Biodegradable plastics have been causing a bit of hype recently in the green packaging sector. These plastics are being touted as a viable means of reducing the amount of plastics that end up in the world’s oceans. In theory yes, but in practice, no.
For an item of biodegradable plastic packaging to fully decompose it must be entirely composed of natural components. However, most biodegradable products usually contain cornstarch or vegetable oil, these additives compromise the quality of recycled plastics. It is worth mentioning that bioplastics (which are derived entirely from biomass sources) are also non-recyclable as they are intended to degrade and so can’t be used in a recycled polymer. On the other hand, “drop in” bio plastics such as Bio-PET and Bio-PE such as those produced by Braskem can be used in a recycling process. Bio polymers are especially useful in that they capture and fix CO2 from the atmosphere during the growing of the raw material – sugar cane.
A report published by the UN Environment Programme (2015) (links to UNEP PDF) highlights that biodegradable plastics often require prolonged temperatures of around 50C in order to completely break down. These temperatures are rarely found in the marine environment and are usually only found in industrial composting operations.
The adoption of biodegradable plastics also reduces the amount of material being made available for recyclers. By creating a material that can only be used once before being classed as waste, the designers are bypassing the more foundational levels of the waste heirarchy, leaving the public and recyclers little option but to treat the biodegradable plastic as waste rather than a resource that could be reused in another application.
In the UK, we have a fairly good capture rate for plastic packaging from the kerbside with 99% of councils offering a collection as of 2015 (around 75% collect plastic pots, tubs and trays and 20% collect plastic film). In 2016, 45% (1,015,000 tonnes) of plastic packaging was recycled in the UK (BPF) a valuable resource stream for UK recyclers.
For the time being, biodegradable plastics need to be separated from conventional plastics either through a separate collection system or sorting process to divert them to an industrial composting operation. Currently, the benefits of biodegradable plastics above conventional plastics are hard to see. It is in the best interests of society, and in the persuit of a circular economy, for us in the waste industry to improve public awareness of recycling and improve our collection and processing systems. This will go towards ensuring that material is preserved longer than just one lifecycle. By promoting “biodegradable” products, we are selling the public the false idea that they are doing the “right thing”.