Valorization of Solid Residues from Anaerobic Digestion through Thermal and Hydrothermal Carbonization Processes
Miliotti, E., Casini, D., Lotti, G., Bettucci, L., Pennazzi, S., Rizzo, A.M., Chiaramonti, D.
Efficient digestate management from anaerobic digestion (AD) is one of the most important priorities for medium term bioenergy and bioproducts field development. Carbonized solid digestate results to be a sterilized and easily transportable value-added product: the so-called biochar. In this study, two digestate carbonization processes have been tested in lab and pilot-scale at different process conditions: slow pyrolysis carbonization and hydrothermal carbonization (HTC). The digestate came from an AD plant located in Italy, fed mainly with barley silage and, in smaller quantities, wheat and herbaceous silage and poultry manure. The digestate had a moisture content of 72.6 % w.b. w/w. The slow pyrolysis was carried out, with the feedstock dried at 75 °C for 48h, in a 1.5 kg h-1 plant, with a heating rate of about 7 °C min-1 to reach the maximum process temperature of 500 °C, which was maintained for 1 h. HTC, instead, is a technology capable of directly exploiting the digestate high water content. HTC experiments were carried out in a 27 ml micro-reactor, testing different temperatures and residence times (200-250 °C and 0.5-3 h, respectively). Yields and characteristics of the products were analyzed and discussed. Some char properties were also compared to European and International biochar standards.
pyrolysis, char, digestate, biochar, characterization, hydrothermal carbonisation
Biomass Conversion Technologies for Liquid and Gaseous Fuels, Chemicals and Materials
Production of thermally treated solid biofuels
25th European Biomass Conference and Exhibition
1063 - 1069
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