Proceedings

Anaerobic sludge digestion is the most widely applied process for the stabilization of the solids generated during wastewater
treatment. The anaerobic stabilization process has a rate-limiting step in enzymatic-biological sludge hydrolysis and due to
this step it is in general a slow process that makes necessary the provision of large digesters to achieve the level of treatment
required by regulations.

The use of high-power ultrasound for disintegrating sludge bacteria cells by cavitation is a relatively new application in sewage
sludge treatment that helps to enhance the performance of the digesters. In several full-scale applications of this technology
an accelerated rate of anaerobic sludge digestion has been observed, with less digested sludge being produced and
increased biogas production being attained. This paper reports on the disintegration and anaerobic degradation of waste
activated sludge in pilot scale studies in order to seriously quantify the process by setting up mass balances as well as in
results from full scale installations utilizing this technology. In both instances the application of ultrasound for sludge
disintegration demonstrated a marked increased in the volatile solids destruction and in the production of biogas.

KEY WORDS
Anaerobic Digestion, Disintegration, Sludge, Ultrasound.