Over one-fifth of all plastic produced worldwide is tossed into uncontrolled dumpsites, burned in open pits or leaked into the environment. In Australia, 1.1 million tonnes of plastic is placed in the market, yet just 16% (179,000 tonnes) is recovered.
To deal with this mounting issue, the Morrison government last week announced A$60 million to fund plastic recycling technologies. The goal is to boost plastic packaging recycling from 16% to 70% by 2025.
It comes after 176 countries, including Australia, last month endorsed a United Nation’s resolution to establish a legally binding treaty by 2024 to end plastic pollution.
This is a good start – more effective recycling and recovery of plastics will go a long way to solve the problem.
But some plastics, particularly agricultural plastics and heavily contaminated packaging, will remain difficult to recycle despite these new efforts. These plastics will end up being burnt or in landfill, or worse, leaking into the environment.
“Biodegradable” plastic is often touted as an environmentally friendly alternative. But depending on the type of plastic, this label can be very misleading and can lead environmentally conscious consumers astray.
What are biodegradable plastics?
Biodegradable plastics are those that can completely break down in the environment, and are a source of carbon for microbes (such as bacteria).
These microbes degrade plastics into much smaller fragments before consuming them, which makes new biomass (cell growth), and releases water, carbon dioxide and, when oxygen is limited, methane.
However, this blanket description encompasses a wide range of products that biodegrade at very different rates and in different environments.
For example, some – such as the bacterially produced “polyhydroxyalkanoates”, used in, for instance, single-use cutlery – will fully biodegrade in natural environments such as seawater, soil and landfill within a few months to years.
Others, like polylactic acid used in coffee cup lids, require more engineered environments to break down, such as an industrial composting environment which has higher temperatures and is rich in microbes.