Anaerobic Conversion of Sugarcane Vinasse into Medium-Chain Organic Acids
The valorization of agro-industrial residues through anaerobic bioprocesses offers a sustainable route for producing high-value biochemicals. Sugarcane vinasse, a high-strength effluent from ethanol production, represents a promising substrate for the generation of medium-chain fatty acids (MCFAs). This study evaluates the production of MCFAs from sugarcane vinasse using a two-stage anaerobic reactor system designed to separate acidogenesis and chain elongation processes. In the first stage, acidogenic fermentation converted organic matter into short-chain carboxylic acids, mainly acetate, propionate, and butyrate. The second stage promoted chain elongation via reverse ß-oxidation, enhancing the formation of medium-chain acids such as caproate and caprylate. Key operational parameters, including pH, hydraulic retention time, and organic loading rate, were optimized to improve product selectivity and minimize methanogenesis. The two-stage configuration improved process stability and increased carbon recovery as valuable acids compared to conventional single-stage systems. These findings demonstrate the technical feasibility of integrating staged anaerobic reactors for vinasse valorization, contributing to circular bioeconomy strategies in the sugarcane ethanol industry.