1. Solid Waste Management
On completion of this module you should be able to:
Have an overview of solid waste management, including some legislation
Be aware of the responsible solid waste management authorities and some management costs
Define the composition and quantity of solid waste generated
Discuss the collection, transport, treatment and disposal strategies
Have some understanding of hazardous wastes and their disposal methods
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2. Objectives of solid waste management
Safeguarding of public health
Protection of the environment
Transfer and treatment of waste, energy from waste and the conservation of basic materials
Financial limitation of any scheme
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3. Functional elements of waste management structure
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4. Solid waste legislation
Environmental Protection Act 1994
Subordinate legislation referring particularly to solid waste: Environmental Protection Policy - Waste Management
Contaminated Land Act 1991
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5. Waste management hierarchy
Source reduction and reuse are allocated the highest priority
Install recycling programs
Design a suitable treatment system
Residual waste to controlled landfill
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6. Waste management hierarchy
Waste avoidance
Waste reduction
Reuse
Recycling
Energy recovery
Waste treatment
Waste disposal
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7. Reduce, reuse and recycle
Public education and perception on the environment
Household to separate recyclable
Collection agencies to set target for waste reduction
Disposal agencies to reclaim rather than dispose
Industry to favour recycled feedstock
Minimise packaging
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8. Positive aspects of waste reduction, reuse and recycle
Reduces pollution and environmental degradation
Reduces amount of waste to landfill
Saves natural resources
Reduces industry's impact on the environment
Preserves open space used by landfill
Reduces consumer costs
Contributes to a cleaner environment by reducing energy use
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9. Who is responsible for solid waste management?
Local government in collection, treatment and disposal
State agencies involved in quality guidelines
Overriding powers of commonwealth in international issues
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10. Municipal solid waste (MSW) composition
Household or domestic waste
Commercial waste
Builders or demolition waste
Industrial waste
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11. Solid waste generation and cost
Statistical data is paramount in solid waste management
Problem of uniformity in reporting waste generation
Household waste make up about half of total waste stream
National average of MSW is about 776 kg/person.year
Solid waste management average cost is $28/person
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12. Waste composition
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13. Transfer and transport
Siting of transfer station will impact on disposal costs. Facility for efficient collection service by reducing the turn-round times, improves payload, reduces the number of vehicles to the main disposal site
Offers opportunity to implement treatment prior to disposal. Activities may include compaction and baling, shredding and pulverising
Transportation may comprise road, rail and water
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14. Management strategies
Planning essential at outset
Fewer but larger facilities at favourable operating cost
Allow for changing nature of waste generation
Duty of care on waste holders and producers
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15. Management strategies (cont)
Increased powers for waste disposal authorities
Registration of waste carriers
Introduction of polluter-pays principle
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16. Waste disposal options
No single method is appropriate to every type of wastes
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17. Factors to be considered
Analysis of waste stream
Reduce, recovery and recycling viability
Quantity and rate of disposal
Environmental assessment and long-term impact
Collection authority issues
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18. Factors to be considered (cont)
Availability of suitable void space or land
Distance from collection centre
Transfer and treatment facilities
Transportation methods and routes
Overall cost
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19. MSW disposal routes
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20. Controlled landfill
Still the major disposal method but largely dependent on suitable void space
Concepts of attenuate and disperse or containment
Major concerns of landfill
Leachate contaminating groundwater
Landfill gas (methane)
Infestation
Litter, dust
Noise and odour
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21. Steps for implementing controlled landfill
Site selection
EIS, geology/hydrogeology of site
Landfill design (attenuate and disperse or containment)
Leachate collection & treatment, gas utilisation
Site operations
Compaction, stability, leachate and gas monitoring
Site restoration and aftercare
Capping, soil erosion, settlement
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22. Controlled landfill
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23. Controlled landfill
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24. Combustion of MSW Not widely used in Australia
Expensive disposal option involving high maintenance costs
Products are energy, flue gas and solid residues
Residues represent 10% by volume and 25% by weight of input
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25. Types of combustion Incineration of 'as received' waste
Refused derived fuel in grate combustion
Pyrolysis
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26. Mass combustion
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27. Potential environmental concerns of stack gases
Particulates
Carbon dioxide, carbon monoxide
Acid gases (HCl, HF, SO2, NOx)
Heavy metals (Hg, Cd, Zn, Cu, Ni, As, Mn)
Products of incomplete combustion (PICs)
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28. Refused derived fuel (RDF)
Coarse RDF
Fluff RDF
Pelletised RDF
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29. Coarse RDF Feed subjected to pulverisation Removal of ferrous metal
Result in smaller particle size
More uniform fuel
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30. Pulverising, shredding equipment
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31. Air classification
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32. Fluff RDF Lower moisture and metal contaminants Higher calorific value
Lower ash residue after combustion
Used usually in dedicated combustors
High bulk density results in high transport cost
Short storage period
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33. Magnet separators
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34. Pelletised RDF Fluff RDF after compression into discrete form
Can be stored for extended periods
Replace coal in boiler market place
Smaller plants may lack suitable emission control
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35. Pyrolysis Combustion in the absence of oxygen
Produces gaseous, liquid and solid fuels
Endothermic process requiring external heat source
Limited to processing specialist waste
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36. Composting Composting is controlled bioxidative process involving:
Heterogeneous organic substrate in the solid phase
Passing through a thermophilic phase and temporary release of phytotoxin
Production of CO2, water, minerals and stabilised organic matter
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37. Managing composting at 3 levels
At source through household education
Organic material separated at source requiring a separate collection system
Centrally separated by mechanical processing, requires a sophisticated processing infrastructure at transfer station
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38. Important composting criteria
Bulk density increases from 0.35 to 0.6 t/m3 as organic matter is reduced
Maintain free air space of % for aerobic activity
Size to maximise surface area and to permit air flow
Initial moisture 65% to 40% towards the process end
Temperature for exothermic process o C
to reduce pathogens, pests, seeds
controlled by air flow and material turning
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39. Important composting criteria (cont)
Carbon:nutrient (C:N) ratio of 30:1 - 15:1 for rapid aerobic growth
High ratio is detrimental to plants and low ratio releases odour
Tendency for ratio to fall from fresh to mature compost
Final product pH should be about 7 - 8
Contaminants of concern are heavy metals
Pathogens - maintain and control high temperatures to maximise destruction of pathogens and minimise health risks
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40. Hazardous waste
Defined as hazardous because of its quantity, concentration or physical, chemical, infectious properties that may
increase or cause mortality, illness
present a hazard to human, health or the environment when improperly treated, stored, transported or disposed
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41. Hazardous waste (cont)
It may also be defined according to other attributes of:
reactivity ie unstable substances
ignitable substances
corrosivity ie 2 < pH > 12.5
toxicity when ingested or absorbed
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42. Hazardous waste management
Cradle-to-grave management technique
Control at a national level
Waste minimisation
Recycle and recovery
Treatment and incineration
Land disposal
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43. Transport and storage of hazardous waste
Transport and tracking system with a manifest document to accompany any waste
A permitting system to ensure safe operation to treat, store or dispose
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44. Treatment and disposal of hazardous waste
Solidification
Chemical treatment
Incineration
Landfill
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