Bio-stimulation of anaerobic digestion by low intensity ultrasonication

Low intensity ultrasonication (US) was applied to stimulate the biological activities in anaerobic digestion (AD) process. The enhancement in methane production was used to investigate the sono-biostimulation effects on the process performance. The 32% higher CH₄ production was observed over control at best US intensity and irradiation time of 0.0028 W/mL and 120 s, respectively. The sono-biostimulation effects in terms of higher CH₄ generation over control lasted for 45 h. The increase in the concentration of NH₄ ⁺-N and K⁺ considered the indication of cell lysis under applied US conditions. At best US intensity and irradiation time, the NH₄ ⁺-N and K⁺ fraction in the medium remained similar as of control, which indicated that no cell lysis occurred. The preliminary findings of the study showed that low intensity US can be a promising solution to enhance the process efficiency in terms of higher methane production with minimal energy requirement.