Influence of the ultrasound pretreatment on anaerobic digestion of cattle manure, food waste and crude glycerine

To increase the production of methane, when cattle manure (CM) is digested, pretreatments can be applied and/or the manure can be co-digested with other wastes. In this research work, a mixture of CM, food waste (FW) and raw glycerine (Gly) in a proportion in weight of 87% CM, 10% FW and 3% Gly was digested, (a) without pretreatment and (b) with pretreatment by ultrasound, applying a sonication energy of 1040 kJ/kg total solids. Specific methane production was 290 L CH₄/kg volatile solids (VS) without pretreatment and 520 L CH₄/kg VS with pretreatment. With respect to the volumetric methane production, 1.07 L CH₄/L_reactor.day was produced in the first case, and in the second case, 1.98 L CH₄/L_reactor.day. We can conclude that the application of ultrasound pretreatment significantly improved the production of biogas.