Project Description

Non-Chemical Sludge Thickening

  • enviplan® Microflotation as intermediate secondary treatment


The sewage treatment plant Bottrop cleans the waste water of approx. 650,000 inhabitants and a similarly high load of industrial waste water with a total capacity of 1.34 million inhabitant values. In the area served by the purification plant, there are several industrial dischargers in then region of the cities of Bottrop, Bochum, Essen, Gelsenkirchen und Gladbeck. A surplus sludge volume of 1200m³/h has to be thickened for further treatment in 4 digesters.

The enviplan® Microflotation plant operates with the AQUATECTOR® Microfloat® technology and iFloat® self cleaning injectors and valves and is used for the treatment of a partial amount of excess sludge from the biological cleaning level of the purification plant. It absorbs the excess sludge of the nitrification tank of the 2nd or 3rd cascade of the activated sludge tank. In the flotation, the excess sludge is floated with the aid of motive water taken from the outlet of the final settling tank. The motive water is saturated for this purpose in the pressure re-saturation system AQUATECTOR® with compressed air at about 3.5 bar. In the design with 6 flotation lines or 3 pairs of flotation tanks, a flotate removal through band or chain removal device and 6 pressure re-saturation systems AQUATECTOR®, the flotation system presented here functions successfully with an energy requirement of less than 70Wh per m3 of treated excess sludge

Client: Emscher Genossenschaft

Flowrate of Microflotation: 1.200 m³/h

  • Energy Requirement: <50-70 Wh per m³ Sludge treated
  • Sludge Concentration >7%
  • Non-Chemical Operation