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.

This CDT will deliver impact aligned to the following agendas:

People
A2P will provide over 60 PhD graduates with the skill sets required to deliver innovative sustainable products and processes into the UK chemicals manufacturing industry. A2P will inspire and develop leaders who will:
- understand the needs of industrial end-users;
- embed sustainability across a range of sectors; and
- catalyse the transition to a more productive and resilient UK economy.

Economy
A2P will promote a step change towards a circular economy that embraces resilience and efficiency in terms of atoms and energy. The benefits of adopting more sustainable design principles and smarter production are clear. For example, the global production of active pharmaceutical ingredients (APIs) has been estimated at 65,000-100,000 tonnes per annum. The scale of associated waste is > 10 million tonnes per annum with a disposal cost of more than £15 billion. Consequently, even a modest efficiency increase by applying new, more sustainable chemical processes would deliver substantial economic savings and environmental wins. A2P will seek and deliver systematic gains across all sectors of the chemicals manufacturing industry. Our goals of providing cross-scale training in chemical sciences with economic and life- cycle awareness will drive uptake of sustainable best practice in UK industry, leading to improved economic competitiveness.

Knowledge
This CDT will deliver significant new knowledge in the development of more sustainable processes and products. It will integrate the philosophy of sustainability with catalysis, synthetic methodology, process engineering, and scale-up. Critical concepts such as energy/resource efficiency, life cycle analysis, recycling, and sustainability metrics will become seamlessly joined to what is considered a 'normal' approach to new molecular products. This knowledge and experience will be shared through publications, conferences and other engagement activities. A2P partners will provide efficient routes to market ensuring the efficient translation and transferal of new technologies is realised, ensuring impact is achieved.

Society
The chemistry-using industries manufacture a rich portfolio of products that are critical in maintaining a high quality of life in the UK. A2P will provide highly trained people and new knowledge to develop smarter, better products, whilst increasing the efficiency and sustainability of chemicals manufacture.
To amplify the impacts of our CDT, effective public engagement and technology transfer will become crucially important. As a general comment, 'sustainability' styled research is often regarded in a positive light by society, however, the science that underpins its effective implementation is often poorly appreciated. The University of Nottingham has developed an effective communication portfolio (with dedicated outreach staff) to tackle this issue. In addition to more traditional routes of scientific communication and dissemination, A2P will develop a portfolio of engagement and outreach activities including blogs, webpages, public outreach events, and contribution of material to our award-winning YouTube channel, www.periodicvideos.com.

A2P will build on our successful Sustainable Chemicals and Processes Industry Forum (SCIF), which will provide entry to networks with a wide range of chemical science end-users (spanning multinationals through to speciality SMEs), policy makers and regulators. We will share new scientific developments and best practice with leaders in these areas, to help realise the full impact of our CDT. Annual showcase events will provide a forum where knowledge may be disseminated to partners, we will broaden these events to include participants from thematically linked CDTs from across the UK, we will build on our track record of delivering hi-impact inter-CDT events with complementary centres hosted by the Universities of Bath and Bristol.