French inventors convert food waste into biodegradable plastic

Three friends who met at university in Bordeaux have invented a process where organic waste from canteens is turned into a biodegradable plastic.

After two-and-a-half years of research, their company, Dionymer, has progressed from producing a few grams of plastic a month to a kilogram.

They have just raised €2.5million to build a larger unit which will produce 100kg of the plastic, called polyhydroxyalkanoates (PHA), by 2025.

“We will then upscale, and plan to have a large factory or factories able to produce 1,000 tonnes a year in five years,” the firm’s CEO, Thomas Hennebel, told The Connexion.

“The plastic can be used in cosmetics, or made into sheets for packaging or for uses like geo-textiles, such as the plastic used to heat the ground for melons. It can even be spun into fibres similar to polyester. 

“Once it has been used, it can be composted, even in a household composter, and does not leave any microplastics. If it is not composted and ends up in the ground or sea, it also biodegrades without leaving a toxic trace or microplastics.”

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'Taking the idea out the lab'

Mr Hennebel and co-founders Antoine Brege and Guillaume Charbonnier were at university in Bordeaux together. They studied chemical engineering and soon became friends.

After graduating, Mr Hennebel worked for a large company as an engineer, before moving into management and consulting. Mr Charbonier worked as a technical engineer for a number of medium-sized firms, while Mr Brege remained at university to pursue a doctorate.

“We stayed in touch, and five years later were discussing our experiences and advances in chemistry and decided there was potential to take the techniques being developed out of the laboratory and to try to make plastic this way,” said Mr Hennebel.

“Like everyone else, we are aware of the problems of plastics in the ocean and in the ground and this is a way of providing an alternative to everlasting fossil oil-based plastics.” 

Bio-sourced plastics

For cosmetics, where plastics are often used in products such as hair conditioners or fillers, the price of the bio-sourced PHA plastic will be close to fossil oil-based offerings.

For other uses, such as geo-textiles, it is likely to be a bit more expensive, but manufacturers should be able to make up the difference from tax breaks for using fewer fossil fuel-based products.

At the moment the company is growing in Bordeaux, where it has an agreement to receive bio-waste, mainly from school and hospital kitchens, from the urban waste-collecting authority.

Bordeaux is also of interest because of the amount of grape skins left over from winemaking, which can be used as well.

The waste is placed in tanks and fermented with a bacteria. This produces a liquid which can then be treated to extract the plastic, in the form of a white powder, ready to be melted at plastic manufacturers.

At the end of the process a brown “cake” is left, which is sent to methane plants for a further fermentation to produce natural gas.

Processes using similar treatment plants are being set up by rival companies in the United States and Asia, but they are concentrating on agricultural waste products, such as straw, rather than domestic waste.

Read more: Is everyone in France affected by new obligatory home waste rules?

Mr Hennebel said recent legislation in France making it compulsory for people to sort their domestic waste helped confirm they were on the right path.

“It is unlikely that we will be able to move away entirely from plastics, so it is important that alternatives to fossil oil-based plastics are found.

“Our system works and soon there will be no excuse to use polluting plastics where bio-sourced ones work as well.”