Process Development for Valorisation of Solid and Liquid Waste Stream in Sugar Factories & Bio-ethanol Industries

Abstract

The objective of this work is the valorisation of some of the waste streams that are generated post the production of bioethanol in sugar factories and distilleries. Boiler ash and process condensate are the two waste streams chosen for this study. This study reports a new approach on extraction of the important components from the boiler ash, containing mainly potassium, by using another waste stream denoted as process condensate. The study shows that the extraction of potassium with process condensate is possible with around 75% potassium extraction efficiency with 80 % potassium purity in a single extraction method. A chief advantage of the current extraction process is that it generates a good quality of distillate, which can be safely recycled back to the fermentation process. This recycled distillate helps in the savings of an additional equivalent amount of fresh process water required for bioethanol fermentation. Analysis of the process condensate reveals that it contains major volatile acidic inhibitors, like acetic, propionic, butyric, iso-butyric, valeric, and iso-valeric acids. These are the major inhibitors for yeast and reduce the efficiency of the bioethanol fermentation process. Following this potassium extraction process, ~90% of these volatile acids are separated and removed. In addition to all the benefits, the process employed in this work helps remove inhibitors, which are microbial contamination, thereby providing the condensate, which can be effectively and safely used as process water back to the fermentation stream to produce bioethanol.