DynaSand - Nordic Water

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DynaSand is a world-leading continuous sand filter developed by the Axel Johnson Institute in Sweden in the late 1970s. DynaSand is used to clean and produce water for drinking, industrial processes, waste water recycling and waste water treatment before the water is discharged into a recipient. With thousands of filters installed worldwide for municipal and industrial use, we have the experience and equipment necessary to exceed your expectations.

Product information

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Continuous improvement
The range of DynaSand filters is under constant development and includes the latest developments of sand filters, such as material that is extremely resistant to the abrasions caused by sand that is in constant motion during normal operation. The advanced materials mean less maintenance and prolong equipment life. Additionally, you can optimise the sand cleaning rate (the sand/water ratio) with the help of two adjustable weirs with a specially designed wash box, which minimises losses when backwashing.

Uninterrupted operation
Uninterrupted operation provides several benefits over conventional backwashing sand filters. In conventional sand filters particles are collected in the sand bed with increasing pressure drop as a result, until finally the sand must be cleaned by backwashing before treatment can proceed. The time between backwashes can be very short, which reduces the effective operating time. It was not until the continuous sand filter technology of DynaSand was developed that it was possible to get an optimal solution to the need for continuous water and waste water treatment process while delivering a constant quality of the filtrate even at a high surface load.


DynaSand improves the process

  • no first filtrate – always high-quality clean filtrate

  • simple treatment of wash water, no shock loads

  • handles high levels of suspended particles without requiring pre-treatment

  • low pressure drop

  • low energy consumption

  • low monitoring and maintenance costs

  • no need to stop for backwashing

  • small footprint

DynaSand simplifies the system

  • no need for backwashing pumps

  • no tank for rinsing water

  • no collection tanks for rinsing water

  • no need of automatic valves for backwashing

  • no blowers for purge air

  • no nozzles with risk of clogging the filters

  • only one filter medium

  • system is simple to construct and maintain

  • simple expansion for biological treatment

Examples of industrial applications

  • metalworking

  • wash water recycling

  • process water

  • side stream filtration of cooling water

  • scale residues

  • chemical processes

  • ideal as pre-treatment instead of gravity filters

This is how DynaSand works
The incoming water is led down to the inlet manifold in the filter bottom. Suspended solids are filtered out when the water flows upwards through the filter bed. The filtered water is directed to the drain conduit via the weir in the upper part of the filter. Using compressed air an airlift pump in the centre of the filter draws up sand from the bottom into the sand wash where the particles are separated from the sand. The sand bed moves down continuously. A small portion of the filtrate passes through the sand washer and is used to wash the sand before being discharged as wash water. The clean sand falls onto the filter bed and is re-used. The respective filter is started and adjusted via the pneumatics cabinet supplied with the installation.

Two variants – one method
No matter how big or small your facility, we can adapt DynaSand to your circumstances. Smaller plants typically use standalone DynaSand filters while concrete installations are often used at larger works.

Standalone filter
If you select a standalone DynaSand filter you get a device consisting of a cylindrical tank with a conical bottom and internal filter elements. The filter has flanged connections for inlet, filtrate and wash water. The filter system can consist of one or more filters depending on the desired capacity. If you select multiple filters they are connected to the pipework that distributes the incoming water and drains off filtrate and washing water.

Concrete installation
If you want a facility with high capacity it usually takes the form of filter modules mounted in concrete tanks. The filter cells (each consisting of several filter modules) contain bottom cones in stainless steel or FRP and internal filter sections and have a common sand bed. Your facility can be designed for a virtually unlimited filter area allowing DynaSand to be used in both small and large facilities with very different capacities.


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