The Impact of Biochar Additives and Fat-Emulsifying Substances on the Efficiency of the Slaughterhouse Waste Biogasing Process

Abstract

Waste management in the agri-food industry is an important technological and environmental problem. Slaughterhouse waste is particularly problematic, as it contains significant amounts of proteins and lipids, neither of which constitute a good substrate for methane production. The physical properties of mixtures of fat and polar solvents inhibit the methanogenesis process. The aim of this research was to assess the impact of the addition of fat emulsifiers and biochar on the amount of biogas produced and the level of carbon conversion per unit of waste weight. The assumed goal was achieved based on a laboratory experiment using static methane fermentation, carried out in accordance with the methodology of the DIN 38414/S8 standard. The results of the experiment indicate that the addition of fat emulsifiers increased the biogas yield from slaughterhouse waste from approximately 370 to 430 dm3 per 2 kg dry weight of waste. Each technological variant resulted in an increase in the amount of carbon that was transformed in the methanogenesis process. Although the level of carbon transformation in the methanogenesis process increased by approximately 20% in objects with emulsifier addition, the use of biochar and fat emulsifiers did not change the amount of methane production. Within the assumed system limits, therefore, the use of fat emulsifiers and biochar seems to be pointless. However, the use of the developed technology can improve the efficiency of biogas production by up to 18% and shorten the process by 5 days. Assuming the continuous operation of the biogas plant, the use of the developed technology will increase the efficiency of biogas production from slaughterhouse waste in the long term by over 30% without the need to modify the infrastructure in the biogas plant.