Life cycle assessment of kerbside waste material for an open-looped and closed-loop production– towards circular economy designs

Abstract

Urbanization growth has increased the generation of municipal solid waste (MSW) and has the potential for recycling and reuse. However, it is frequently limited to a linear lifecycle mode which end up in landfills. A novel attributional lifecycle inventory model for lifecycle assessment based on value retention process (VRP) model of circular economy was developed to quantify the lifecycle inventory and measure the environmental impacts of multiple lifecycle stages, from in-community separation to the end-of-use/life stage and subsequent lifecycles. This investigation focused on assessing the environmental impacts of two distinct in-community waste glass separation methods - separate kerbside glass recycling bin (SKGRB) and mixed kerbside recycling bin (MKRB) - in combination with two recycling approaches - open-loop (asphalt) and closed-loop (glass container). The goal of the study was to make a comparative evaluation of the environmental impacts of these methods. Results showed that the SKGRB method had better environmental performance (40–60% reduction compared to the MKRB method) for both materials. Closed-loop recycling of glass container production had higher environmental impacts due to higher energy consumption in production in one lifecycle, while the open-loop recycling method of asphalt had higher environmental impacts despite fewer circulations, due to higher production volume in 21 years. The results of the sensitivity/uncertainty analysis showed that environmental impacts decreased as the allocation coefficient decreased, reaching stability when the coefficient reached the waste materials percentage in the new product's mixed design.