Life cycle assessment of agave bagasse management strategies: PLA biocomposites versus conventional waste disposal practices

Abstract

Tequila production is one of Mexico's largest agro-industries, generating significant amounts of agave bagasse (AB) as its primary solid waste. Current AB management practices encompass composting, open dumps, and incineration. Life cycle analysis was developed to compare the environmental impact of these management scenarios with developing value-added agave fiber (AF) reinforced plastic biocomposites and generating biogas through anaerobic digestion. The assessment compares three molding methods for the PLA-AF biocomposite, with the environmental impact evaluated against pure PLA and low-density polyethylene (LDPE). Extrusion-injection molding was the most environmentally friendly molding method across all indicators, primarily due to the reduced inputs required for pretreating the fibers. Among the current management scenarios, composting was the least environmentally impactful for the global warming potential indicator. Nonetheless, composting requires substantial time and land use, posing challenges for some producers. Incineration displayed a significant trade-off on the fossil resource scarcity indicator by replacing natural gas. Anaerobic digestion displayed high impacts in all indicators as AB does not yield high methane potential. While the production of PLA-AF displays a significantly higher environmental impact, it remains a preferable option when compared to pure PLA and may further improve its sustainability through green chemistry principles. Notably, LDPE was less environmentally impactful than both bioplastic options assessed, due to the environmental impacts of PLA production and the widespread standardization of LDPE production processes. Context-specificity is critical to assess the environmental impact of circular bioeconomy pathways, which are not always inherently beneficial, while addressing SDG 12: Responsible Consumption and Production.