Plastic waste is a massive problem both globally and in the United States. Packaging materials, containers and other discarded items are filling up landfills and littering the environment at a pace so rapid that scientists estimate by 2050 the ocean will have more plastic by weight than fish. Meanwhile, only about 5% of used U.S. plastic is recycled.
New research published in Science, builds on the use of chemical oxidation to break down a variety of plastic types. The new technology uses oxygen and catalysts to break down plastics into smaller, biologically friendly chemical building blocks. Then, it uses a biologically engineered soil microbe capable of consuming and ‘funneling’ those building blocks into either a biopolymer or a component for advanced nylon production.
Today’s recycling technologies can only operate effectively if the plastic inputs are clean and separated by type. That’s because, recycling becomes expensive and nearly impossible, when polymer chemistries are mixed. The big news is that this technology has the potential for processing plastics that cannot currently be recycled at all because they contain multiple types of plastic.
The new research has resulted in a process that can convert mixed plastics to a single chemical product. In other words, it is a technology that recyclers could use without the task of separating the plastic by type. In tests, the researchers applied the process to a mix of three common plastics: polystyrene; low-density polyethylene; and high-density polyethylene. The oxidation process broke down the plastics into a mixture of three compounds which, in the absence of the engineered soil microbe, would require advanced and costly separation to yield pure products.
The researchers engineered the microbe to biologically funnel the mixture into one of two products: an emerging form of biodegradable bioplastics, and another product that can be used in the manufacture of performance-advantaged nylon. Testing this process on other common types of plastics including polypropylene and polyvinyl chloride will be the focus of upcoming work. Best of all, the chemical catalysis process used here is clean. It’s just a way of accelerating a process that occurs naturally. But instead of degrading over several hundred years, it breaks down these plastics in hours or minutes.