Colin Froud1 and Ralf Weber2,Walti Schmitt3
1CSO Technik Ltd, 2Biogest AG 3Wiesbaden WWTW


This paper is the third and final paper in a series detailing the installation of the Crown disintegration system in Wiesbaden and its operational impact.

The Crown sludge disintegration system utilises mechanical forces to cause cavitation in surplus activated sludge (SAS). Cavitation ruptures the cell structure releasing the otherwise locked in resource for digestion enhancement or as a carbon source for biological treatment enhancement.

This paper discusses the performance data from the first full scale plant for biological treatment enhancement. The first full scale Crown disintegration system for digestion enhancement was installed in March 2002 and since then a further ten plants have been installed and are full operational throughout Europe.

In the autumn of 2003 the first full scale Crown Disintegration plant was installed, for the city of Wiesbaden, in its Biological treatment enhancement role. The city of Weisbaden suffers from population loss during summer and winter months leading to problems with final effluent quality. The biological tanks have previously suffered with considerable foaming problems when the carbon levels were low. Weisbaden had tried a number of solutions to the problem including diverting primary sludge to the biological phase and the import of Methanol as a carbon source. Both solutions improved the effluent discharge quality however the former caused problems due to ragging of various plant equipment and the latter was very expensive.

The Crown system was installed in 2003 and was operational for the winter months when the nitrogen discharge limits are most at risk. The system was monitored by the City of Wiesbaden over the key risk period. The paper will discuss the details of the operation and confirm the systems ability to release carbon from thickened RAS as a substitute for other imported carbon sources.

The biological aeration input volume of the tanks at Weisbaden is automatically regulated by the Ammonia level monitoring equipment. Since the Crown system has been installed substantial reductions have been noted in the volume of oxygen required and significant energy savings have been realised.

The Environmental Laboratories of the City of Wiesbaden has now completed its studies on the operational impact and performance that has provided some excellent results. This paper records the results of the year long trial and details the operational improvement and performance of the Crown system

KEY WORDS Carbon source, Crown, Digestion enhancement, Disintegration, Total Nitrogen, Wiesbaden.

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