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Biodegradation is a chemical process in which materials are metabolised to CO2, water, and biomass with the help of microorganisms.

The process of biodegradation depends on the conditions (e.g. location, temperature, humidity, presence of microorganisms, etc.) of the specific
environment (industrial composting plant, garden compost, soil, water, etc.) and on the material or application itself. Consequently, the process and its
outcome can vary considerably.

Compostable plastics disintegrate after 12 weeks and completely biodegrade after six months. That means that 90 percent or more of the plastic
material will have been converted to CO2. The remaining share is converted into water and biomass, which no longer contains any plastic. No heavy metal contents and no harmful substances should be left behind.

If a separate recycling stream for a certain plastic type exists, the bioplastic material can simply be recycled together with their conventional counterpart – e.g. biobased PE in the PE-stream or bio-based PET in the PET stream – as they are chemically and physically identical in their properties.

The post consumer recycling of bioplastics materials for which no separate stream yet exists, will be feasible, as soon as the commercial volumes and sales increase sufficiently to cover the investments required to install separate recycling streams. It is expected, that new separate recycling streams for PLA for example will be feasible and introduced in the short to medium term.

Compostability is a clear benefit when plastic items are mixed with biowaste. Under these conditions, mechanical recycling is not feasible, neither for plastics nor biowaste. The use of compostable plastics makes the mixed waste suitable for organic recycling (industrial composting and anaerobic digestion), enabling the shift from recovery to recycling (a treatment option which ranks higher on the European waste hierarchy). This way, biowaste is diverted from other recycling streams or from landfill and facilitating separate collection – resulting in the creation of more valuable compost.

Biodegradable and compostable plastic alone will not solve the plastic pollution crisis. Instead, there are many levers that need to be pulled to reduce and reuse plastic and shift to a circular economy. In fact, we can’t even rely on the assumption that these materials will not cause environmental damage if they end up as litter.

All plastic-including biodegradable and compostable types– must be collected and paired with the right recovery systems, so that the material stays in the loop and out of nature.

The key takeaway is that both compostable and biodegradable plastic should only be used when it adds value, makes sense for the product use, and works with the systems that can recover it. We cannot rely on these materials alone to solve the problem. The companies that produce plastic products and packaging, and the people who use them, must also focus on what we know works: reducing and reusing plastic in the first place.