Continuous flotation/filtration clarifying plant DEFF

It represents an integration of the modern flotation and filtration plants in a single processing unit that enables additional cleaning of waste water.


The Continued Flotation/Filtration Clarifying Plant is useful where the supply of huge quantities of highly clarified water is to be guaranteed. The possible fields of use are:

  • for clarification of water in closed circuits for reduction of organic pollution and removal of suspended substances
  • for additional cleaning of municipal and industrial wastewater after the biological cleaning (elimination of phosphorus),
  • for treating of potable water from springs that occasionally give slightly turbid water,
  • for elimination of scarcely decomposed organic pollutants when treating drinking water from sources that are rich in substances resulting from decomposition of organic materials that are of natural origin but give the water a bitter taste.

Technology and Operation In the upper part of the flotation tank a rotating device or distributor introduces the mixture of raw and aerated water into the tank and with a spiral scoop removes the floated sludge from the surface. The lower part of the tank is divided in filter bed segments or cells with layers of filter media for supplementary clarifying of water. After the flotation process has been completed the clarified water is drained through the filters at the bottom of the tank . One-layer sand filter or two-layer filter composed of the hydro- anthracite and filter sand are used for this purpose. Depending on the application, a wide variety of filtering media may be used including special filtering materials that bind certain substances. After a certain time of use the filters get clogged and have to be cleaned. The segments are routinely taken off-line for backwashing. The backwashing of filters occurs automaticly and includes the following phases:

  1. preliminary braking up of the filtrating layer with water,
  2. breaking up of the filtrating layer with air,
  3. backwashing of filters with water at different flow speeds.

For these purposes a portion of the clarified water is used and subsequently removed. The cleaned filter segment is put back on line , while the filtrate that is not perfectly clear returns into the cleaning process. . Thus purified water is collected in the tank for clarified water that is usually positioned under the flotation filter.

Results of some tests in industrial plants: After the tertiary cleaning of municipal wastewaters to which approximately 20mg/L of aluminium sulphate and 0,5mg of cationic polyelectrolyte have been added, the value of the residual KPK dropped from 17,5 to 7,5 mg/l, i.e. for 40%. The concentration of phosphorus in the effluent dropped from the average concentration of 9mg/l to 4,3 mg/l, i.e. for approx 50%. It is possible to lower the concentration of the residual phosphorus to less than 1mg/l by using special chemical auxiliary substances The efficiency of removal of solid particles exceeds 98%. The percentage of the floated sludge amounts to 1,5 - 2,5% of the treated water. It contains 3-6g/l of dry substance, mostly composed of parts of cellulose, micro organisms and phosphates.

Ecology english catalogue2.85 MB

Equipment For Ecology

Enoop design and manufactures waste water treatment equipment and systems for industrial and municipal applications. Our equipment, delivering highly efficient technology optimized for various requirements.