Single-step bioconversion of cow rumen-based agroindustrial waste to bioethanol via enzyme-assisted processes

Cow rumen waste (CRW), a slaughterhouse by-product rich in lignocellulose, can be directly converted into bioethanol without harsh chemical pretreatment or additional microbial inocula. In this study, we developed an integrated enzymatic hydrolysis and fermentation process to produce bioethanol from CRW using Viscozyme Cassava CL and Saccharomyces cerevisiae. Key process parameters for enzymatic hydrolysis (enzyme concentration, pH, and substrate loading) were optimized, with 3 wt% enzyme at pH 5.0 and 50 g L− 1 CRW yielding the highest glucose release. The enzymatic hydrolysate was then fermented by S. cerevisiae under optimal conditions (inoculum 3 wt%, 30–35 °C, pH 5.0), producing an ethanol concentration of 4.79 g L− 1 with negligible residual sugar. These results demonstrate the feasibility of one-pot conversion of CRW to bioethanol. The novel enzyme-assisted process is scalable and low-cost, offering a sustainable strategy to valorize slaughterhouse waste into renewable bioethanol.