Pyrolysis of grape marc before and after the recovery of polyphenol fraction

In this work, winery industry wastes were valorised through the extraction of high added value compounds (polyphenols), followed by thermal conversion of the exhausted solid residues. For this purpose, three different temperatures (623, 723 and 823 K) were tested. The increase of the heat treatment temperature resulted in a significant increment in gas production containing methane and other hydrocarbons. Lipophilic liquid product quantity in grape marc was limited both before and after the polyphenol extraction. The recovery of phenolic compounds before the thermal treatment notably decreases the chemical oxygen demand level of the resulting hydrophilic liquid fraction. The pyrolysis residue represents from 30 to 55% of the initial mass but corresponds to a relevant decrease of its volume, and can be considered a good source of graphitic carbon with higher calorific value with respect to the initial grape waste and applicable for energy production.