Hydrothermal liquefaction of Moroccan two-phase olive mill waste (alperujo): Parametric study and products characterizations

The primary objective of this study is to investigate the hydrothermal liquefaction of two-phase olive mill waste (TPOMW). Consequently, a parametric study of the two-phase olive mill waste hydrothermal liquefaction was conducted using a batch reactor to screen different experimental operating conditions. Experiments were conducted at different temperatures: 260, 280, and 300 degrees C, dry-matter/water ratios: 0.05, 0.10, and 0.15, and residence times: 0 (no isotherm step), 30, 45, and 60 min. The product (gases, bio-oils, hydrochar) yields, global carbon mass balances, elemental composition (CHNS-O), and energy yield obtained were evaluated for each experimental condition. The operating condition at 280 degrees C with 0.15 dry-matter/water ratio and no isotherm step resulted in the maximum energy yield of the process (87%). Under these conditions, the bio-oil and hydrochar yields were equal to 37.2 wt% and 22.6 wt% of initial dry matter, respectively. Analysis of the products showed that the produced bio-oil (30.8-32.1 MJ/kg) and hydrochar (27.7-30.6 MJ/kg) presented higher values than lignite and coal, thus, these products can potentially be used for energetic insights. In terms of BO composition, FT-IR analysis exhibited the presence of some compounds such as carboxylic acids phenols, and esters. GC-FID/MS analysis showed that the produced bio-oils are rich in phenolic compounds, oleic acid, hexadecanoic acid, fatty acid methyl ester, and fatty acid ethyl ester, which is in accordance with FT-IR analysis.

Automated summary

The primary objective of this study is to investigate the hydrothermal liquefaction of two-phase olive mill waste. A parametric study was conducted to screen different experimental conditions using a batch reactor. The results showed that the highest energy yield was achieved at 280 degrees C, with a dry-matter/water ratio of 0.15 and no isotherm step. The produced bio-oil and hydrochar had high energy values and could potentially be used for energy purposes. Furthermore, the bio-oil was found to contain phenolic compounds and fatty acids.