There are many different methods of filtration, but all aim to attain the separation of two or more materials. This is achieved by some form of interaction between the substance or objects to be removed and the filter. In addition the substance that is to pass through the filter must be a fluid, i.e. a liquid or gas.

Sand Filters
Sand filtration is frequently used and very robust method to remove suspended solids from water. The filtration medium consists of a multiple layer of sand with a variety in size and specific gravity. When the filters are blocked with solids, the flow direction is Reversed ( Backwash ) to clean the filter again.

Gravity Filtration
WETICO provides a wide range of Gravity Sand Filters which are used to remove suspended solids from raw surface water as a final treatment unit before chlorinat0ion. In addition, these filters can be used in wastewater treatment during the final stages and after the biological treatment to provide more polishing to the secondary treatment effluent as tertiary treatment gravity sand filters. (Please refer to our Domestic Wastewater Treatment section for a more detailed explanation of the wastewater treatment process).

WETICO provides design, manufacturing, supply, and installation services for all types of Gravity Sand Filters such as slow gravity and / or rapid gravity. The filters designed based on the demand required by our clients and the design provided by our Environmental Team.

Pressure Filtration
Pressurized filtration is the most common pretreatment method used in of water treatment. The pressurized filtration requires a filter feed pump(s) and a filter vessel(s). The purpose of pressurized filtration is the removal of suspended solids and other contents of water. The operating pressure ranges from 2.5 – 6.0 bar, the size and constituents of the filter depend on its purpose. Mainly two support layers one a top another followed by another smaller grain size supportive layer as well as an active layer. The active layer may be sand for filtration of suspended solids, birm for removal of iron, carbon for removal of chlorine & odor, anthracite for fine filtration, etc…

The design of the filter vessel requires a case study on the application and varies from one to another.

The Silt Density index should be maintained below 3. Proper periodic backwashing insures longer and better operating regimes.