Responsible Organic WasteTreatment

Simonne Eldridge

Business Sector Leader –Waste

Tonkin & Taylor Ltd

Waste hierarchy

The value ofgood science

• All decisions should be driven by the wastehierarchy

• Important to make informed decisions based onlocal conditions

Take these teabags

Counter intuitive?

• Putting plastic bottles inlandfill is ok:– For countries with

adequate space and littlerecycling infrastructure,disposing of bottles inlandfill generates a lowercarbon footprint thanrecycling or incineration

– Depends on recyclingoptions and true recovery

Life cycle analysis

• Dutch study in associationwith the TechnicalUniversity of Denmark

• Comparison of lifecycleassessment between loworganic waste andhousehold waste landfills

• Both state of the artfacilities

• Considered impact ongroundwater, soil & air(incl GHG)

LCA conclusions

• Low organic:

– less landfill gas produced but lower collectionefficiency & limited potential for landfill gasutilisation

– can result in significant reduction in potentialenvironmental load

• Household waste with landfill gas utilisationwhere resulting electricity offsets that producedfrom coal out performs the low organic landfillparticularly if include carbon sink

Hyder Report

• LCA comparison of alandfill in Victoria,Australia & fouralternative wastemanagement scenarios:– Aerobic mechanical

biological treatment (MBT)

– Anaerobic MBT

– Waste separation withaerobic compositing offood waste

Other emissionsources considered

• Transport

• Facility construction

• Energy use & energy yields in processing

• Offsets for recovered recyclables

• Organics degradation and storage

Conclusions from aGHG perspective

• Best practice landfill with good performancemanagement sound option for GHGmanagement

• Anaerobic MBT better option than aerobic

• Diversion of household organics to the compoststream has a similar performance to disposal atlandfill (compost used for soil conditioning sodoes not offset use of fertiliser)

• Makes little difference if food waste is collectedweekly or fortnightly

Some factorsto consider

• There is an overall environmental benefit of compostingand applying it to agricultural land if it substitutes forinorganic fertilisers and growth media products.

• This environmental benefit needs to be off set against theemissions associated with cartage of the organic and theresulting compost and the composting process itself

• If compost not used and is deposited in the landfill it cancause problems

• Readily degradable organic waste degrades within theoperational period of the landfill therefore its disposalwould not have any real impact on the life of the landfill.

Some factorsto consider (cont)

• Diverting organics may result in more overall GHGemissions than using greenwaste in landfill to produceelectricity, if the alternative is to produce electricity fromcoal.

• Low organic landfills typically have a lower landfill gascollection efficiency as they tend to be denser therebypotentially increasing the uncontrolled emissions.

• Organics helps to lock up heavy metals in the landfill.

• Incorporation of compost in the landfill cover reducesmethane emissions as the methane is oxidised by thecompost.

However...

• Traditionally managingwaste focus is publichealth

• Multiple lenses nowrequired:– GHG emissions

– Demand for renewableenergy

– Scarcity of naturalresources

• Do not throw away ifcan reuse / recycle

Do not forgetthe waste hierarchy