Enhancement of the saccharification yields of Ulva pertusa kjellmann and rape stems by the high-pressure steam pretreatment process

Abstract

The high-pressure steam process was used to hydrolyze rape stems and Ulva pertusa kjellmann using only water. The biomass was hydrolyzed in a compressed cell at a high temperature and high pressure. The optimal pretreatment conditions were determined to be 180 and 10 bar for 8 min, with 8.5 and 7.4% (w/w) glucose conversion yields, respectively. After the pretreatments, the residues were easily hydrolyzed by treating the enzymes with 1 FPU/mL cellulase, and the 56.8 and 77% (w/w) total cellulose in the results were converted into glucose in 24 h. These results imply that using only water and not any other chemical can efficiently hydrolyze rape stems and Ulva pertusa kjellmann because the high-pressure steam pretreatment process can easily decompose the cellulose structure via XRD analysis, which will result in a high conversion yield with low doses of cellulase. This process was proven to generate a low amount (16.9 ppm) of HMF (hydroxymethylfurfural), which resulted in ethanol production with a 48.7% theoretical maximum conversion yield of glucose. It is believed that this process can be widely used to hydrolyze other agricultural and marine resources for bioethanol production.