(650d) Multi-Scale Life Cycle Environmental Impacts of Urban Waste Valorization

Valorizing urban waste is a promising direction for a circular economy and reducing environmental impacts related to the waste management industry. Various biomass valorization pathways are available, such as converting wastes to biofuels, chemicals, biochar, and other bio-based products¹. Understanding the potential environmental benefits/risks of each pathway at different scales (e.g., product, process, and regional scales) is critical to support the decision making related to engineering, supply chain, and policy design.

This topic will present a framework that integrates process-level life cycle assessment (LCA)^{2, 3} with geospatial analysis to quantify the large-scale environmental impacts of urban waste utilization. A case study of converting urban tree wastes into different products will be presented. Specifically, the case study explores compost, lumber, and biochar (produced by pyrolysis). Different pathways are compared with counterfactual scenarios (e.g., landfilling) to understand the net environmental benefits of valorizing urban tree wastes. The geospatial analysis was conducted to quantify the environmental impact reduction of tree waste utilization in different regions and to identify the main contributors to such reductions.

The results show significant geospatial variations of the environmental benefits associated with different valorization pathways, which can be explained by the availability and types of urban tree wastes. Compared to landfilling and incineration, the environmental benefits regarding climate impact and eutrophication of different valorization pathways will be presented.

(1) Banerjee, S., and Arora, A. (2021) Sustainable bioprocess technologies for urban waste valorization, Case Studies in Chemical and Environmental Engineering 4, 100166.

(2) Lan, K., Kelley, S. S., Nepal, P., and Yao, Y. (2020) Dynamic life cycle carbon and energy analysis for cross-laminated timber in the Southeastern United States, Environ. Res. Lett. 15, 124036

(3) Lan, K., Ou, L., Park, S., Kelley, S. S., Nepal, P., Kwon, H., Cai, H., and Yao, Y. (2021) Dynamic life-cycle carbon analysis for fast pyrolysis biofuel produced from pine residues: implications of carbon temporal effects, Biotechnology for Biofuels 14, 191.