Looking at alternatives to landfilling
With room for our rubbish running out we think extending the Landfill is the best way forward to manage our waste, but we are testing this assumption by looking at what alternatives are around.
We’ve had some lively debates with the community around these different technologies so though it might be handy to summarise them here for you.
The relatively small size of Wellington and our typography gives us particular challenges when looking into these alternatives. Click here for more information on all alternatives
Conventional (mass burn) incineration Click for further information
This option, which processes waste in a modern incinerator, has provoked quite a bit of discussion during our conversations.
The incinerators typically burn 250,000 tonnes or more of waste per year, and generate energy for heat or power. The Southern Landfill currently only receives about 75,000 of suitable waste per year which could create challenges with a higher relative cost of managing emissions and running the plant.
Issues and costs relate to the amount of waste required possibly impacting waste minimisation measures, the disposal of residual ash, managing emissions, and the disposal of unsuitable materials.
There are no current examples in New Zealand although a plant has been proposed for Hokitika. These methods are common in Asia, Europe, the UK and North America – all using large-scale incinerators.
Advanced thermal treatment Click for further information
This covers a range of technologies including pyrolysis and gasification to achieve thermal conversion of organic materials. Depending on conditions useable outputs include energy, Syngas, Tar/Oil for further refining and others.
Issues and costs relate to pre-sorting the waste, disposal of ash residue, managing emissions and the disposal of unsuitable materials.
There are no examples in New Zealand although trials have been completed for single waste streams (e.g. waste timber) but not general waste. These methods are used in the rest of the world but mostly for specific waste streams (e.g. tyres or wood waste).
Mechanical heat treatment Click for further information
Mechanical heat treatment combines mechanical sorting and heat treatment technologies to maximise the recovery of recyclable, usable material from general waste and processing the remaining waste.
Issues and costs relate to pre-sorting the waste, removal and disposal of recyclable, usable material, costs of disposing of unsuitable materials, and disposing of the output including low quality recyclable material, and stabilised organic material.
There are no examples in operation in New Zealand. There are examples in Australia but the final product is currently landfilled due to environmental regulations in some states. This method is also used in the United Kingdom.
Mechanical biological treatment Click for further information
Mechanical biological treatment is a generic term for an integrated system comprising several mechanical and biological processes which might include removal of recyclable materials, biological reduction of the biodegradable portion using anaerobic digestion and/or aerobic composting.
Issues and costs relate to a material recovery facility to remove unsuitable materials and their disposal, costs of disposing of the output including low quality recyclable material, and stabilised organic material.
There are no examples in operation in New Zealand. These methods are used in Australia New South Wales, Queensland and Western Australia, but in some states the final product is landfilled due to environmental regulations. There are many examples elsewhere in the world – in particular in Europe.