 to 850oC
• Remove and destroy biomass volatile components
• Residual carbon is unaffected - insufficient
  oxygen to oxidise it

• Biomass decomposition products
• Char (carbon such as charcoal or coke)
• Can be used as fuels elsewhere
• Pyrolysis Gas - high calorific value
• Composition varies - largely H2 CH4 traces of
  hydrocarbons, CO, CO2, and N2
• Fuel boiler or engine (remove particulates and
  tars)
• Oils and Tars
• Can be a problem to manage
• Source of a wide range of organic compounds 

Pilot pyrolysis plant. (Capacity 300 Kg/hr
Biomass.) Photograph courtesy of Biomass Energy
Services and Technology Pty Ltd.
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Gasification

• Confused with pyrolysis
• Completely different conditions
• Heat biomass gt 850oC
• Controlled quantities of air (or O2) and steam
• Crack tars and oxidise carbon residue
• Endothermic process
• Produces combustible gas ash.
• Gasification with air ? producer gas
• Gasification with O2 ? synthesis gas
• Synthesis of industrial chemicals
• CO CO2 H2 ? Methanol

Typical composition comparison dry basis
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What are the drivers?

• Public health social amenity
• Traffic
• Noise
• Dust
• Odour
• Perceived environmental impacts
• Sustainability of resource usage
• Poor community support for new landfills

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Not in my backyard(NIMBY)

• Natural bias
• Technical sophistication
• Not second nature
• Proponents can appear arrogant
• Must involve communities from the start
• Not here is the answer to your problem

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Conclusions

• Potential value in Waste organics
• Renewable resource
• Possibilities well beyond simple compost
• Industrial chemicals
• Powerful soil enhancers
• Solid and liquid fuels
• Technology development dynamic and ongoing
• Integration
• Technology need is NOT the limiting factor
• Limited by thinking conventionally