Compostable packaging breaks new ground

Bioplastics have largely been written out of European Commission thinking on single use plastics and they are treated the same as conventional polymers in regulation. The waste management industry complains that compostable packaging confuses the public and causes problems for recycling facilities. Yet demand is increasing.  Now we are in Composting Awareness Week, lets look at why more companies are showing interest in bioplastics. 

Polymers made from biomass have a reduced carbon footprint compared with their fossil equivalents. This appeals to brands and consumers who are concerned about climate change. Biodegradable materials that can be easily composted are attractive to governments that are looking for a low-tech approach to waste management.  There is evidence that both of these drivers are increasing in importance. 

Developing countries that have a poor waste management infrastructure are the main source of marine pollution. They can’t afford the sophisticated sorting and recycling infrastructure necessary to deal with waste plastic. Materials that biodegrade in simple composting facilities or in home compost bins offer a way out of the problem. So perhaps for this reason, China has taken a very different regulatory approach from Europe. Biodegradable materials will be exempt from new controls on single use packaging. 

However, composting can be a slow process and the bioplastic industry recommends that it should be carried out at elevated temperature, in an industrial facility. This is certainly true for PLA, the most common biodegradable plastic, but some newer polymers offer simpler end-of-life solutions. Makers of PBS and cellulose based films claim home and soil compostability, with independent certification to prove it.  PHAs are claimed to be biodegradable in marine environments. These materials offer lower technology waste treatment options, at least for flexible films, with the added benefit that if any does escape into the environment it will biodegrade in a reasonable time. 

Consumers who favour renewable, natural and plant-based materials are also attracted to compostable packaging. Composting fits with the concept of ‘organic recycling’ and has the appeal of a ‘natural’ process. Brands that wish to engage with these consumers are increasingly choosing compostable packaging. This is driving both demand and innovation. High barrier laminates that are compostable are now available for specialist food applications. 

NGOs now view bioplastics more favourably. The Ellen MacArthur Foundation has declared its support, providing the biomass feedstock is sustainably produced and that recycled material can’t be used instead. A Plastic Planet, the organisation which campaigns for a plastic-free aisle in every supermarket declares that compostable bioplastics are ‘plastic free’. 

Disadvantages to compostable packaging remain. Both the high cost and lack of availability are barriers to widespread uptake. Set against this, dilution of the expensive biomass inputs with some cheaper petrochemical substitutes already happens for some polymers. Brand owners have also voiced concerns that compostable wrappers and bottles could lead to increased littering if consumers think that they will degrade in the soil.  Compostable plastics must also be broken down with oxygen, by turning or aerating compost so there is no production of methane, a more powerful greenhouse gas than carbon dioxide. 

The complex debate about biodegradable packaging will continue. The situation is also complicated by governments in two of the world’s largest blocks having opposing views on compostable plastics. International companies are faced with the possibility of packaging that differs by region. Into the future, as authorities count the cost of collection and recycling for conventional plastics they may, in the end, favour a more down to earth solution.

Published: 6 May 20

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