It could be shown, that with an increasing ultrasound
specific energy input of 1Wh the SCOD increases linearly with
a value of 9 mg/L. As described before, a higher concentration
of bioavailable substances (measured by SCOD) can negatively
affect the fermentation process. Therefore, an optimal value
of ultrasound specific energy input should be used with
respect to the biogas yield (see Fig. 2).