Slow pyrolysis of olive mill solid residues as a sustainable valorization strategy for waste biomass

Pyrolysis is a valid thermos-chemical process of energy production that produces biochar from potentially harmful biomasses. This study aims to investigate the pyrolytic conversion of olive mill solid residues (OMSR) into biochar, with the aim of characterizing this product towards applications for soil improvement and soil C sequestration. Production parameters of OMSR-biochar (OB) and physico-chemical characteristics were analyzed and compared with published data to assess the potential of OB to serve as a soil amendment and soil C sequestration method. The slow pyrolysis of OMSR at 450 degrees leads to a good proportion between produced products (fuels liquid and gas, and solid), and generates about the 35% of OB. In turn, this product reveals the absence of phytotoxicity, the presence of exchangeable surface cations, structure, particle size distribution and external surface groups suitable for agricultural uses, and high C content with a potential long lasting in soil. The physico-chemical characteristics of OB reported here suggest that OB could be used for improving soils and increasing C sequestration in a sustainable way.