Optimization of an integrated solid waste management system based on greenhouse gas emissions taking into consideration materials flow due to product reus

Product reuse contributes favorably to waste management and resource recovery by diverting products from terminal disposal to second-hand markets. Activities that promote the process of reuse make valuable products available to second-hand customers, contribute to waste prevention, and help mitigate the adverse impact of solid waste management on the environment. To quantify the contributions of product reuse to waste prevention and the evaluation of its contributions to the alleviation of adverse effects on the environment required three fundamental developmental steps, which can be summarized as follows: (a) the development of a methodological framework to allow the quantitative analysis of second-hand products flowing through the economy. The novel methodology standardizes record keeping and characterizes commonly reused post-consumer products by assessing the outgoing product flow from reuse enterprises. The approach groups material composition of individual products into primary product categories, creating a simplified method to characterize products, (b) the study of the flow of second-hand products required the assessment of the disposal habits and acquisition practices of adults for second-hand products. Three separate surveys were conducted for three commonly reused products (books, clothing and furniture) using the Amazon Mechanical Turk online platform. Associations were observed between disposal and acquisition methods of used products and demographics, such as age, gender and education level. The existence of preferred disposal routes and acquisition channels of second-hand products allows the recovery of reusable products in a more efficient manner by combining efforts in initiatives that can impact disposal and acquisition of goods. And (c) finally, the development of an optimization model to minimize the greenhouse gas emissions of an integrated solid waste management system that includes reuse strategies and practices such as reuse enterprises, online platforms, and materials exchanges along with traditional solid waste management practices such as recycling, landfilling, and incineration. Using material flow analysis in combination with life-cycle assessment, the optimization model, identified hereafter as Fortuna ISWM (Integrated Solid Waste Management) optimization model, provides the best outcome regarding greenhouse gas emissions by redistributing product flows in the integrated solid waste management system to the least impacting routes and processes. The optimization model provides a basis for understanding the contributions of reuse to the environmental benefits of the integrated solid waste management system and the exploration of effects of the reuse sector on waste prevention.