Sand Filter

continuous filters

Proven technology with the latest innovations

Dynasand™ by nordic Water is the world’s leading continuous sand filter, initially designed by the Johnson institute in sweden in the late 1970-ies, which allows you to get the most out of your water treatment.

combined with DynaAir, lamella separator and DynaDisc by nordic Water, your water quality can be greatly improved with signifi-cantly reduced operating costs over the entire life time of your investment. With tens of thousands filters installed around the world for municipal and industrial applications, nordic Water has all the experience and equipment needed to exceed your expectations.in 1974 Dr. Hans larsson led a group at the Axel Johnson institute to develop the continuous backwash sand filter. this group was awarded a uspatent for the filter in 1978 and for continuous contact filtration in 1981. Axel Johnson institute became Axel Johnson engineering in 1981 and nordic Water products in 1992. over the course of nordic Water products’ long history and extensive experience the filter has been modified and improved for use in multiple applications, including deni-trification, nitrification, and enhanced phosphorous removal.the uninterrupted mode of operation offers a number of advantages compared to conventional backwash sand filters. in conventional sand filters solids are accumulated in the sand bed progressively increasing the head loss until, finally, the sand must be cleaned by backwashing before treatment can resume. the time between backwashings can indeed be very short, reducing the effective operating time. it is only with the development of the Dynasand by nordic Water continuous sand filtration technique, that the users could benefit from an optimal solution to their needs for a continuous processing of water and waste water which also provides a constant filtrate quality even at high sur-face loads.
tens of thousands Dynasand filters have been installed by nordic Water throughout the world, providing excellent reliability and perfor-mance to their users in a wide variety of applications.

Proven Process

the Dynasand is an up-flow, moving bed filter that is constructed with various media depths for different
applications and configurations. raw water enters near the top and is led to the bottom of the tank by means of a water distributor. suspended solids are filtered out as the raw water flows up through the media bed. As the water reaches the top of the filter, it passes over the effluent weir as filtrate and is discharged. A small portion of the filtrate is diverted through the sand washer and used for cleaning and transferring the waste solids.the Dynasand filter employs a backwash rinse that is performed continually while the tank is processing water. An air lift pump, located at the center of the module draws the media from the bottom of the filter up into the wash box. As the media is released into the wash box, it falls into the sand washer where the filtered solids are separated from the sand. from there, the filtrate carries the solids out as waste (backwash). the washed sand falls down onto the media bed for continued use.each air lift pump is adjusted and regulated by the pneumatic cabinet supplied with the installation.

Advantages :
DynaSand improves the process
• no first filtrate – always clean effluent of a high quality
• no shock loads on the wash water treatment system
• High suspended solids without need for pre-treat-ment
• low head loss
• low energy consumption
• low supervision and maintenance costs
• no interruption of the operation for backwashing
• small footprint
DynaSand simplifies the system
• no need for backwash pumps
• no wash water storage tanks
• no wash water collecting tanks
• no need for backwash automation
• no air scour blower
• no clogging filter bottom nozzles
• single media filter bed
• the system is easy to construct and easy to maintain
• easy retrofitting for biological treatment
Examples of Industrial Applications
• metal finishing
• Backwash water recovery
• process water
• cooling tower blowdown/side stream filtration
• steel mill scale
• chemical processing
• ideal for pretreatment in lieu of gravity filters