Exhausted Grape Marc Derived Biochars: Effect of Pyrolysis Temperature on the Yield and Quality of Biochar for Soil Amendment

Abstract

The present study focuses on the valorisation of winery industry wastes through slow pyrolysis of exhausted grape marc (EGM). The optimal pyrolysis parameters were firstly identified by small scale experiments carried out using thermogravimetric analysis. Nine pyrolysis temperatures were tested and their influence on the decomposition of the EGM residue and biochar yield was evaluated. Then, biochar production was conducted in a pilot plant at three chosen temperatures (450, 500 and 550 °C) at which the biochar was shown to be stable. The effects of biochar application to soil with respect to plant (ryegrass) growth was also evaluated. Pyrolysis of EGM at the 450–550 °C temperature range has been shown to generate thermally stable and nutrient-rich biochars, but only the biochar produced at 450 °C showed a marked benefit effect of ryegrass growth.