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ARS Home » Northeast Area » Wyndmoor, Pennsylvania » Eastern Regional Research Center » Sustainable Biofuels and Co-products Research » Research » Publications at this Location » Publication #413040
Research Project: Chemical Conversion of Biomass into High Value Products

Location: Sustainable Biofuels and Co-products Research

Title: Pyrolysis of brewery spent grain, coffee ground waste and their blends

Author
item MAINALI, KALIDAS - Oak Ridge Institute For Science And Education (ORISE)
item Sarker, Majher
item Ellison, Candice
item Mullen, Charles

Submitted to: Journal of Environmental Management
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/10/2025
Publication Date: 7/11/2025
Citation: Mainali, K., Sarker, M.I., Ellison, C.R., Mullen, C.A. 2025. Pyrolysis of brewery spent grain, coffee ground waste and their blends. Journal of Environmental Management. https://doi.org/10.1177/0734242X251361876.
DOI: https://doi.org/10.1177/0734242X251361876

Interpretive Summary: In this study, two abundant food wastes, brewery spent grain (BSG) and coffee ground waste (CGW) were utilized separately and in combination to produce a value-added product, biochar. Co-carbonization via the pyrolysis process was employed for this transformation and the chemical and physical properties of the bio-char were analyzed. Results showed that there were benefits to processing the wastes together compared with separate treatment. For example, a higher level of carbon was retained in the products at certain blend rates, which is due to how the two feeds interacted chemically at high temperatures. These chars have the potential to be used in energy conversion and environmental applications. These findings offer a pathway for proper waste management of leftover grains from breweries and coffee grounds.

Technical Abstract: Co-carbonization is an attractive method to produce solid products (biochar) from biodegradable waste materials. To get better yield and control over the process, it is necessary to understand the interactions between the two compositions. This study explored the primary reactions and synergetic effects of the co-carbonization process of two food wastes, brewery spent grains (BSG) and coffee ground waste (CGW). The characterization of the produced biochar was also evaluated. The co-carbonization behaviors of BSG, CGW, and their blends were investigated by using the thermogravimetric/differential thermogravimetric analysis (TGA/DTG), Fourier Transform infrared spectroscopy (FTIR) and micro pyrolyzer connected with a gas chromatograph/flame ionization detector (Py-GC/FID). The results confirmed the synergetic effects during the carbonation process which resulted in increased char yield and N-C conversion efficiency. FTIR and Py-GC/FID results identified the main functional groups and determined the yield of the products from each blend. Furthermore, scanning electron microscopy-energy dispersive spectrometry (SEM-EDS) was used to explore the surface morphology and composition of biochars produced by the co-carbonization process. The overall findings offered here a basic investigation of co-carbonation from food wastes and potential applications of the produced solid products for environmental and energy-conversion purposes.