Organic loading optimization is the key to unlocking the VFAs potential of poultry manure during alkaline fermentation

This study investigates the potential of poultry manure (PM) for volatile fatty acids (VFAs) production through alkaline fermentation, offering a sustainable alternative to methane production. The study explores the effects of organic loading rates (OLR) and food-to-inoculum (F:I) ratios on VFAs yield, optimizing conditions for enhanced process efficiency. Batch fermentation assays indicated that a low F:I ratio of 0.3 produced the highest VFAs yield, particularly under alkaline conditions (pH 9.5). In semicontinuous fermentation, a stepwise increase in OLR demonstrated that an OLR of 8 g VS L⁻¹ d⁻¹ was optimal for maximizing VFAs production. Microbial analysis revealed an increase in sulfate-reducing bacteria, particularly Desulfosporosinus , at high OLRs, while hydrolytic genera such as Bacteroides and Sphaerochaeta adapted to OLR stress. In contrast, syntrophic bacteria such as Sedimentibacter and Syntrophomonas decreased under these conditions. These shifts highlight the complex microbial interactions that influence fermentation performance. The findings indicate that PM is a viable substrate for VFAs production, and alkaline fermentation, coupled with optimal OLR and microbial community management, can enhance process sustainability. These results contribute to the growing body of research on valorizing livestock waste for bio-based chemical production.