Assessing the environmental performance of vermicompost from spent coffee grounds based on a life cycle approach

Purpose: This study investigated the physicochemical properties of vermicompost from spent coffee grounds (SCG) and assessed its environmental performance using Life Cycle Assessment (LCA). Additionally, the environmental performance of vermicompost was compared to other waste treatment and utilization scenarios. Method: Two treatments of compost and vermicompost were produced from SCG and solid cow manure (SCM) with three replicates per treatment. Eudrillus eugeniae earthworms were used for vermicomposting. The physicochemical characteristics measured included pH, EC, TOM, TOC, TKN, TP, and TK. Statistical analysis was conducted using mean, SD, ANOVA, and Tukey’s test. The comparison of the environmental performance of vermicompost and alternative scenarios (compost from SCG and SCM, SCG as soil amendment, and SCG as waste) was assessed through LCA. Results: Compost and vermicompost contained higher macronutrient contents than SCG. The LCA results revealed that vermicompost produced from SCG and SCM had significant environmental benefits by reducing the reliance on mineral N fertilizers and fishmeal in animal feed production, a 116% reduction in GWP100 compared with disposing in a landfill. A scenario analysis highlighted that disposing of SCG in a landfill had the highest impact on GWP100, while the baseline scenario demonstrated the most notable environmental benefit. In contrast, the baseline scenario exhibited the highest impact on EP, primarily due to NH3 emissions resulting from organic fertilizers. This underscores the need for effective management practices to mitigate the contribution of NH3 to eutrophication. Conclusion: Vermicomposting showed significant potential in reducing organic waste, specifically SCG. According to LCA, it displayed a relatively low environmental impact across various impact categories, primarily due to the substitution of N fertilizers and fish meal. Highlights Vermicompost from SCG and SCM is considered a nutrient-rich fertilizer. Life cycle assessment results show that vermicompost from SCG and SCM can reduce greenhouse gas emissions by 116% compared with other waste treatment scenarios. Significant reduction of reliance on chemical fertilizers and fishmeal in animal feed, leads to a massive reduction in greenhouse gas emissions. Vermicompost can cause ammonia emissions linked to water pollution. Effective management practices are needed to minimize ammonia emissions and maximize the environmental benefits of this sustainable solution.