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

Pyrolysis is an attractive method to produce biochar from bio-renewable waste materials. In order to optimize the yield and control over the process, it is necessary to understand the interactions between the two compositions. This study investigated the primary reactions and synergistic effects of the pyrolysis process involving two food wastes: brewery spent grains (BSGs) and coffee ground waste (CGW). Pyrolysis of BSG, CGW and their mixtures has been examined utilizing thermogravimetric/differential thermogravimetric analysis. The characteristics of the generated biochar were assessed utilizing several analytical instruments. Although the mass yields of biochar were only slightly different when the feedstocks were blended, the N- and C-conversion efficiencies were higher for the blends than for either of the feedstocks alone. As a result, the biochars from the blends have a higher overall carbon content, fixed carbon content and lower oxygen content than those from the pure feedstock. Fourier transform infrared and pyrolysis gas chromatography/flame ionization detector results identified the main functional groups and determined the yield of the products from each blend. Furthermore, scanning electron microscopy-energy dispersive spectrometry was used to explore the surface morphology and composition of biochars produced by the co-pyrolysis process. The overall findings offered here are a basic investigation of the co-pyrolysis of food wastes and potential applications of the produced solid products for environmental and energy-conversion purposes.