Sugarcane bagasse hemicellulose hydrolysate for ethanol production by acid recovery process

In order to increase the reducing sugar concentration in the sugarcane bagasse hemicellulose acid hydrolysate and recover the acid, the acid hydrolysis was carried out in an acid recycle process and detoxification of hydrolysate was performed by electrodialysis. Two cycles of acidic treatments increased the reducing sugar concentration from 28 to 63.5 g l−1 and sulphuric acid consumption decreased to 0.056 g g−1 bagasse. After treatment by electrodialysis, 90% of acetic acid in hydrolysate was removed and the recovery ratio of sulphuric acid was 88%. The pretreated hydrolysates, supplemented with nutrient materials, were fermented to ethanol using Pachysolen tannophilus DW06. A batch culture with pretreated hydrolysate as substrate was developed giving 19 g ethanol l−1 with a yield of 0.34 g g−1 sugar and productivity of 0.57 g l−1 h−1.