Bioconversion Pathways for Cassava Pulp Valorisation: Biomethane, Lactic Acid, Butyric Acid, and Caproic Acid

Cassava pulp (CP), a significant agro-industrial waste generated in Thailand, presents environmental challenges due to its high organic content and rapid fermentability. While CP is traditionally repurposed for low-profit applications such as animal feed and mushroom cultivation, alternative sustainable management strategies are needed. This study explores the bioconversion of CP into valuable bio-products, focusing on methane, volatile fatty acids (VFAs), lactic acid (LA), and caproic acid (CA). Physical pretreatment methods, including ultra­ sonication and microwave processing, enhanced CP degradation. Ultrasonication at 10 min (US10) and micro­ wave treatment at 90 ◦C (MW90) significantly improved solubilisation, increasing methane yield to 327.03 NmL CH4/gCOD and enhancing VFA production, particularly butyric acid (BA). LA production from CP was also optimised through nutrient supplementation and microbial enrichment, with Lactobacillus identified as a key contributor. CP-derived LA, BA, and acetic acid (AA) fermentation successfully facilitated CA production via chain elongation. Microbiome analysis revealed the dominance of Ruminococcaceae, Lactobacillus, Bifidobacte­ rium, and Prevotellaceae in CA production. This study demonstrates the feasibility of upgrading CP waste through anaerobic fermentation and chain elongation. CP can be repurposed into high-value bio-products by integrating effective pretreatment and fermentation strategies.