Ultrasonication Pretreatment as a Tool to Boost COD Solubilization and Biogas Production in Anaerobic Digestion

Anaerobic digestion is a well known and widely recognized biological process that allows a direct waste to energy nexus, through the conversion of organic wastes into biogas. Depending on the wastes used as a substrate and on their degradability, kinetics and process yields may vary consistently, affecting the economic sustainability of the process. Pre treatments of the organic substrates may boost their degradability, enhancing and speeding up biogas production. The application of ultrasonication has been widely studied to increase the hydrolysis rate in anaerobic digestion processes. In this study, a mixture of Poultry Manure (PM) and Sewage Sludge (SS) was treated at different ultrasonic densities (180, 340, 500, and 1000 W L-1). The overall highest increase in the soluble COD was obtained at 1000 W L 1, with a degree of disintegration of 23.6 %. The treated wastes were then tested to define their biological methanation potential (BMP) and to define their hydrolysis coefficient. The outcomes of the test indicate a significant increase in the specific methane production and the hydrolysis activity (+ 22.8 % and + 32.3 %, respectively).