Sand Filter

Sand Filter

Sand Filter

is a filtration solution that helps maintain water (water) quality in water facilities and life support systems. Filtration is an essential component of water treatment for swimming pools, water slides, spray platforms, fountains, life support systems, and other bodies of water in aquatic facilities.

is used to remove suspended, floating and sunken materials and particles to keep the water (water) clean with less chemical use. In addition to suspended matter, COD (chemical oxygen), BOD (biochemical oxygen), organically bound nitrogen and phosphate, and undissolved minerals are also removed from wastewater.

How does it work?

It consists of sand layers, so that the larger grains of sand are present in the lower layer acting as a support, and the smallest grains are in the upper layer. Thus the wastewater (water) flows vertically through a thin layer of sand and/or gravel, and the particles are then removed by adsorption or physical encapsulation.

The work of the sand filter can be divided into two functions:

Surface filtration, through which particles collect on top of the filter layer. Together, these particles form a large porous mass, capable of collecting new particles in a very efficient manner.

Depth filtration, through which smaller, difficult-to-collect particles collect and bind to sand particles through adsorption.

The dirt generated by surface filtration during back rinse is easier to remove than the dirt from deep filtration. To reduce particulate build-up on the filter, an initial sedimentation step is performed for heavily loaded wastewater (lots of suspended and sinkable matter), which helps to avoid frequent filter re-rinsing.

Benefits of a sand filter

It can be said that the main benefit of a sand filter is that it is a simple system that can be used to get great returns. Therefore, sand filters are used in various sectors and processes, where far-reaching removal of suspended matter from water (water) or wastewater (wastewater) is required.

Another benefit is that the sand filter can be placed in different stages of water (water) management: as a pre-treatment, as a side-stream filtration, or as a polishing filter. A sand filter often provides a liquid flow with the possibility of reuse.

Here are some examples of sand filter uses:

Iron removal from ground water using aeration and sand filtration.

Final purification of wastewater, follow-up of mineral deposition and sedimentation to remove residual traces of mineral-based sludge.

Final purification of waste water from the production of iron, steel and non-ferrous alloys. Sand filtration can be preceded by processes such as sedimentation/ sedimentation, coagulation/ flocculation/ sedimentation and flotation.

Purification of waste water (water) containing sand-rock particles and paint particles, for example in shipyards.

Also used as final purification (or before activated carbon filtration) to allow reuse.

Slow sand filters are also used in greenhouse gardening (gardening that reduces greenhouse gas emissions and stimulates soil and plants to absorb carbon dioxide in order to help reduce global warming) so that it acts as a wastewater disinfectant.


Despite its benefits, sand filter filtration sometimes requires the addition of chemicals to improve filter yield.

One of the disadvantages of sand filtration is the rinse water that forms when cleaning the sand filter. This water (water) is highly polluted and must be treated and disposed of.

Neglecting to backwash the sand filter regularly and correctly may cause channels to appear inside the sand filter, which will cause the sand inside to become stony and thus increase the problem of clogging of the sand filter.


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