A convenient method to determine recycling boundary for low-value materials in household waste: A case study of compostable food waste in Taichung City

Abstract

Abstract Sustainable material management and circular economy are worldwide trends for solid waste management. However, issues related to the management of low-value materials (LVMs) left in household waste may pose challenges in successfully adopting such a concept. The major cost to recycle LVMs are affected by recycling boundaries and treatment capacity, where spatial densities of LVMs generation and product consumption are lurking but decisive. In this study, convenient equations have been developed aiming to assist municipalities in sustainable LVMs management via determining the optimized recycling boundary with minimal average total unit cost, including transportation, treatment, and economy of scale. The developed convenient equations reveal that higher spatial density, higher unit transportation cost, and lower treatment cost tend to have smaller optimal recycling boundaries. A case study of regular LVM, i.e., compostable food waste (CFW) in Taichung City was done to verify the flexibility and applicability of these equations. These equations provided information to determine appropriate recycling schemes, including the interactions among recycling radius, the minimal unit total cost, and recycling rate. The results of the equations fitted actual data in both unit total cost and recycling boundary of cost-efficiency. Spatial density of recycled LVMs, treatment cost, and transportation cost were found to affect unit total cost in descending order, respectively. Once the recycling rate of CFW increases, the expected unit total cost would be half of the current cost and is expected to further reduce. The convenient equations were capable to provide information on the appropriate recycling boundary of the plant with cost efficiency in consideration to the given recycling goal of municipalities.