Greener straws? Bacteria help turn food waste into compostable plastic

What if plastic were made from waste like banana peels instead of petroleum? And what if, after use, that plastic decomposed? A Canadian cleantech startup aims to make that the future of food packaging such as coffee pods.

Toronto-based cleantech startup uses 'the fat of the bacteria'

Luna Yu is CEO of Genecis, a company based at the University of Toronto that aims to turn green bin waste into compostable plastics for use in products like coffee pods. (Craig Chivers/CBC)

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What if plastic were made from waste like banana peels, coffee grounds and cardboard takeout containers instead of petroleum? And what if, after use, that plastic decomposed like the biological materials it was made from?

Toronto-based Genecis, a biotech startup, is trying to make that dream of greener plastic a reality and to make it cheap enough to use in everyday throwaway items like straws, coffee pods and other food packaging.

Genecis harnesses bacteria to turn kitchen waste into compostable, biocompatible plastics called PHAs (polyhydroxyalkanoates).

The plastic-making bacteria eat waste that has been pre-processed by other bacteria into molecular bite-sized pieces. And, like us, if they're well fed, they pack on some extra weight — strangely enough, as plastic.

"It's like the fat of the bacteria," says Luna Yu, the company's 24-year-old CEO.

The plastic granules are later extracted from the bacteria and turned into pellets that can be sold and moulded into plastic products.

The company has signed agreements with Ontario firms that plan to use it to make compostable coffee pods and the plastic that's printed out by 3D printers.

PHA is already on the market. Because it's biocompatible and biodegradable, it's used in lots of medical applications ranging from heart valves to dissolving sutures.

Cheaper and greener

But because it's made from food crops such as sugar cane, corn and canola, it's quite expensive — triple or quadruple the price of petroplastics like PET or polypropylene that are typically used in the coffee pods, drink bottles or yogurt containers we buy.

In this bioreactor at Genecis's lab, bacteria are chowing down on processed food waste and storing the extra energy as plastic instead of fat. (Craig Chivers/CBC)

Yu hopes to reduce the cost of PHA production by at least 40 per cent by using waste as a raw material, making it economically viable for everyday uses like food packaging.

There are other good reasons to do that.

While food crops are renewable resources, agriculture is estimated to be responsible for one-third of the world's greenhouse gas emissions.

We believe … there's no such thing as waste. Waste is a product looking for an opportunity.—  Atul  Bali, Competitive Green Technologies

On the other end of the equation, the kitchen waste we throw out releases carbon dioxide or methane — a greenhouse gas 20 times more potent than carbon dioxide — as it decomposes. Because of that, landfills account for 20 per cent of Canada's emissions of methane. Many municipalities are trying to curb emissions to composting or anaerobic digestion facilities where they can be captured.

David Grewell, a professor at North Dakota State University and director of the Center for Bioplastics and Biocomposites, said turning organic waste into plastic could also lock up or "sequester" those emissions and make waste products more valuable and therefore less likely to end up in a landfill.

"It's going to open up markets and have a positive impact all around," he said.

Genecis isn't the only company trying to make PHAs from waste. Mango Materials in California is using methane from organic waste to make PHAs for plastic bottle caps and biopolyester for clothing. And researchers from AnoxKaldnes in Sweden have been testing a process to make them from sewage sludge.

But all are at early stages, and scaling up is the next challenge.

Right now, at an aging lab that it rents on the University of Toronto's main campus, Genecis can produce about half a kilogram of PHA per week from about 75 kilograms of food waste collected from the cafeteria of a nearby Campbell's Soup factory.

Scaling up

But very soon, it's planning to build a demonstration plant that can process three tonnes of organic waste into up to 70 kilograms of PHA per week with new investment that will allow it to buy more efficient equipment.

In September, Yu was named one of six finalists in the MaRS Women in Cleantech Challenge sponsored by Natural Resources Canada, earning $300,000 in support from MaRS, a Toronto-based tech incubator, along with an annual $115,000 stipend for 2.5 years and the opportunity to work with federal labs to develop her company's technology.

