Torrefaction of fish waste (Sardinella fimbriata) in a fixed bed reactor: Yields and biochar characterization

Abstract

Torrefaction is a promising process to upgrade biomass and produce solid biofuel. In this study, the fish by-product (Sardinella fimbriata), a fish-processing waste from the food industry highly prevalent in the east coast region of Peninsular Malaysia was investigated in a fixed bed torrefaction reactor with varying reaction temperature (200, 250, and 300°C) under a nitrogen atmosphere and single residence time (30 minutes). The distribution and yield of the biochar, bio-oil, and biogas were examined, and further characterization of the biochar was performed (proximate and ultimate, SEM, and FTIR analysis). The results indicated that with the increased torrefaction temperature, solid char yield decreases down to ∼ 52 % while bio-oil and biogas fluctuate between 7 - 28 % and 21 – 27 &, respectively. The proximate and ultimate analysis of the torrefied solid char showed that the fixed carbon, carbon content increased while volatile matter, moisture, hydrogen, and oxygen content decreased with temperature rise. From the SEM analysis, the torrefaction temperature causes an increase in biochar porosity. Lastly, from the FTIR analysis, it can be seen that there are degradation and formation of certain functional groups such as O-H, C-H, C=C, C=O, C-O, and C-C with torrefaction temperature variations.