Co-liquefaction of livestock manure and food waste: Synergistic effects and product combustion performance

With the depletion of fossil energy, alternative biomass energy has been studied as a potential candidate. Our study focused on the co-liquefaction of livestock manure (cattle manure) and food waste (peanut residue), aiming to obtain high-quality bio-oil and bio-char to maximize resource utilization. By adjusting the ratios of the two types of biomass in a closed system, products distribution in the reaction were controlled to obtain biofuel with high carbon and hydrogen, low oxygen and nitrogen content. Under the optimal reaction conditions (270 degrees C, 30 min, peanut residue/cattle manure = 3/1), the overall yields of bio-oil (a mass fraction of 23.5%) and bio-char (a mass fraction of 18.5%) were obtained, and the higher heating value of the bio-oil reached the highest of 31.74 MJ/kg. It was found that Maillard and Mannich reactions occurred during the co-liquefaction process, and the experimental values of bio-char yield was higher than the calculated values with higher carbon and nitrogen content, indicating the synergistic effect during the formation of the bio-char. The migration and transformation of carbon and nitrogen were explored, and it was found that nitrogen in bio-oil and aqueous phase was trans-ferred to bio-char. All experimental energy recoveries (bio-oils and bio-chars) of co-liquefaction were higher than the calculated ones, indicating that the synergistic effect between peanut residue and cattle manure promoted the energy recovery of the co-liquefaction products.