The FlowSand-Filter is an upwards flowing filter with continuous filter bed cleaning. In contrast to other filter systems the filtration process is not interrupted for backwashing.


FlowSand-Filter FunctionSandfilter Function

The raw water flows through the inlet pipe (1) and the inlet distributor (2) in the sand filter bed (3). From there it runs through the filter bed from bottom to top being filtrated by the downwards moving filter bed (in countercurrent flow).

sandfilter flowWater flow

Sand flow


The filtered water exits the filter by the overflow edge (4) through the filtrate outlet (5).

The contaminated sand is passed to the calming unit (7) at the top by using an air lift pump (6). From there the sand falls into the sand washer (8), where it is cleaned in countercurrent flow by a partial flow of the filtrate. The cleaned sand falls back onto the surface of the filter bed and serves as a filter medium again.

The sand distributor conus (9) ensures an even distribution of the sand over the whole filter area. The contaminated washing water exits the filter via the washing water outlet (10).

Often it is useful to conduct a coarse cleaning of the wastewater in advance. Depending on the application, e.g. our Lamella Separators are suitable for an upstream sedimentation.


The FlowSand-Filter is available in a container or concrete design.

Container Design
The containers, usually made of steel, are available as single filter or as multiple version, the latter consisting of several modularly structured single filters. Materials: stainless steel AISI 316TI / AISI 304; carbon steel, GRP; PE.

Concrete Design
The concrete design is mainly used with higher flow rates. A filter plant in concrete design consists of one or several filter lines, each one consisting of several filter cells. The number of filter lines depends on the flow rate and on the process conditions.

FlowSand-Filter Concrete Design

The filter cells of a filter line are open among each other and can be isolated linewise. The raw water inlet and filtrate outlet are made via inlet and outlet channel, the rinsing water outlet via pipeline.
Materials for filter components: stainless steel AISI 316TI / AISI 304; carbon steel, GRP; PE.

Fields of Application

  • Drinking water treatment from surface water or well water

  • Industrial water treatment from well water

  • Sinter water treatment in steel industry

  • Cooling water treatment with circuit

  • Industrial wastewater treatment (chemistry, paper)

  • Final filtration in municipal clarification plants

  • Biofiltration, denitrification and nitrification

  • Filtration with phosphate precipitation


  • No interruption of the filtration process due to continuous filter bed cleaning

  • No collection basins for rinsing water, no rinsing pumps, no buffer tanks for sludge water as well as no complex backwash technology necessary

  • High solid load possible

  • Steady filtrate quality

  • No loose filter parts, high lifetime and availability

  • Feeding without pumps in free inflow possible

  • Low energy costs

  • Simple assembly

Leiblein sewage purification – everything's clear!

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