Proceedings

Since 2001, AIR LIQUIDE has been operating several industrial ASPAL-Sludge-plants in Germany and Europe which reduce
the amount of excess sludge considerably.

The patented ASPAL-Sludge-process is effected by injecting ozone into the activated sludge in the bypass which leads to the
biological step of the waste water treatment process. The two main advantages are: 1) disintegration of secondary excess
sludge 2) decrease of filamentous bacteria. A reduction by 40 – 80 % of the secondary sludge excess is attainable.
Actual sludge reduction rates and influences on process parameters are reported with from a number of treatment works...
For this purpose, current operated plants of different industrial sectors have been chosen. Finally, an overview of the operating
expenses of the ASPAL-Sludge-application is given.

KEYWORDS
Excess sludge, surplus sludge, waste sludge, reduction, filaments, disintegration, ozone, waste water treatment