TECHNOLOGICAL PROCESSES AND EQUIPMENT FOR BIOETHANOL PRODUCTION

Abstract

Climate change and the limited amount of fossil fuels have led to the development of renewable energy, one of the directions of which is the production of bioethanol. The raw materials from which bioethanol is produced are divided into four generations of biomass. The use of first-generation biomass - food products is inappropriate. The current issue is the development of  technologies from resources of the second-fourth generations. The aim of the article is to analyze the prospects for the development of bioethanol production from agricultural raw materials. For the production of bioethanol, molasses is one of the best raw materials for processing. Along with the high sugar content, beet molasses contains all the substances necessary for the normal functioning of yeast. Molasses does not contain dextrins, unsweetened starch, so it ferments faster, the loss of fermentable carbohydrates is  reduced, and the yield of alcohol in terms of conditional starch increases. Due to the fact that the phosphorus content in  molasses is insufficient for the normal development of yeast, the technology provides for the addition of 0.06-0.08% P2O5 in the form of superphosphate, diammonium phosphate and orthophosphoric acid. The fermentation of the wort takes place in fermenters. Bioethanol fermentation can be carried out in a periodic mode, a periodic mode with feeding or a continuous  mode. Characterization of the biological agent, Saccharomyces, a genus of yeast belonging to the family Saccharomycetaceae, phylum Ascomycota, kingdom Fungi. Maximum ethanol concentrations are  observed in the medium of Saccharomyces cerevisiae and Zymomonas mobilis.The vital activity of yeast is influenced by the active acidity of the medium. If the pH shifts to the alkaline side, the formation of glycerol increases. The vital activity of yeast is maintained within the pH range of the medium from 2 to 8; the optimal pH for their cultivation is 4.8 -5.0. At a pH below 4.2, yeast continues to develop, while the growth of acid-forming bacteria stops.The technology for producing bioethanol by microbial fermentation consists of three main stages. The first and main one is the production of a fermented sugar solution. The fermentation of sugars to form ethanol in the solution is the second stage, which takes place at constant temperature, pH and sugar concentration. The separation and purification of ethanol from the solution is the final, third stage, which is usually achieved by distillation.