Sequential hydrogen and methane production using the residual biocatalyst of biodiesel synthesis as raw material

Residual Fermented Solid (RFS) is the used biocatalyst obtained after enzymatic biodiesel production carried out applying the fermented solid (FS) with lipase activity. Approximately 350 g of RFS are generated for each liter of biodiesel produced from palm residues fermented solid. In this study, this residue was used for the first time as a raw material for biological hydrogen production through dark fermentation and sequential application of the hydrogen production liquid waste (HPLW) for methane obtainment via anaerobic digestion. The RFS was composed mostly of oils and fats (60% wt.%), and carbohydrates, such as mannose, glucose, and xylose. Hydrogen yield reached 239 +/- 44 mL H-2/L after 24 h of fermentation using 31 gRFS/L at the beginning of the process. Additionally, 204 +/- 13 mL CH4/g COD were produced through the anaerobic digestion of HPLW, which represented 61% of efficiency. (C) 2021 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.

Automated summary

In this study, residual fermented solid (RFS) was utilized for biological hydrogen production and methane obtainment, with hydrogen yield reaching 239 +/- 44 mL H-2/L and methane production efficiency at 61% using waste resources for energy conversion.