Not only are PHAs derived from renewable sources, but they are also compostable, biocompatible, and fully biodegradable – in soil and water.
Given this array of end-of-life options, recycling PHA might not be the first option in the agenda. Not, however, for a research team at the University of Birmingham in the UK, which is working towards creating a circular economy for bioplastics by exploring the potential to depolymerise PHA at the end of its life.
The project ‘Recycling PHA for Second life’ (RePHASe) studies hydrolysis as a PHA depolymerisation technology. The scientists are investigating whether the process, which has been proved in small batch quantities, can be scaled up using a continuous set up where water and catalysts are preserved and recycled into the process.
The team will use design software to map out the full chemical process, the heating and total energy demand, as well as a full design of the process to demonstrate the industrial scale. They will determine if its technically feasible and economically viable to scale up the process through a Life Cycle Analysis (LCA) and techno-economic assessment (TEA).
Two undergraduate researchers already did a case study with P3HB, one of the most common types of PHA. Their project found that soaking the polymer in methanol for 12-16 hours, and subsequently letting it dry, halved depolymerisation time, which is likely to lower resource expenditure.
Going forward, the team at RePHASe hopes to receive funding to investigate the engineering requirements to expand the process to commercial scale.