Sustainable Hydrothermal Carbonisation of Industrial Olive Pomace Using Inherent Water Content to Produce Hydrochar for Fuel Application

Resum

In the olive oil industry, processing an olive fruit produces 20% oil and 80% olive pomace (OP) as a residue. Management of OP is challenging due to the presence of very high-water content (60-80%) and toxic phenolic compounds. It is an abundantly available lignocellulosic biomass in the European Union, and its valorisation can promote the sustainable development, bioeconomy and a clean environment. The present study investigated the direct sub-critical hydrothermal carbonisation (HTC) of OP for hydrochar production in order to take advantage of its inherent high-water content and obviate the need for any intermediary steps like drying. The impact of HTC conditions (180–250°C temperature, 2–30 min holding time) on hydrochar characteristics was investigated. The hydrochar produced at 250°C showed better fuel properties, i.e., lesser ash content (2.78–3.52%), higher fuel ratio (0.37–0.40), and HHV (19.18–19.54 MJ/kg). Therefore, the present study found this OP hydrochar to have more potential for fuel application.