Statutory regulations for phosphorous and nitrogen elimination and changes in the process engineering of waste water treatment make the mechanical thickening of sewage sludge unavoidable. For example, the controlled thickening with decanters can reduce the volume of the surplus activated sludge by 90% under normal circumstances. The patented varipond®-system from Westfalia Separator ensures constant dry substance values in the discharge even when the feed concentrations fluctuate.
varipond® stands for "Variable Pond Depth" in the running machine. In the past, it was necessary to stop and modify decanters used to thicken sludge in order to achieve a constant discharge concentration.
varipond® now makes it possible to make the optimum adjustment simply and reliably when the machine is running. The machine adapts automatically to the changing feed conditions. This is an enormous advantage which ensures optimum thickening, thereby saving a great deal of time and money.
By the use of optical sensors, which operate by the backscatter light principle, the dry substance content of the sludge can be measured online. This achieves an accuracy of ± 0.3% dry substance under operating conditions, allowing reliable and unsupervised operation during the night and at weekends. The constant concentration means that the design of the digestion tower can be optimised and it can be operated economically.
The sludge digests more efficiently and the quality is enhanced.
Regardless how thick and fast, varipond® will not desert you. All decanters with a throughput up to 350m3/h can now be equipped with varipond®.

Thickening of surplus activated sludge
