Organic waste, or green waste, is organic material such as food, garden and lawn clippings. It can also include animal and plant based material and degradable carbon such as paper, cardboard and timber.
Burying organic waste in landfill is a big problem and it’s not just because of the resources we lose. When organic waste is dumped in landfill, it undergoes anaerobic decomposition (because of the lack of oxygen) and generates methane. When released into the atmosphere, methane is 25 times more potent a greenhouse gas than carbon dioxide.
Methane is, however, also a valuable resource. The natural gas piped into our homes is primarily methane. Organic waste can also be treated to make compost and soil conditioning products, as many people do in their backyards and gardens.
Victoria is about to invest in a range of new resource recovery technologies. These high-tech Alternative Waste Treatment Facilities (AWT) will improve the amount of resources we can recover from our waste.
This includes dedicated facilities to recycle organic waste (green AWTs) as well as facilities to sort and recover material from a broader range of waste streams (dirty AWTs).
It takes a lot of money to develop these facilities and it doesn’t cost a lot of money to simply send waste to the dump. Investment in these new facilities is only likely to happen if there is an increase in the landfill levy.
In addition, the development of these facilities could create an incentive to maintain the amount of waste generated, if other measures aren’t taken as well.
We believe that Victoria should only invest in new waste treatment facilities if they are used together with a range of waste reduction and resource recovery measures. Combined, these measures would provide incentives to producers and manufacturers to design better products and move us towards more sustainable production and consumption.
New landfills are currently lined with a membrane created to capture methane in liquid form. They’re unable to capture all the methane generated, however, and they don’t allow us to recover the organic resources lost.
Open window or tunnel composting has also been used for recycling organic waste. These systems use aerobic (with oxygen) digestion that doesn’t produce methane. However, these facilities aren’t able to treat food waste and often have considerable odour problems.
In-vessel composting is also a form of aerobic treatment that takes place in a closed container. It provides optimum conditions for micro-organisms to break down organic waste and can more easily handle food waste.
Other treatment processes use anaerobic digestion in a confined space that allows for the capture of the methane produced. This methane can then be used as energy from waste to either generate electricity or provide heat for the composting process.
We believe that organic waste should be banned from disposal to landfill. We also support the widespread development of dedicated organic waste treatment facilities – green AWTs – that are able to treat the broadest range of degradable organic carbon.
There are also options for the development of facilities to separate recyclable and non-recyclable material. These facilities – dirty AWTs – are often extremely high-tech and employ a range of methods to extract the material. These include trommels, magnets, lasers and fluid bed.
Dirty AWTs often have an organic waste treatment facility embedded into or parallel to the facility. They offer the ability to increase the resource recovery rate from waste without being dependant on sorting the materials at the place of disposal. However, this often leads to a lower grade of recycled material. It can be particularly problematic with the extraction of organic material from dirty AWTs.
We support the development of dirty AWTs to service areas where the source separation of organic material is difficult – such as the inner suburbs of Melbourne – and for processing residual waste in other municipalities.