Vast amounts of plastic packaging on the market today could be eliminated completely. However, in certain applications like food and medical equipment, the physical protection they afford is vital.
Plastic is almost unparalleled in offering a low-cost, lightweight barrier that maintains hygiene and prevents waste. Using bioplastics instead of oil plastics in these essential applications can lower the ecological and carbon footprint of the packaging. Yet what happens to the material at the end of its life is an important design consideration in limiting its environmental impacts.
Often, designing for sustainability focuses on the start of the bioplastics lifecycle, where renewable feedstock offers emissions savings over oil plastics. However, what happens at the end of the product lifespan matters just as much in limiting its environmental impacts.
Recyclability and natural biodegradability are the two essential criteria that make bioplastics packaging truly sustainable. A recyclable plastic reduces the need to draw on virgin feedstock, making resource use more efficient. One that also degrades quickly and safely in the natural environment prevents it from adding to the plastic pollution problem caused by oil plastics.
Yet very few bioplastics on the market hit both criteria. Even when bioplastics are recyclable, specialised plants that handle bioplastics are not widely available. This means that just like oil plastics, bioplastics can enter and linger in the environment as landfill waste or litter. Even where they eventually break down, some can release eco-toxic compounds.
Full Cycle Bioplastics and Polymateria stand out in the bioplastics and circular packaging industry for offering materials that are recyclable whilst also degrading harmlessly in the environment if they escape the waste processing stream.
Harvesting PHA from microbes
Californian startup Full Cycle Bioplastics, along with partners Elk Packaging and Associated Labels and Packaging, have created a compostable polyhydroxyalkanoate (PHA) made from agricultural byproducts and food waste.
PHAs, including the one produced by Full Cycle and partners, are substitutes for petrochemical multi-layer packaging film found around many everyday consumer items like food and laundry detergent.
Full Cycle’s version is recyclable and biodegradable in marine environments, properties that won it the 2018 Ellen MacArthur Foundation’s Circular Materials Challenge at the World Economic Forum in Davos.
Full Cycle starts by collecting their organic feedstock from industrial sites like compost facilities, anaerobic digesters, landfills, food processors, and large agricultural operations.
From there, they bring the material to production tanks full of wild, non-GMO bacteria.
Full Cycle’s polyhydroxyalkanoates (PHAs) manufacturing process begins when the bacteria in their fermentation chambers chomp on the organic feedstock and metabolises it into PHA, which they store away in their bodies.
These bacteria are not fussy about what they eat and the inputs can be anything from unrecyclable paper to farm waste. Their bodies work on these inputs in the same way to produce a chemically homogenous end product – a PHA that when harvested from their bodies is ready to be customised for different product applications.
As they scale, Full Cycle wants to co-locate its bacterial vats at composting plants, offering an additional revenue stream to companies that produce large volumes of organic waste.
Full circle with microbial recycling
The company is able to take back any products made with their material and feed it once again to the bacteria, which results in virgin PHA.
PHA are a family of biological polyesters that occur throughout the natural world, including in many microorganisms. It functions as a ‘fat store’ in microorganisms, with some species containing up to 90% of the cell dry weight in the substance.
The idea for the microbe-manufactured bioplastic came about when Full Cycle’s founders, twin brothers Dane and Jeff Anderson, sought to tackle the plastic pollution they encountered while bodysurfing.
Two things about Full Cycle’s bioplastic makes it stand out: first, it does not rely on cultivated feedstocks, meaning additional resources like land and fertiliser are not being used to make it. Second, their bioplastic has a circular end-of-life process which means it can get turned into new products.
Polymateria’s programmable plastics
One of the biggest drawbacks of a plastic that degrades easily and quickly is that it can cut short the lifespan of a product. This is fine for single-use cutlery but is a problem for applications where durability is more important. Balancing between a product that remains functional for reasonable periods and one that disintegrates easily under microbial action is difficult.
Imperial College startup Polymateria has solved this problem with a material that has a pre-programmed lifespan. They have come up with a way of structurally modifying polyethylene in a way that keeps the material functional for a set time period before decomposing.
The company works with polyethylene, which belongs to the wider polyolefin family – the most common type of littered plastic packaging. Polymateria currently manufactures their modified polyethylene for consumer applications like bags, flower sleeves, toilet paper bags, bread bags, confectionary wrappers and confectionary labels.
Polymateria sells a drop-in pellet that packaging manufacturers insert into their resin at the start of the production process. After a certain time limit, catalysts in the pellet will begin breaking the plastic product down into a wax-like substance.
Thanks to synthetic probiotics inserted into the pellets by Polymateria, the wax substance that forms after the time limit is up attracts microbes, fungi, and other bacteria which can eat the material and digest it into harmless compounds. The material does not produce any microplastics.
Polymateria’s plastic reliably breaks down in sea or soil but crucially, this process does not begin before a certain time limit chosen by the manufacturer, meaning it remains functional while still in the hands of the consumer.
Polymateria is an interesting example of a company that offers sustainable packaging materials but does not work specifically with renewable materials, although their technology can be applied to bio-polymers too.
Polymateria played a role in shaping a new British Standards Institution standard that sets out clear testing procedures for whether a polyolefin biodegrades fully without leaving toxic traces in the environment. Their own product has passed the standard, having been shown at third party laboratories that their polyethylene films fully biodegraded into water, carbon dioxide, and biomass in 226 days.
Lost plastic that disappears
What makes Polymateria’s innovation special is that it allows plastics to decompose in most natural environments.
While the biodegradation process does not kick in under the sterile conditions of a landfill, their process is designed to work in any natural environment except the polar regions where UV light, air, moisture and microbes set off the chemical process that turns the plastic into bioavailable wax.
The intermediate wax substance that forms after the decomposition trigger sets attracts microbial species that are found in many different habitats. This ability to be broken down by garden variety microbes solves a major problem in bioplastics recycling, where many ‘sustainable’ materials can only break down quickly under artificial conditions inside specialised facilities.
Built-in biodegradability is essential for limiting the ecological impact of plastics that are lost from the waste processing cycle. However, recycling is widely regarded as a more environmentally friendly end-of-life option than composting as forming new products from already-existing plastics cuts back on additional energy and material use.
Polymateria recognises that biodegradability is not a substitute for recycling. In the time before decomposition sets in, their modified polyethylene can still be collected and recycled. The pre-programmed biodegradability trigger is meant to be a solution of last resort that prevents plastics from harming the environment where they do not reach a recycling plant.
Best of both worlds
Petrochemical plastic recycling rates are poor even in the developed world and capacity is even lower for bioplastics. Until the logistics and infrastructure of recycling are improved, the packaging industry must opt for bioplastics that biodegrades without human intervention or toxic effects.
Safely biodegradable plastics still need to be recyclable, however. Even renewable materials can still add to unnecessary feedstock and energy use and the ability to re-use materials already in circulation is essential for cutting the carbon intensity of packaging.
Right now, buyers are under-informed about what they are getting when a material is labelled as being biodegradable. There is no EU law in place that defines what exactly constitutes a biodegradable plastic and the same problem exists around the world.
Demand for recyclable and safely biodegradable plastics can be strengthened by informing the consumer. With clearer laws and guidelines around the testing and marketing of bioplastics, consumers would be better placed to select packaging materials with minimum impact.