Researchers in Germany recently published a research paper in Frontiers in Microbiology in which they describe the isolating a strain of bacteria that can degrade plastic. The specific bacteria Pseudomonas sp. were able to biodegrade polyurethanes. The plastic, specifically polyurethane, served as the sole source of carbon and energy for the bacteria.
Due to the variety in physical, chemical, thermal and mechanical properties, polyurethanes (PU)have a broad range of applications, Some of the main applications are detailed below:
• Flexible PUF: automobile seating, furniture, carpets.
• Rigid PUF: refrigerator, insulation board.
• Elastomers: footwear, adhesives, medical.
• RIM: automobiles (bumpers, side panels).
• Other: carpets, casting, sealants.
As PUs are used in so many every day applications and industrial uses, they enter the municipal solid waste stream, usually by way of discarded consumer and industrial products. These products frequently are durable goods with a long lifespan such as upholstered furniture, mattresses and automobile parts. By weight, approximately 1.3 million tons of waste PUs are generated each year in the USA alone. The largest market is for PUF (47% flexible and 28% rigid), followed by PU elastomers (8%). North America represents around 30–35% of the world total consumption, with the remainder in Western Europe (around 40%), the Far East (around 15%) and the rest of the world (around 10–15%).
Polyurethanes, due to there diverse chemical composition, are very difficult to recycle. Due to their high flammability, they are typically treated with flame retardants that may be carcinogenic.
“The bacteria can use these compounds as a sole source of carbon, nitrogen and energy,” says microbiologist Hermann Heipieper, from the Helmholtz Centre for Environmental Research-UFZ in Germany. “This finding represents an important step in being able to reuse hard-to-recycle PU products.”
The discovery was made in the soil underneath a waste site containing an abundance of brittle plastics. Having spotted the strain, the scientists ran a genomic analysis and other experiments to work out the bacterium’s capabilities. It will be some time before there is a commercial-scale bacteria-based solution to plastic waste challenge.
In Canada, researchers from the University of British Columbia and industry partner Polymer Research Technologies are working together to develop technology that will allow polyurethane foam waste to be chemically recycled into polyols. If successful, the research will lead to a commercial-scale process that can produce a reusable, recyclable, economical, and eco-friendly raw material alternative to petroleum-based virgin polyol.