Scale-up of hydrothermal processing: Liquid hot water and pilot-scale tubular steam explosion batch reactor for bioethanol production using biomass

Sargassum spp. is a biomass that can potentially use as an alternative for bioethanol production. Hydrothermal processes (liquid hot water and steam explosion pretreatment) were carried out at different operational condi-tions. Enzymatic hydrolysis performed a preliminary test with different ratios 1:1 and 1:2 (cellulases and hemicellulases) of enzyme loading, once selected 1:2 ratio was obtained conversion yield of 99.91% and therefore carried a scale-up in stirred bioreactor getting 95.92% saccharification yield. Pre-simultaneous saccharification and fermentation strategy was performed in a continuous stirred tank bioreactor (CSTBR), producing ethanol yield of 57.69%, and for simultaneous saccharification and fermentation strategy was per-formed in a bubble column reactor was 71.37% ethanol yield. The energy efficiency was analyzed in different scenarios; the best data was 30.19 (gsugar/MJ) in the bioreactor enzymatic hydrolysis process. This development allows for establishing the conditions for a third-generation biorefinery on a circular bioeconomy using Sargassum biomass.

Automated summary

Hydrothermal processes were used to treat Sargassum spp. biomass under different conditions, achieving a conversion yield of 99.91%. The enzymatic hydrolysis was scaled up in a stirred bioreactor, resulting in a saccharification yield of 95.92%. The simultaneous saccharification and fermentation strategy yielded ethanol yields of 57.69% in a continuous stirred tank bioreactor and 71.37% in a bubble column reactor. The bioreactor enzymatic hydrolysis process showed the best energy efficiency at 30.19 (gsugar/MJ). This study establishes the conditions for a third-generation biorefinery using Sargassum biomass in a circular bioeconomy.