Better filtration techniques are there than sand filters now, as they are very cumbersome and output is very less. Compact nano-clay filters which perform longer and are easier to wash and rinse and refit are available. You may visit watsan dot in to see the filters . There are add-ons as well like arsenic removal and fluoride removal as well
Depends upon water quality. Range of 0.15 – 0.35mm, and that the uniformity coefficient should be in the range of 1.5 – 3, although a coefficient of less than 2 is desirable.The homogeneous sand filter has a 0.9–1 m deep bed and typically of 0.85–1.7 mm of sand (effective size 0.9 mm) placed on a 50 mm layer of 4–8 mm or 75 mm of 6.7–13.2 mm gravel. Homogeneous sand of effective size up to 1.3 mm has also been used. Please see attached table.
One caution in using sand in a filter media, the sand must be washed of "fines" that will cause "blinding" before it is delivered and placed into service, particle size depends on use and application and there are media selection charts available online from media vendors.
It depends on the size of the sand, the depth and what you are trying to remove. Use the L/d ratio;
L/d ratio—A dimensionless value that is obtained by dividing the length (depth) of a granular media filter bed by the weighted effective diameter “d” of the filter media. The weighted effective diameter of the media is calculated based on the percentage of the total bed depth contributed by each media layer. eg 750 mm depth and a 0.5 mm sand = L/d1500. In general you want to be > 1200 in your L/d.
What is the water to be used for? Are there any other processes as well as the sand filter. If you have a very turbid water you may wish to consider dual media with light coarser media on the top but this will require a high rate regrade flush at the end of the backwash cycle. Kindly Nigel Heeler
Sand is one of the nest Filter media. Depending on the MICRON, it can block all Suspended Solids right up the "Micron level" permitted (depending on the kind of sand). It also blocks Biological Fouling. All of this depends on the kinds of sands available and selected. The bigger Micron Sands go at the bottom and graduate upwards according to Micron Levels and needs.
The choice of the micron Levels is in the design engineering which is contingent on the Water Analysis and desired results.
All Sands can be "Backwashed"
The use of "Beach Well" has proved very good and effective in Desalination of sea water.
There are many more factors to be considered and applied. I shall be happy reply in person on: etsi412@aol.com
You may think of subsea intake systems found to be an eco-friendly technology. A simple modification in the feed water of the sea/freshwater intake system is foolproof to avoid this problem in near future.
Just bore the seafloor/river bottom and extract the water will provide 100% of this biofouling free feed water.
This has been scientifically proven through our publications and industrial-scale seawater reverse osmosis SWR plants.
Adopting this technology enables to the reduction of climate change impacts like carbon dioxide sequestration and global warming.
As these seawater/freshwaters are having microscopic planktonic forms used to be killed by chlorination or other mechanical/chemical treatment in the process of purification. These planktonic forms involved photosynthesis produce oxygens and utilize carbon dioxide to prepare their food and most of the fishery contributors larval forms also got saved by adopting this technology.
Check this link https://thewaternetwork.com/water-news-post-TFp/C_oWk2-4pV15-YPkODCuvg