Comparing the environmental performance of distributed versus centralized plastic recycling systems: Applying hybrid simulation modeling to life cycle assessment

The plastic waste dilemma has gained international attention because of increased public awareness and the rise of waste import bans. Sorting and recycling technologies that deal with plastic waste streams exist but face challenges in highly dense urbanized regions such as Singapore because of high space requirements. Multiple small-scale plastic sorting and recycling facilities that are distributed closer to points of waste generation offer the possibility of increasing the recovery of plastic-waste streams in urbanized settings. To holistically quantify the environmental performance of this type of system, a life cycle assessment (LCA) is conducted to compare five different scenarios of distributed and centralized sorting and recycling of plastic bottles and takeaway containers in Singapore. A hybrid simulation model is used to simulate the complex dynamics of waste-processing systems which involves waste generation, collection scheduling, sorting, recycling, and disposal of residual materials. The results of the LCA showed that the life cycle environmental impacts to climate change, water depletion, and terrestrial ecotoxicity of the distributed scenarios were higher than the centralized scenarios by 7-30% depending on the impact category. Although the distributed scenarios had lower total travel distances, their reliance on commercial vans led to their higher environmental impacts than the centralized scenarios. The findings of this study provide motivation for future research in applying hybrid simulation models in LCAs of waste-to-resource exchange networks. The data used to carry out the hybrid simulations and the LCA are provided as Supporting Information. This article met the requirements for a Gold-Silver JIE data openness badge described at http://jie.click/badges.