The Synergistic Effect of Simultaneous Ultrasound Heating and Disintegration on the Technological Efficiency and Energetic Balance of Anaerobic Digestion of High-Load Slaughter Poultry Sewage

Abstract

Regulations in force urge for thermal pre-treatment of post-slaughter waste prior to its anaerobic digestion. Increased interest in biomethane as a fuel in gas networks or vehicles of road transport forces the need to look for heating methods that are alternative to heat recovery from cogeneration. The goal of this study was to determine the synergistic effect of simultaneous ultrasound heating and disintegration on the technological efficiency and energetic balance of the anaerobic digestion of high-load slaughter poultry wastewater. The highest efficiency of anaerobic digestion was obtained for the ultrasound thermal pre-treatment (60 min, 90 °C, OLR = 2.0 gCOD/dm3). In this experimental variant, the biogas production rate reached 9.0 ± 0.2 cm3/gCOD·h, biogas yield was 492 ± 10 cm3/gCOD, and the biogas produced contained 69.8 ± 1.4% CH4. Given the incurred energy outputs, the highest net energetic efficiencies, i.e., 5.92 ± 0.43 Wh and 5.80 ± 0.42 Wh, were obtained in the variants with the conventional thermal pre-treatment (60 min, 70 °C, OLR = 6.0 gCOD/dm3) and ultrasound thermal pre-treatment (60 min, 70 °C, OLR = 6.0 gCOD/dm3), respectively.

The Use of Hydrodynamic Cavitation to Improve the Anaerobic Digestion of Waste from Dairy Cattle Farming—From Laboratory Tests to Large-Scale Agricultural Biogas Plants

“…To date, many techniques have been analysed to improve the susceptibility of organic substrates to degradation under anaerobic conditions. These include comminution and mechanical destruction [24], treatment with acids and bases [25], advanced oxidation [26], enzymatic hydrolysis [27], disintegration with ultrasound [28,29], hydrothermal depolymerisation by conventional [30] and microwave heating [31], the use of low temperatures in the freezing processes [32] and the injection of solidified carbon dioxide [33,34], as well as the use of high-voltage disintegration [35]. Unfortunately, in many cases, the optimistic results of the preliminary investigations, which were achieved under laboratory conditions, were negatively confirmed in pilot studies on a technical scale [36].…”