Treatment of Cattle Manure by Anaerobic Co-Digestion with Food Waste and Pig Manure: Methane Yield and Synergistic Effect

Abstract

<jats:p>The management of cattle manure (CM) has become increasingly challenging because its production continues to rise, while the regulations on manure management have become increasingly stringent. In Korea, most farms produce CM as a dry mixture with lignocellulosic bedding materials (mainly sawdust), making it impractical to treat CM by anaerobic digestion. To address this problem, this study examined whether anaerobic co-digestion with food waste (FW) and pig manure (PM) could be an effective approach for the treatment of CM. The batch anaerobic digestion tests at different CM: FW: PM mixing ratios showed that more methane was produced as the FW fraction increased, and as the CM fraction decreased. The response surface models describing how the substrate mixing ratio affects the methane yield and synergistic effect (methane yield basis) were successfully generated. The models proved that the methane yield and synergistic effect respond differently to changes in the substrate mixing ratio. The maximum 30-day methane yield was predicted at 100% FW, whereas the maximum 30-day synergy index was estimated for the mixture of 47% CM, 6% FW, and 47% PM (total solids basis). The synergy index model showed that CM, FW, and PM could be co-digested without a substantial loss of their methane potential at any mixing ratio (30-day synergy index, 0.89–1.22), and that a possible antagonistic effect could be avoided by keeping the FW proportion less than 50%. The results suggest that co-digestion with PM and FW could be flexibly applied for the treatment and valorization of CM in existing anaerobic digestion plants treating FW and PM.</jats:p>

A Review of the Sustainable Utilization of Rice Residues for Bioenergy Conversion Using Different Valorization Techniques, Their Challenges, and Techno-Economic Assessment

“…Rice residues in the form of RS have the highest C/N ratio (44.0–74.0) [ 172 ] in comparison with water hyacinth (12–42) [ 173 ], cow manure (24.3) [ 174 ] and pig manure (10.95) [ 175 ]. In the AD process, an optimal C/N ratio in the range of (20–30/1) is needed for bacterial activities.…”

Feasibility of Coupling Anaerobic Digestion and Hydrothermal Carbonization: Analyzing Thermal Demand

“…The assumption considered additive effects in methane production disregarding synergistic effects, which would lead to better results due to the higher gas obtained and lower volume of digestate needing final disposal. Different authors have widely reported synergistic effects when evaluating mixtures of manures and carbon-rich content substrates [87][88][89][90]. Therefore, the remaining amount of solids in the digested slurry should not be significantly affected.…”

Batch and Semi-Continuous Anaerobic Digestion of Industrial Solid Citrus Waste for the Production of Bioenergy

“…The accumulated biogas was quantified as approximately 72.6, 659, 647, and 741 L in the inoculation, startup, and stabilization phases (two batches), respectively. Baek et al [36] found that the biochemical methane potential of the cattle manure though mono-digestion can produce around 109.2 L/kgVS. These same researchers concluded that co-digesting cattle manure with food waste and pig manure proved effective in accelerating the initiation of anaerobic digestion, which suggested that the co-digestion strategy could be applied to promote the start-up of a digester to treat cattle manure.…”