Environmental evaluation of distributed versus centralized plastic waste recycling: Integrating life cycle assessment and agent-based modeling

Plastic waste is internationally recognized as a problem, fueled by increased public awareness of environmental concerns and the steady increase in waste import bans. Modern sorting and recycling technologies are mature, but face implementation limitations in highly dense urbanized regions such as Singapore due to significant space constraints and expensive labor. Distributed plastic sorting and recycling facilities at small-scale closer to points of plastic waste generation offer the possibility of increasing the recovery of plastic waste streams in urbanized settings. To quantify the environmental performance of such systems, this study compares the life cycle greenhouse gas emissions of large-scale centralized facilities versus distributed small-scale facilities for sorting and recycling plastic bottles and takeaway containers generated in the central region of Singapore. An agent-based model is used to simulate different scenarios of plastic waste generation, collection routes, sorting, and recycling. The simulation results are used in a multi-level life cycle assessment to quantify the greenhouse gas emissions of the plastic sorting and recycling network as well as its individual entities. The results reveal that the life cycle greenhouse gas emissions of small-scale distributed plastic recycling compared to large-scale centralized systems are sensitive to the transport distance traveled and the type of trucks used.