Mass Balances in the Production of Second-Generation Bioethanol from Agroindustrial Waste

Abstract

The production of second-generation (2G), bioethanol from agroindustrial waste, is presented as a sustainable biotechnological strategy for the valorization of lignocellulosic biomass. This research comprehensively evaluated the mass balances at key stages of the 2G bioethanol production process, using rice husks, corn stover (chala), and sugarcane stover, abundant in the agroindustry, as raw materials. The studied process included reception and grinding, enzymatic hydrolysis to release fermentable sugars, alcoholic fermentation, distillation to concentrate ethanol, dehydration to achieve the required purity, and denaturation for use as a biofuel. Precise mass and volume measurements were made at strategic points throughout the process to quantify flows and determine mass balances at each stage. The results indicated an overall biomass-to-bioethanol conversion efficiency of 5.35 %, identifying the distillation stage as a critical point with the greatest impact on overall process efficiency. Milling showed a 1 % mass loss, while fermentation achieved a sugars-to-bioethanol conversion efficiency of 5 %. Mass balance analysis proved to be a fundamental tool for the detailed evaluation and identification of process optimization opportunities, suggesting that improving efficiency at the fermentation stage and pre-treatment could have a significant impact on the overall yield and economic viability of the process.