- Its high specific gravity allows a unique filter design of its kind.
- In combination with other filter media, higher flows, higher loads and better filtration can be achieved.
- Its high hardness reduces material loss through friction, providing many years of reliable service.
- An excellent support bed for other high-density media.
- Meets the requirements of AWWA Standard B100-96.
It is a non-metallic mineral inert to chemicals that is commonly found in the natural environment. The garnet or garnet has a high specific gravity. Its chemical properties, its hardness and its durability make garnet an ideal abrasive filter medium.
As for multimedia or mixed media filtration, the small size of #30-40 garnet high density grain solves a bigger filtration problem. In a single medium granular filter such as a sand filter, the material will hydraulically sort during the backwash according to the size of the granule, with the smallest going to the top. As the water flows down through the sand, the fine particles at the top of the bed do most of the sediment sifting. The solids agglomerate on the surface, with filtration typically occurring within a few inches of the top.
As the agglomerate forms, the filtration becomes finer and the pressure drop increases exponentially with time. The ideal situation would be to have the large grains in the middle at the top to trap the large solids and a grain size that decreases evenly in the direction of fluid flow, leaving the smaller grains at the bottom for final polishing. . The penetration of solids throughout the bed allows for greater solids storage, longer filter runs and higher filtration percentages. A properly designed multi-media system will maintain its unique granulometry of large grains on top and small grains on the bottom and will provide superior performance even after many backwashes.
This stable condition of large grains over the finest is achieved by using materials of different sizes and specific weights. Garnet with its high specific gravity of 4.0 forms the lowest layer of fine grains and its effective size of 0.3 mm can filter down to a range of 10-20 microns. Sand 30-40 (effective size 0.5 mm) and anthracite (effective size 0.9 mm). Multi-media filtration technology is applicable to both water treatment and sewage treatment. Custom filters with variable filter bed configurations can be designed to meet specific customer requirements. For most municipal and industrial water supply applications, a filter bed composed of a 55% of low density material, a 30% of medium density material, and a 15% of high density material is recommended.
Garnet #8 at 140 lbs / ft is a good choice for support beds when using other high density filtration media, such as high purity Corosex II, as well as new manganese dioxide oxidation media such as Pyrolox o Filox and multimedia or deep bed filters