TOWARDS CIRCULAR WASTE MANAGEMENT IN UTRECHT UNIVERSITY - Investigating the potential for a decentralised, pyrolysis based, plastics waste management system on campus

Abstract

Utrecht University is committed to reducing their plastic waste production and as a starting point, banned plastic water bottles in the vending machines. Moving forward, Utrecht University wants to become zero waste in 2030. Can Utrecht University reduce its impact from plastic waste and become an example for decentralised, circular plastic waste management through pyrolysis? To answer this question this study was divided into three phases: Material Flow Analysis (MFA), Pyrolysis experiments and a Life Cycle Assessment (LCA). The MFA allowed to understand the composition of plastic waste on Utrecht Science Park and extrapolate this composition to the rest of the university. The pyrolysis experiments gave insight into the types of products which can be expected and their properties. Finally, the LCA summarised the environmental impacts on Climate Change, Cumulative Energy Demand and Freshwater Ecotoxicity. Plastic waste at the Utrecht Science Park mostly consists of PET bottles and food packaging (39.5% and 17.5% respectively). Around 12.3kg of clean plastics were estimated to be produced at the Ruppert, Bestuursgebouw, Educatorium and Library buildings. When extrapolating these results to a university-wide scale, 100kg of daily plastic waste can be pyrolyzed. From the pyrolysis stage, it was found that the pyrolysis gas produces enough heat to sustain the reaction at a pilot scale of 40kg per batch of plastic. The carbon content recovered in the pyrolysis products warrants a closure of loop so that the carbon is put back into the system by substituting naphtha for example. Moreover, the range of products which can be extracted range from light oils to waxes. The average impacts on a pilot scale were 0.75KgCO2-eq, -29MJ and 0.53PAF*m3*day for the three impact categories respectively. When comparing the decentralised pyrolysis system to a centralised system using mechanical recycling, it was found that the pyrolysis system has a 12% lower carbon footprint when the complete impacts of the cleaning stage was considered. Thus, proving the viability of such a decentralised pyrolysis system at Utrecht University.