Semi-simultaneous Saccharification and Fermentation of Ethanol Production from Sargassum horneri and Biosorbent Production from Fermentation Residues

Abstract

One of the fundamental goals of bio-ethanol production is to find the alternative of traditional land-relied feedstock. A kind of macroalgae, Sargassum horneri (S. horneri) was chosen as the bio-source for ethanol production in the present investigation. The bioethanol was achieved by acid-pretreated, hydrolysis, and semi-simultaneous saccharification and fermentation (S-SSF) at small pilot scale. Immobilization of Pichia stipites in calcium alginate was adapted in the S-SSF process. Furthermore, effects of pre-hydrolysis time, cellulase loading, fermentation temperature and fermentation time on the concentration, and yield of bio-ethanol were evaluated by using response surface methodology (RSM). A maximum bioethanol concentration (2.89 g/L), and maximum bioethanol yield (0.11 g/g raw material) at cellulase loading (10 IU/g raw material), pre-hydrolysis time (53 min), SSF temperature (32 °C) and SSF time (14 h) were observed. The optimized bioethanol production data series fit the Gompertz model and modified Logistic model with an R2 value of 0.997. The obtained Gompertz and modified Logistic coefficients indicated that S. horneri can serve as an efficient substrate for bioethanol production. The fermentation residues were used for typical dyeing contamination adsorption, the existence of the residual lignin and exposure functional groups made it an effective adsorbent, which followed the pseudo-second-order kinetics. These results are helpful for the scale-up development of lignocellulosic macroalgae based bioethanol production and fermentation residue use.