Design of Granular Media Filter

There are different types, related to the design of Granular Media Filter and it can be grouped and identified based on:
  1. Its mode of operation whether it is continuous or semi-continuous.
  2. Type of filter bed whether it is stratified or not stratified
  3. The filter media (sand, activated carbon, garnet or anthracite)
  4. Filter bed depth
  5. Flow rate whether it is constant or variable
  6. Feeding whether by use of pump or just gravitational force
Selection on the best Granular Filter to use in wastewater treatment plant depends on several factors such as the required filtration rate and also whether the infeed wastewater has been properly treated to remove most of the solids during the secondary treatment processes. Obviously when the biological feed load is much less, the type of filter media and requirements can be scaled down in order to save cost and avoid complicating on the operational issues.

Whether the selection of filter bed is towards those stratified or not basically depends on the approach used to do backwashing of the filter. During the washing procedure, if only water is used, this will cause the filter bed to become stratified at the end of the process. Therefore, in certain backwashing techniques whereby both air and water are used together, this will produce an unstratified bed and in order to avoid this, the backwash using only water must be at the end of the procedure.

The filter media can be used in various combinations to produce multiple layer of filter media beds setup. Suitability using different types of filter media in a combined bed will vary depending on the wastewater characteristics. Basically, in order to find out which one is the best, usually a pilot plant can be constructed for this purpose to test it out before making final conclusion. This applies as well towards the depth of the filter bed and basically if the wastewater feed contains high concentration of suspended solids, then a pump should be used to generate the force to push it through the filter. Find out more regarding the application aspect on the use of Granular Media Filter in wastewater treatment facilities.

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