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 Module 10

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 Module 10

Functional elements of waste management structure Module 10

Solid waste legislation Environmental Protection Act 1994 Subordinate legislation referring particularly to solid waste: Environmental Protection Policy - Waste Management Contaminated Land Act 1991 Module 10

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 Module 10

Waste management hierarchy Waste avoidance Waste reduction Reuse Recycling Energy recovery Waste treatment Waste disposal Module 10

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 Module 10

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 Module 10

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 Module 10

Municipal solid waste (MSW) composition Household or domestic waste Commercial waste Builders or demolition waste Industrial waste Module 10

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 Module 10

Waste composition Module 10

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 Module 10

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 Module 10

Management strategies (cont) Increased powers for waste disposal authorities Registration of waste carriers Introduction of polluter-pays principle Module 10

Waste disposal options No single method is appropriate to every type of wastes Module 10

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 Module 10

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 Module 10

MSW disposal routes Module 10

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 Module 10

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 Module 10

Controlled landfill Module 10

Controlled landfill Module 10

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 Module 10

Types of combustion Incineration of 'as received' waste Refused derived fuel in grate combustion Pyrolysis Module 10

Mass combustion Module 10

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) Module 10

Refused derived fuel (RDF) Coarse RDF Fluff RDF Pelletised RDF Module 10

Coarse RDF Feed subjected to pulverisation Removal of ferrous metal Result in smaller particle size More uniform fuel Module 10

Pulverising, shredding equipment Module 10

Air classification Module 10

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 Module 10

Magnet separators Module 10

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 Module 10

Pyrolysis Combustion in the absence of oxygen Produces gaseous, liquid and solid fuels Endothermic process requiring external heat source Limited to processing specialist waste Module 10

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 Module 10

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 Module 10

Important composting criteria Bulk density increases from 0.35 to 0.6 t/m3 as organic matter is reduced Maintain free air space of 30 - 35% 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 50 - 70o C to reduce pathogens, pests, seeds controlled by air flow and material turning Module 10

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 Module 10

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 Module 10

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 Module 10

Hazardous waste management Cradle-to-grave management technique Control at a national level Waste minimisation Recycle and recovery Treatment and incineration Land disposal Module 10

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 Module 10

Treatment and disposal of hazardous waste Solidification Chemical treatment Incineration Landfill Module 10