Biomethane potential of wine lees from mesophilic anaerobic digestion

Wine lees (WL) are undervalued residues from the wine-making process. Anaerobic digestion (AD) of WL is highly challenging due to the acidic pH and high content of readily biodegradable compounds. This study investigated the biomethane potential (BMP) of 3 WL samples through mesophilic batch tests fed with 2–3 % total solids. The influence of wood-based biochar (BC), considering 2 different BCs and doses (3 and 10 g L−1), was also assessed. BMP values up to 1.257 Nm3 kgVS−1 and 92–96 % soluble COD removal were recorded. However, the inhibition of methanogenesis was observed due to organic acids accumulation exceeding 21–24 g L−1. BC addition didn’t improve biomethane production in the considered experimental conditions. This study proved that WL is a highly attractive AD substrate, considering its high biodegradability and availability throughout the year, although the process must be carefully operated. [Display omitted] •Wine lees (WL) were suggested as a potential substrate for biomethane production.•The wide range of WL characteristics led to varying biomethane potentials.•Overloads of COD in WL mostly in soluble forms led to inhibition of methanogenesis.•In this study, biochar supplementation didn’t mitigate the process’ instabilities.•High sCOD and wide variability of WL characteristics were critical issues.