Acidogenic Fermentation of Kitchen Waste for the Production of Volatile Fatty Acids: Bioaugmentation by Bacillus GIEC

Abstract

In this study, the lignocellulosic (banana peel, tea residue, and paper towel in a ratio of 1:1:1) and protein (chicken breast) components of kitchen waste (KW) were used as substrates for mesophilic anaerobic fermentation to produce volatile fatty acids (VFAs). The ability of a new strain belonging to Bacillus sp. to improve the degradation of kitchen waste and VFAs production was investigated. The results showed that the addition of Bacillus cell wall depolymerization GIEC (Bacillus GIEC) to the fermentation system could result in higher concentrations of soluble chemical oxygen demand (sCOD), improved the removal rates of volatile solids (VS), and increased yield of VFAs from the substrates. Compared with the control group, the sCOD concentrations of lignocellulosic and protein substrates increased by 132.58% and 18.36%, respectively; the volatile solids removal rates of lignocellulosic and protein substrates increased by 84.96% and 135.53%, respectively; the yield of VFAs of lignocellulosic and protein substrates increased by 61.29% and 35.92%, respectively, reaching 0.31 g/g VSadded and 0.67 g/g VSadded, separately. According to the study, the addition of Bacillus GIEC enhanced the solubilization of solid organic matter during hydrolysis process, further resulting in a higher yield of VFAs compared to the control group. Furthermore, the micro-aerobic test showed that the bioaugmentation ability of Bacillus GIEC has little effect by the presence of oxygen. The Bacillus GIEC has the potential for bioaugmentation of the VFAs production from kitchen waste.