Potential of cellulose from wood waste for immobilization Saccharomyces cerevisiae in bioethanol production

Bioethanol is a sustainable alternative fuel that needs further research. In this work, bioethanol production was carried out through the fermentation of an immobilized yeast cells in alginate/cellulose beads for five cycles. Cellulose was successfully isolated from wood waste and used as a filler to reinforce alginate beads. The effects of alginate/cellulose (AC) ratios (1:0, 1:1, 2:3, and 3:2) on bioethanol yield, concentration, microbial leaching, and surface matrix morphology have been investigated. Infrared analysis results revealed no lignin or lignocellulose in the isolated wood waste cellulose structure, confirming that the extracted cellulose shares the same characteristics as commercial microcrystalline cellulose (MCC). The fermentation rate of alginate/cellulose beads was three times greater than that of neat alginate. The highest bioethanol concentration (increasing up to 114,5 g/L) resulted from AC 3:2 beads for five cycles. The beads can be reused effectively in fermentation for up to four cycles. The results of the microbial leaching test demonstrate that up to 95 % more yeast is effectively kept inside the matrix when a small amount of cellulose is present in the beads in all ratios. These findings indicate that the yeast is strongly interacting with the cellulose matrix, as confirmed via the scanning electron microscopy analysis.