New process turns food waste into biodegradable plastic

Food production and packaging have two major problems: the mountains of food wasted around the world, equivalent to a third of all produce; and the growing problem of plastic pollution from packaging. What if both issues could be tackled with a common solution?

That is what a team of researchers at Binghamton University in New York State aim to do with a new process, which turns food waste into a type of biodegradable plastic.

“At Binghamton, the dining halls give wasted food to farmers to feed their livestock. I thought maybe we could try to directly convert that food waste into biodegradable plastics. There was little information from research publications about the feasibility of this idea, so we felt like maybe that was the gap we could work on,” said Professor Sha Jin, part of the research team.

Biodegradable plastic production can be expensive because it relies on refined sugar substrates and pure cultures of microorganisms, the researchers said. As part of the work, the Binghamton team fed Cupriavidus necator bacteria with lactic acid fermented from food waste and additional ammonium sulfate.

The bacteria synthesised polyhydroxyalkanoate (PHA) plastic as a way of storing carbon and energy. About 90% of the PHA could be harvested and shaped into biodegradable packaging and other products.

The food waste could reportedly be stored for a week without any adverse effects to the bioconversion process, offering flexibility for collection at an industrial scale. The team also determined whether the bioconversion depended on any specific food type, and how to deal with the different kinds of waste that a collection centre would receive.

“We discovered that the process is very robust, as long as we have different types of food mixed in at the same ratio,” Professor Jin said. “We control the temperature and the pH during fermentation, and those conditions encourage organic acid-producing bacteria to grow.”

Next, the team plans to use the solid residue left over from the fermenting process as an organic fertiliser. They also aim to scale up the process, to ensure it performs as expected.

The work, which was led by Tianzheng Liu, was reported in Bioresource Technology.

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