Effect of ultrasound amplitude and reaction time on the anaerobic fermentation of chicken manure for biogas production

In this study, a biological waste material, chicken manure, was sonicated in aqueous solution at 24 kHz. The effect of ultrasound amplitude and reaction time were investigated in terms of biogas yield and methane content. Best results were found at high amplitudes and high reaction times by trend, where the biogas yield could be increased up to 41% (278 NL/kg ODM (untreated), 393 NL/kg ODM) with a required energy input of 0.08–0.25 kWh/kg ODM (organic dry matter). Moreover, the methane content could be increased in most instances, at best, from 66.9% (untreated) to 70.4%. Consequently, the use of ultrasound could increase the total methane yield up to 46% (186 NL/kg ODM (untreated) to 271 NL/kg ODM (sonicated)). In this study, the correlation of the biogas yield with SCOD and particle size were investigated and the effect of ultrasonic waves on the nutrient relationship (C:N:P) was evaluated, too. At least, comparison of energy was done, where it could be shown that the ultrasound disintegration leads to a significant increase in the net energy yield with respect to the conventional biological hydrolysis.