ORGANIC SOLID WASTE MECHANICAL PRETREATMENT FOR THE OPTIMIZATION OF ANAEROBIC DIGESTION PROCESSES

Anaerobic digestion has been recognized as the most demanding process for the valorization of organic solid waste towards the production of several, valuable intermediates (Dahiya et al., 2018), which can be further converted to a methane rich-gas to meet the current needs for renewable energy production. The enhancement of methane generation is of great interest and it can be pursued via different strategies, including the pretreatment of the waste destined to the process. Press-extrusion has raised as a promising mechanical pretreatment, separating organic waste into a homogeneous liquid fraction addressed to wet anaerobic processes and a solid one, usually sent for composting. Recent studies highlighted that the anaerobic digestion yields of press-extruded organic waste can be enhanced by increasing the organic loading rate to the digester (Novarino and Zanetti, 2012) as well as by mixing the liquid and the solid fractions from this pretreatment (Mu et al., 2018). This study aimed at verifying the significance of both the organic loading rate and the mixing ratio between the liquid and solid fraction from press-extrusion by using a factorial design of experiment. Results were discussed and statistically elaborated to identify the operating conditions to be further tested for the integrated process optimization.