Integration of cellulosic sugar syrup produced from sugarcane bagasse to molasses-based ethanol production process and improvement in spent wash quality.

• Mixing CSS to molasses did not deteriorate ethanol production. • CSS + molasses mixed medium resulted in ∼27 % lower COD of spent wash. • Resulting spent wash suited biological treatment due to higher BOD/COD ratio. • CSS can be supplemental substrate to molasses-based ethanol production. Cellulosic sugar syrup (CSS), as a potential substrate to many biochemical industries, has been integrated into molasses-based ethanol production. It is seen as an additional substrate to alleviate the shortage of molasses supply. The impact of the CSS integration was assessed in terms of ethanol production and the quality of spent wash obtained after ethanol distillation. In this study, 0.02% (w/v) of urea was supplemented into molasses, as it is the minimum amount that provided high ethanol concentration and fermentation efficiency. Integrating CSS to molasses up to 28.5% (w/v) did not deteriorate the ethanol production nor fermentation efficiency. It also reduces the chemical oxygen demand (COD) of the spent wash by 24% when integrating at least 15% (w/v) of CSS to molasses, comparing to the value of the spent wash from molasses medium. The biodegradability of the spent wash also increased as compared to that of molasses medium. [ABSTRACT FROM AUTHOR]