Improving the Anaerobic Digestion of Wine-Industry Liquid Wastes: Treatment by Electro-Oxidation and Use of Biochar as an Additive

Wine lees have a great potential to obtain clean energy in the form of biogas through anaerobic digestion due to their high organic load. However, wine lees are a complex substrate and may likely give rise to instabilities leading to failure of the biological process. This work analysed the digestion of wine lees using two dierent approaches. First, electro-oxidation was applied as pre-treatment using boron-doped diamond-based electrodes. The voltage was 25 V and dierent treatment times were tested (ranging from 0.08 to 1.5 h) at 25 C. Anaerobic digestion of wine lees was evaluated in batch tests to investigate the eect of electro-oxidation on biogas yield. Electro-oxidation exhibited a significant positive eect on biogas production increasing its value up to 330 L kg1 of volatile solids after 1.5 h of treatment, compared to 180 L kg1 of volatile solids measured from raw wine lees. As a second approach, the addition of biochar to the anaerobic digestion of wine lees was investigated; in the experimental conditions considered in the present study, the addition of biochar did not show any positive eect on anaerobic digestion performance.