Biological recycling of polyethylene towards high value products

This project aims to address the plastic waste problem. Plastic is a very valuable and useful material due to its wide variety of properties. However, its durability has led to an increasing disposal challenge. Current routes are limited to landfill, energy recovery via incineration and mechanical recycling. Mechanical recycling is a finite process, the polymer remains chemically unchanged, and the plastic undergoes physical stress. This process diminishes its physical properties and results in the recycled material eventually being landfilled. There is also a large proportion of plastic waste which is unaccounted for and inevitably pollutes the natural environment. This problem is exasperated by a continued rise in plastic production. This research will offer an alternative route for plastic waste by developing a successful biological recycling technology for plastic and by helping plastic become a more circular material. Biological recycling utilises microorganisms and enzymes to degrade plastic and is heavily dependent on the type of plastic. This technology enables the chemical components of the plastic to be liberated and repurposed, with the potential of being sustainably sourced high value products. Many companies and the government have recognised the harmful effects of petrochemically sourced compounds, the finite resource that is crude oil and their contribution to climate change. Therefore, many stakeholders are interested in green chemicals in order to increase the sustainability of their chemical processes.


This project will focus on a novel biological recycling route for plastic waste, specifically polyethylene (PE). The biodegradation process of PE uses a microorganism isolated from the environment, which is proven to degrade plastic. The decision to focus on PE was due to a number of factors, such as the significant contribution (~26%) PE makes to the global plastic market. Therefore, the potential environmental and societal impact of a successful sustainable recycling process for PE could be significant. PE is a polyolefin, and it has a strong carbon backbone structure. There is a lot of scope for polyolefin biodegradation as there are few microorganisms or enzymes with the ability to attack and cleave the strong carbon-carbon bonds. Therefore, the type of enzyme(s) and the mechanism will be very important. This project aims to initially gain a better understanding of the biodegradation process, as this is required before specific valuable products can be targeted for valorisation. This will involve exploring the biodegradation process in more detail, such as the metabolic pathways within the microorganism and the enzyme(s) responsible for biodegradation. This will then allow the process to be manipulated, while valuable products derived from the process using plastic waste feedstock can be investigated. This project is sponsored by Johnson Matthey.