Dr Kevin O’Connor
Dr. Kevin O’Connor and his research team from the School of Biomolecular & Biomedical Sciences, and the Centre for Synthesis and Chemical Biology have come up with a way to recycle old plastic bottles and polystyrene containers with microorganisms. The process is known as upcycling- a step beyond recycling.
A combination of chemistry and microbes can transform the non-environmentally friendly polystyrene foam into something quite the opposite, and this has been made possible through the discovery that specific strains of Pseudomonas bacteria have the ability to turn ordinary PET plastics into a biodegradable plastic called PHA. To put it at its simplest – the chemists melt the plastic; the bugs eat it, and convert it into another plastic that is biodegradable.
But not only is it biodegradable; the resulting plastic is also much stronger, and can be used in numerous medical applications such as artery-supporting tubes. It only becomes brittle at minus 43.3 degrees Celsius, so it’s freezer safe. While you can also heat it to 278 Celsius, it will degrade in a compost heat at 32 degrees because the microorganisms (in the landfill) release enzymes.
The process works as follows- Polypropylene (plastic) is cooked until it turns into a styrene oil. The oil is then fed to microorganisms, which metabolically turn it into globules of fatty acids and stores it in the form of a plastic called PHA. When 60 percent of the bacteria consist of those fatty acids, the microorganism is split open and the harvested fatty acids are converted to a biodegradable plastic. The exceptional thing about PHA is that it is a flexible heat resistant plastic that, unlike polystyrene, is biodegradable. Hence, it can go safely into landfill and disappear over time.
The next step is to improve the PHA-producing efficiency of the process, says O'Connor. "A quarter to a third of each cell is filled with plastic – we want to increase that to 50 to 60%." In the future, this could lead to more PHA products, something that hasn't been possible up until now due to the lack of a way to produce PHA in mass quantities.
Currently, there are two methods for dealing with waste plastic. In Ireland, we recycle it and ship it to other countries. But plastic bottles have a low recycling value, so, a lot of the plastic ends up in landfills forever. The other method is to burn it, a practice followed in Sweden, Switzerland and Germany. While this yields useable energy, it’s not the cleanest practice in the world.
If O’Connor’s process can be brought up to an industrial level, it could help the world get rid of its mass of waste plastic. The group has made several patent applications and next year, there are plans to move the process out of the lab and do a multi-kilogram recycling centre with a large waste company.
