Use of Immobilized S. cerevisiae in Beads Made fromPolyvinyl Alcohol and Palm Oil Fuel Ash to Enhance EthanolProduction from a Distillery Wastewater

摘要

The purpose of this study was to use an immobilized yeast culture (S. cerevisiae) to explorethe potential to produce ethanol by fermenting a distillery wastewater either in batch or continuous-flow reactors.The beads were made using a mixture of polyvinyl alcohol (PVA) and palm oil fuelash (POFA)in order to enhance the beads’ potential use. Results revealed that a 50% (v/v) cell con-centration in the beads appeared to be the most suitable, while a PVA to POFA ratio of 10:3 (i.e. thehighest POFA content investigated) was superior with respect to bead physical characteristics andperformance, which was also validated by photomicroscopic images. The yeast cells were grown onboth the outer and inner surface, especially at the cell concentration of 50% (v/v). Regarding thecombined effect of PVA:POFA ratio and initial cell dry weight, a slight improvement in ethanolproductivity (g/L/h) and ethanol yield (g/g) was observed with an increase in the POFA contentand initial cell dry weight. Furthermore, ethanol productivity was significantly higher in a seriesof batch reactors operated at an HRT of 6 h compared to HRTs of 12 and 24 h.