28/10/2026
When compostable plant-based plastics first came out many years ago, we tossed pieces of a number of these (packaging, cups and containers) into our YOLO Compost Tumbler. They did not compost. While these plant-based plastics can, in theory, compost, this only takes place under industrial conditions.
Interesting insights in this article on Daily Maverick.
"Plant-based plastics fall into two distinct groups: bio-based “drop-in” plastics (Bio-PET) and compostable biopolymers (PLA and PHA).
Bio-PET is derived from sugarcane ethanol rather than crude oil, effectively replacing fossil feedstocks with renewable plant materials. But its final molecular structure is chemically identical to standard, traditional plastic (PET). It behaves like conventional plastic: recyclers can melt and reprocess it, but if it ends up on a roadside or buried in a landfill, it will exist there for centuries. It cuts fossil carbon at the source, but it does nothing to prevent plastic pollution.
On the other hand, PLA and PHA are made from fermented plant starches, like corn or cassava, and can naturally break down into water, biomass and carbon dioxide, but only under specific conditions.
In reality, most PLA and PHA only break down properly under industrial composting conditions. This means they need sustained temperatures of 58°C to 60°C, specific humidity levels, and regulated aerobic microbial activity to break down. Home composting cannot provide these conditions."
What about industrial composting, you ask?
"Although compostable plastics such as PLA offer green alternatives, the country possesses virtually no municipal industrial composting facilities capable of handling post-consumer packaging at scale."
With roughly 440,000 tonnes of plastic leaking into South Africa’s environment every year, plant-based packaging is often championed as an eco-friendly cure-all. But as Council for Scientific and Indu…