Vacuum pyrolysis of olive pomace for biochar production: Enhancing carbon stability and soil nutrient supply
Year: 2025
Type: article
Abstract: Olive pomace (OP), a significant agro-industrial byproduct in Mediterranean countries, poses considerable disposal challenges and offers potential as a feedstock for engineered biochar production. Conventional pyrolysis of OP has been widely studied and often yields biochar with limited aromaticity and variable nutrient content. However, no prior work has explored the potential of vacuum pyrolysis for this residue. Addressing this research gap, this study investigates the use of vacuum pyrolysis (500°C, 15–20 kPa, 2 h) to transform OP into a stable and nutrient-rich biochar. The process yielded 30.9 wt.% biochar with 68.7% fixed carbon, representing an improvement of 20% in carbon retention compared with atmospheric pyrolysis. Elemental ratios (H/C = 0.03 and O/C = 0.18) confirmed high aromaticity and long-term stability, while mineral enrichment underscored high agronomic value. The biochar displayed a cation exchange capacity of 56.2 cmolc/kg and 79% porosity, properties favorable for nutrient cycling, and soil remediation. The carbon sequestration potential was estimated at 2.6 tCO₂eq per ton of biochar applied and heavy metals were below international thresholds, ensuring environmental safety. Beyond material characterization, the work highlights engineering advantages, including reduced inert gas requirements and a reusable syngas fraction (64.6 wt.%) that can offset energy costs. However, as the study was conducted at a single pressure level, the specific contribution of vacuum conditions requires further confirmation through multi-pressure trials. Such results position vacuum pyrolysis as a promising technology for waste valorization, carbon management, and climate-smart agriculture, while future research should address field validation, contaminant screening, and life-cycle performance.
Source: Results in Engineering
Institutions: Tunis University, University of Carthage, National Research Institute of Rural Engineering, Water and Forests, Tunis El Manar University, University of Sfax, Centre National de la Recherche Scientifique, Université Paris-Est Créteil, Sorbonne Université, Institut National de Recherche pour l'Agriculture, l'Alimentation et l'Environnement, Institut d'écologie et des sciences de l'environnement de Paris, Institut de Recherche pour le Développement, Laboratoire d'étude des Interactions Sol - Agrosystème - Hydrosystème
Language: English
Subfield: Fuel Technology
Field: Energy
Domain: Physical Sciences
Open Access status: gold
Estimated APC paid: $1,940
OpenAlex ID: W4417138396