By using ozone the cell walls of the microorganisms are destroyed and the cell constituents are released. The disintegrated sludge then serves as an external C-source for denitrification. Apart from the reduction of the surplus sludge amount, a considerable improvement in the sludge settling behaviour as well as an avoidance of foam formation was shown during the operation of the system.
The special feature of using ozone compared to mechanical disintegration techniques is that tough to degrade materials are partially oxidised by the ozonisation in addition, and are thus opened to biological disintegration. In this way the use of ozone enables high disintegration degrees of up to 35 %.
