Physicochemical characterization and energy recovery of spent coffee grounds

Abstract

This paper tackles the physicochemical characterization of spent coffee grounds resulting from a blend of six types of coffee (Arabica and Robusta) used in different proportions in a professional DeLonghi coffee machine. Information was collected on their particle size distribution, morphological characteristics, composition and energy value. Since it is impossible to make pellets and briquettes out of pure spent coffee grounds that would meet sustainability standards, our paper suggests another use for coffee grounds as firelighters. Several firelighters containing agricultural waste, additives and 100% Arabica spent coffee grounds have been designed and manufactured. The firelighters thus obtained were first analyzed by microscale combustion calorimetry (MCC), a standard test method used to determine the flammability characteristics of materials. The firelighters obtained have high values of heat release capacity, and of the total flow of heat released, as well. The firelight containing coffee grounds also has a lower percentage of residue and a longer duration of the combustion process, which are important aspects considering the practical applications concerned.

Keywords

• Spent coffee grounds
• Particle size distribution
• Morphological characteristics
• Composition and energy value
• TG/MS/FTIR analysis
• Firelighters