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2020/09/15
How green are compostable plastics? (part 2 of 3)
How green are compostable plastics?
Source from: https://renew.org.au/renew-magazine/reuse-recycling/how-green-are-compostable-plastics/
What are the potential benefits of compostable plastic?
There are some circumstances in which compostable plastic could work very well. Richard says that situations in which one entity has control of the entire life cycle of a product could offer a good application. At a sports stadium or a music festival, a hamburger wrapper would only be needed for a short period of time. The material would be chosen by the organisers who can also make sure that wrapping ends up in the correct composting stream along with the food waste. This kind of closed system—from use to disposal—is crucial to the success of a product like this.
“For an almost identical hamburger wrapper served at a take-away restaurant, there’s very little guarantee that the wrapping will reach the right waste stream, especially if the consumer is not even informed about the necessary disposal pathway,” Richard says.
Compostable plastic could also be useful in limiting food waste going to landfill, by encouraging people to bag their food scraps and send them to an industrial composter (as long as that composter accepts the bags).
“If 30% to 40% of domestic waste going to landfill is made up of food waste, which will produce methane, then doing everything possible to reduce this drastically is important,” Mike says. “Encouraging people to collect food waste for green bin collection by distributing certified compostable bags to ratepayers will do this, as well as reducing contamination in the composting stream from non-compostable plastics used to store food waste.”
Another application involves scenarios in which plastic is highly likely to end up in the environment. ’Ghost fishing’, in which lost nets or traps continue to catch fish, is a huge problem in marine environments. Making fishing nets out of compostable plastic is unworkable, as it will undermine their longevity and effectiveness. But Richard says that compostable plastic cable ties on lobster pots, for example, could be a solution.
“If the pot was lost at sea, those ties would degrade in a season and the pot would no longer function to catch lobster,” he says. As long as the fisherman holds onto the pot, the cable ties can be renewed the next season to make it functional again.
Mulch film—plastic laid across the top of soil in industrial agriculture to limit weeds and control soil temperature and moisture—is another, more mainstream application for compostable plastic, Rowan says. Using compostable plastic for this purpose could prevent traditional plastic from breaking down into microplastics in the soil.
Mike believes that there may be wider applications for compostable plastics in replacing plastic that could be contaminated with food. Where it’s necessary to package food with plastic, that plastic can become contaminated and unable to be recycled. If it could be composted along with food waste, that might make a real impact on overall packaging waste. But Mike is careful to point out that this would require industrial composting—few of us have home compost heaps big enough to accommodate all our plastic packaging. And home composting, as it isn’t aerated as regularly as industrial compost and does not reach the same high temperatures, is not as effective at breaking down materials.
However, there may be some applications for home composting plastics as well. Tea bags and coffee pods that contain plastic are already often mixed into home compost heaps (though clearly it would be best to avoid putting plastic in tea bags or using single-use coffee pods in the first place).
“It’s a small amount of plastic and making sure that is degradable could be a good thing,” Richard says.
Overall, it’s all about making sure that the full life cycle of a product is taken into account, and that there is a high likelihood it will end up in the proper waste stream. Otherwise, compostable plastic simply adds more unsustainable products into our environment.
Bin liners are one of the compostable products available.
What do we do with compostable plastic in Australia?
As mentioned above, there is no one answer for what consumers in Australia can or can’t do with compostable plastic. While some states consider all compostable plastic a contaminant in green bins, some individual councils allow compostable plastic of all kinds in their organic waste streams. Adelaide’s City of Onkaparinga accepts many kinds of compostable products in their green waste bins, including cutlery and bags. Other councils in the same city, like Adelaide’s City of Marion, accept only compostable bags. Some councils, like Darebin in Melbourne, accept no compostable plastic at all. Unfortunately, many councils do not currently accept any food waste. New South Wales has the best figures in the country, with 35% of councils accepting food scraps in green bins, according to a 2018 report from the Australian Packaging Covenant Organisation (APCO).
Given this patchwork system of regulations, the most effective way to responsibly dispose of compostable plastic is to talk to your local council or check on their website to see what they accept.
Adopting compostable plastic responsibly
How do we address the many issues with compostable plastic so we can take advantage of the benefits? The two keys are public education and responsible design.
“Consumer engagement and education is massive,” Mike says. Councils, state governments and organisations like ABA dedicating themselves to educating the public about how to use and dispose of compostable plastics can go a long way towards solving the problems we currently face with these products.
Individual producers of compostable products need to take responsibility as well. Products with no clear end-of-life waste stream shouldn’t be produced.
“It’s really important at the design stage that you recognise: what does the consumer or the end user do at the end of the product’s life? How is it going to be disposed of?” Richard says.
Experts agree on the real solution to these problems: stop using so much plastic, especially for single-use purposes.
“The best thing to do is not use plastic in the first place—avoid it where you can,” Mike says. “Where you do need to use it, reduce the amount.”