Enhancing Biobased Volatile Fatty Acids Production from Olive Mill Solid Waste by Optimization of pH and Substrate to Inoculum Ratio

The pH and substrate-to-inoculum ratio (S/I) are important parameters in the anaerobic fermentation of agroindustrial residues, therefore optimization these two is needed for a stable, efficient, sustainable reactor operation. In this work, (5–9) S/I (0.5–3 gVS gVS−1) were optimized to produce biobased volatile fatty acids (VFAs) from hydrothermally pretreated olive mill solid waste (HPOMSW). response variables evaluated Doehlert design total VFAs concentration (tVFAs) (mg L−1) amounts (%) isobutyric, butyric, isovaleric, valeric on profile. was variable that most influenced mixed culture HPOMSW, proving be key parameter process. Microbial community analyses conditions 1 (S/I = 3 gVS−1 7) 4 1.13 5) showed Proteobacteria Firmicutes accounted more than 87% microorganisms identified both conditions. addition, second-order model best fitted experimental data production at desirable condition 8).