Sugarcane Ethanol Production

Sugarcane feedstock mainly consists of sugar in the form of disaccharide (sucrose), which is readily fermented into ethanol by S. cerevisiae. The process of making ethanol from sugarcane starts when cane stalks are crushed to extract a sugar-rich cane juice. When cane stalks passed through extractor/expeller, cane juice is collected and delivered to a fermentation tank where the yeast fermentation reaction occurs to generate ethanol. The leftover fibrous residue called bagasse (45-50% moisture content) after juice extraction process is commonly combusted to generate heat/electricity for in-plant use. After fermentation, the fermentation broth containing approximately 5-12% ethanol by weight is now called beer. The beer is delivered to distillation column where the ethanol is recovered and the liquid residue known as vinasse is co-generated at the bottom of distillation column. At this process, the purity of ethanol can be up to 92-95% therefore further water separation process is required. Commonly, dehydration of the residual water is carried out using molecular sieves resulting in the final product, a fuel-grade anhydrous ethanol (200 proof or >100% ethanol).

Sugarcane Ethanol Residues

There are two principal residues from sugarcane-to-ethanol production including bagasse (solid residue) and vinasse (liquid residue). Normally, bagasse is used to provide heat/steam/electricity for the ethanol plant. However, vinasse could not be used as an energy source and has to be treated before disposal. Therefore, vinasse is still a major burden for sugarcane ethanol production.


Vinasse also known as stillage or distillery spent wash is generated as a leftover at the bottom of distillation column following ethanol recovery process. Vinasse characteristics are:

  • Dark colored
  • Low pH (4.0-4.5)
  • High total solids
  • Extremely high organic content
  • High nitrogen content (derived from yeast cells leftover from fermentation process)

  • Fig. 1 The schematic diagram of sugarcane ethanol production

    Fig. 2 Vinasse from sugarcane-ethanol industry