Sewage purification

Wastewater treatment plant

In biological nitrogen elimination, carbon must be provided for the denitrification stage. Normally, methanol or other chemicals have to be purchased for this purpose. Ultrasound, on the other hand, releases excess bacteria biomass (excess sludge), whereby cell ingredients are made available as carbon carriers and fed to denitrification. At the same time, nitrogen degradation is increasing.

Nitrogen degradation

The biological nitrogen degradation takes place through nitrification and denitrification. A successful degradation process requires an additional carbon supply to be provided for the denitrification stage. Normally, methanol or another external carbon source is bought in and added to the process for this purpose. Sonication of the excess sludge with ultrasound breaks down the biomass. This releases the cell contents – i.e. ideal carbon carriers –, which are then available as an internal source of carbon in the denitrification stage. Biological nitrogen degradation in the wastewater treatment plant can therefore be maintained or even intensified. If part of the sonicated sludge is returned to the biological phase, the quantity of sludge to be disposed of is automatically reduced. Use of ultrasound for the degradation of nitrogen was successfully tested in practice and, for example, has been in operation in Bünde municipal wastewater treatment plant since 2006.


Ultrasound can also be used for the disinfection of turbid and highly concentrated media, e.g. process water and wastewater, where the standard chlorine and UV methods fail. Germs attach to suspended particles or flocks and therefore easily escape disinfection by UV. Ultrasound can be used to break down these agglomerations, so that the germs exist in isolation and resuspended. This makes them accessible to the classic methods once again and they can be successfully attacked. Whether ultrasound is used alone or in combination with conventional variants – effective disinfection is ensured.

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