What Is a Recirculating Filtration System?
A recirculating filtration system is a system that filters tap water and circulates the filtered water. Recirculating filtration systems are divided into two types according to their function: physical filtration systems and biological purification systems.
Physical filtration systems are used to remove fine particles, hair, fibers, and other foreign substances that are not dissolved in water. Biological purifiers use filter media such as activated carbon as a support, in which microorganisms are grown. This type of system has almost no physical filtration function, but the microorganisms are able to decompose pollutants in the water.
Uses of Recirculating Filtration Systems
Recirculating filtration systems can maintain and purify water quality through physical filtration or biological purification. They are therefore used in places where water quality must be kept constant or where water consumption must be reduced.
Principle of Recirculating Filtration Systems
When water to be filtered is passed through a porous filter material, substances larger than the holes in the filter material are collected, and only substances smaller than the holes are passed through. This is how filtration equipment removes foreign substances from water.
There are three main types of filtration systems: sand filtration, diatomaceous earth filtration, and cartridge filtration.
Sand filtration is a filtration method that uses sand or gravel as the filtering material. Natural sand and anthracite are used, and substances down to several tens of micrometers can be removed. It is widely used because of its various advantages, such as its ability to cope with a certain degree of water quality fluctuation and the stable quality of treated water.
Diatomaceous earth filtration is a filtration method that uses diatomaceous earth as a filter aid. It has the highest removal capacity of the three, but is considered difficult to maintain.
Cartridge filtration is a filtration method that uses cartridge-type filter media. Synthetic fiber or polyester is used as the cartridge material, which can remove substances of 10-15 µm in size. Cartridges are consumables, so running costs are relatively high.