All six finalists will compete for the grand prize, a $1 million investment.

The bacteria produce granules of a plastic called PHA. It's extracted and processed into pellets that can be sold and turned into plastic products. (Craig Chivers/CBC)

Genecis's lab is a space worthy of a scrappy startup, with yellow paint peeling from its walls and antique-looking wooden lab benches. (The company says the University of Toronto has been very supportive, charging just $300 a month in a neighbourhood where bachelor apartments go for $1,500 or more).

It smells like a washroom that needs cleaning, from a combination of food waste and bacteria.

"It's completely harmless to humans," Yu said of the smell. She admits neighbouring startups have complained, but things are better now that the company has upgraded its ventilation systems.

"Sometimes we give them chocolates as a sort of thank you for dealing with our smell."

It's most pungent in the room where staff don protective yellow coats and grind the food waste into a slurry that can be filtered into a liquid thin enough for bacteria to sip from.

There's one tank of bacteria that predigest the food waste into bite-sized molecules. Those molecules get run through another filter and are fed to "PHA" bacteria in another cylindrical glass tank. They spend four to 24 hours fattening themselves up before they're removed from the bioreactor tank and the PHA is extracted with chemicals such as bleach.

A home for the new plastic

Once the company is making PHA on a large enough scale, the material will be incorporated into compostable resins made by by Competitive Green Technologies, based in Leamington, Ont.

The company makes compostable straws that contain PHAs that it imports from overseas, along with other compostable resins that don't yet contain PHAs.

A few months ago, company CEO Atul Bali was contacted by Yu, who wondered if he would be interested in collaborating.

Bali, who said his company's objective is to reduce dependance on fossil fuels and be more environmentally friendly, is keen about the idea of a Canadian supplier.

"I'm pretty excited about what Genecis is doing," said Bali, who says the two companies have similar values. "We believe … there's no such thing as waste. Waste is a product looking for an opportunity."

He said he's also keen to help move Canadian biotechnology forward by finding a home for Genecis's plastic as soon as it's in production.

So far, he has provided Genecis with the standards the PHA needs to meet in order to be compatible with his resin for straws. He figures the company is about a year away from being able to provide it.

In the future, he said the PHAs may be incorporated into some of the company's other resins, including one used in compostable coffee pods made by Club Coffee for brands such as McDonald's and President's Choice. That resin, developed in collaboration with the University of Guelph, currently contains a combination of coffee bean skins, bioplastics and compostable petroleum-derived plastics.

Not accepted for municipal composting

There are still other challenges.

A big one is that compostable plastics — including coffee pods already on the market — aren't accepted in municipal organic waste diversion programs in Canada, although some are going through tests in places like Toronto.

PHA is already one of the plastics in McDonald's and President's Choice compostable coffee pods. It's sourced overseas, but PHA from Genecis's could soon be incorporated. (University of Guelph)

Most plastics aren't compostable, and most of what ends up in the green bin is "contamination" — so plastics are typically screened out by machines.

That's the case in Moncton, N.B., where waste diversion co-ordinator Gena Alderson said compostable plastics would be difficult to recover in the local composting plant.

Still, she thinks compostable options are better than recyclable for things like coffee pods as they're more likely to break down even if they don't make it to a composting facility.

But reusable options are always better, she added.

"I think the best thing is to avoid single use whenever we can."

Corrections

  • An earlier version of this story incorrectly stated that Competitive Green Technologies' resin for compostable coffee pods contains PHA plastic. In fact, its compostable resin for plastic straws contains PHA plastic, but not its compostable coffee pod resin, although it may in the future. Also, while the coffee pod resin contains a compostable plastic polymer material derived from petroleum, Atul Bali notes that in the industry this is technically called a "compostable substance from petroleum" rather than a plastic.
    Oct 29, 2018 1:19 PM ET

About the Author

Emily Chung

Science and Technology Writer

Emily Chung covers science and technology for CBC News. She has previously worked as a digital journalist for CBC Ottawa and as an occasional producer at CBC's Quirks & Quarks. She has a PhD in chemistry.