Study suggests that mechanical recycling is most environmentally-friendly method of closed-loop polymer recycling
According to the study, over 400 million metric tons of plastic waste are generated across the world each year, an outcome that pollutes the environment and drains resources. As such, it compares the mechanical recycling and solvent-based dissolution of high- and low-density polyethylene, polypropylene, and PET, alongside glycolysis, vapour methanolysis, and enzymatic hydrolysis in relation to PET, based on their environmental performance. This research is hoped to serve as a ‘quantitative and transparent’ data set of material quality, material retention, circularity, contamination tolerance, minimum selling price, greenhouse gas emissions, energy use, land use, toxicity, waste generation, and water use metrics for closed-loop polymer recycling technologies, which can them be used to compare emerging recycling solutions as they develop. The results state that mechanical recycling and PET glycolysis result in the best economic and environmental performances, with respective decreases of 9%-73% and 7%-88% when compared to competing technologies. Meanwhile, the highest-quality recyclate materials are said to come from dissolution, enzymatic hydrolysis, and methanolysis, which are said to raise the quality of standard recyclates by 2%-27%.