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07-12-2012, 03:11 PM #1
- Join Date
- Jul 2012
Design Recommendations of Sand Filter
Sand filters are widely used for water purification. The three main types of sand filters are rapid or gravity sand filters, up flow sand filters and slow sand filters. The water industry uses all these methods throughout the world. Rapid sand filters and up flow sand filters make use of flocculent chemicals to work effectively while the slow sand filters produce very high quality water free from pathogens, taste and odor without using any chemical aids.
There are a number of design recommendations for these filters that can be followed for best results. Capture volume i.e. to capture the required water quality, preferably in a separate pretreatment sedimentation basin, the facility should be properly sized.
The basin geometry should be taken care of. When the sedimentation basin is full, the water depth should be at least 2 feet and not greater than 10 feet. To indicate when 20% of the basin volume has been lost because of sediment accumulation, a fixed vertical sediment depth marker should be installed in the sedimentation basin.
The sand and gravel configuration is important. The sand filter is constructed with 6 inches of gravel below 18 inches of sand. A permeable geotextile fabric separates the gravel and the sand media. The gravel layer lies on the geotextile fabric. To drain captured flows from the gravel layer 4 inch perforated PVC pipe is used. At least two inches of gravel should cover the top surface of the PVC pipe.
Each builder in Kochi follows these guidelines to achieve best results in his project.