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Water treatment

For:water treatment plants, tertiary stage of WWTP

Basic Description

Filtralite is a new filtering material intended for drinking water treatment, suitable for the open pressure and biological filters.

Main Advantages of Filtralite

Selectable material density
Specific surface properties of the grains
Higher resistance to grain rubbing
Application of lower washing speeds
High sludge capacity
Lower pressure loss
This results in better quality of the treated water, savings in washing water and energy for filter washing
The Mono-Multi bed allows for easy conversion of single-layer filters into two-layer filters without any change to the washing intensities

History and References

Filtralite is a filtering material that was developed upon twenty years of research in Norway. Its application can be seen all around the world. Its application was verified in detail by the renowned institutions and universities as, for example, University College London, Thames Water Research & Development, IWW Rheinisch-Westfalisches Institut für Wasser Mülheim, University of Duisburg-Essen, Safe Drinking Water Foundation Canada, NTNU Norwegian University of Science and Technology Trondheim, University of Rome „La Sapienza“.

  • Filtralite is used in the drinking water treatment technology since 1997
  • The first water treatment application was filtering in the water treatment plant Ivry sur Seine near Paris
  • As a filter bed it has been hitherto used in 58 drinking water treatment plants in Europe, Asia, North America and Africa

Filtralite Material Properties and Advantages

  • It is produced according to the patented procedure from a clay by burning and sintering at 1 200°C
  • Selectable material density - technologically advantageous composition of filter beds
    • Material density in dry condition can be selected in a range of 500 ~ 1 600 kg/m³
    • Grain size can be selected in a range of 0.8 ~ 20 mm
    • Application in the single-layer and two-layer filters
    • Unique double-layer bed of Filtralite Mono-Multi
    • Lower selectable density of the top layer as compared to the conventional materials
    • Lower washing speed
  • Partly porous structure
    • Application both in conventional and biological filters
    • Application in the iron and  manganese removal process
  • Low pressure loss and better distribution of trapped suspension during filtering
    • High sludge capacity (up to 4x higher production of filtrate than in the sand bed)
    • Savings in washing water
  • Specific surface properties of grains - they improve catchment of suspensions from the treated water
  • Higher resistance to rubbing of grains as compared to anthracite or hydroanthracite

Additional Information

Basic information on verification and comparison of Filtralite with other materials are stated, for example, in the publications [1,2].

Model tests performed in the Czech water treatment plants proved excellent properties of the new filtering material even in our conditions [3,4].

ENVI-PUR, s.r.o. provides or will arrange for a consultancy and model verification of use of this new filtering material and it delivers this filtering material all around the Czech Republic and Slovak Republic. Together with the Leopold drainage system the company assures the best technology available in the water treatment filtering worldwide.

Technical Specifications

Basic types of Filtralite and recommended use

Type Dry material density [kg/m³] Prevailing suitability of application
Filtralite NC 0.8 - 1.6 mm 1 000 ~ 1 200 Double-layer filtering, biological filtering
Filtralite NC 1.5 - 2.5 mm 1 000 ~ 1 200 Double-layer filtering, biological filtering
Filtralite MC 0.8 - 1.6 mm 1 300 ~ 1 500 Single-layer or double-layer filtering, biological filtering
Filtralite MC 1.5 - 2.5 mm 1 200 ~ 1 400 Single-layer or double-layer filtering, biological filtering
Filtralite MC 2.5 - 4.0 mm 1 100 ~ 1 300 Biological filtering
Filtralite HC 0.8 - 1.6 mm 1 500 ~ 1 700 Single-layer or double-layer filtering
Filtralite HC 1.5 - 2.5 mm 1 400 ~ 1 600 Single-layer filtering, biological filtering
Filtralite HC 2.5 - 5.0 mm 1 400 ~ 1 600 Biological filtering, nitrification, single-layer filtering


  1. Saltnes, T., Eikebrokk, B. and Ødegaard, H.: Contact filtration of humic waters: performance of an expanded clay aggregate filter (Filtralite) compared to a dual anthracite/sand filter. Wat. Sci. Tech.: Wat. Sup., Vol. 2, No 5-6, s. 17-23, 2002.
  2. Steele, M.E., Chipps, M., Mikol A., Fitzpatrick, C.S.B.: Alternative filter media for potable water treatment. Water Treatment and Supply Conference, Bath, July 2007.
  3. Dolejš P., Štrausová K., Dobiáš P.: Modelové ověření nového filtračního materiálu Filtralite ve dvouvrstvých filtrech. Sborník konference „Pitná voda 2010“, s. 83-88. W&ET Team, Č. Budějovice 2010.
  4. Dolejš P., Štrausová K., Dobiáš P.: Výběr vhodných filtračních materiálů a jejich vliv na provoz filtrů. Sborník konference Voda Zlín 2011, s. 99-104. Moravská vodárenská, Zlín, 2011.