Outline of a Process for the Hydrothermal Liquefaction of a Tannery Sludge for Biofuel Production

The growing interest in renewable energies due to climate change concerns is triggering research towards liquid fuels production from renewable energy resources. The civil/industrial sludge conversion into bio-crude via hydrothermal liquefaction (HTL) can simultaneously provide a replacement to non-renewable crude-oil while dealing with waste disposal issues. In this work, a tannery sludge has been characterised by several techniques to preliminary assess the sludge composition and properties. Moreover, a lab-scale plant consisting in a batch autoclave was designed, whose exercise can allow to elucidate the reaction pathways of the HTL process so to identify optimal operating conditions for obtaining a high-yield bio-crude with more attractive energy properties. Finally, to investigate the relationships between HTL operating conditions and yield/quality of the sludge-derived bio-fuels, an original elaboration of literature data was offered.