Sand based water filters have been used for over 100 years to treat waste water. They are generally used on a larger scale to treat a water supply for a whole community, and will be custom made. Most units require a constant flow of water to work correctly, and so wouldn’t be suitable for well water treatment.
Sand filtration is a frequently used very robust method to remove suspended solids from water and wastewater. Because they have one layer of filter media, sand filters remove only relatively large solids (normally in the range of 40 micron and larger). The effective size of each granule of sand typically varies from 0.35 mm. – 40 mm. Larger granules yield coarser filtration. Finer granules yield finer filtration.
The filtration medium consists of a multiple layer of sand with a variety in size and specific gravity.
Sand filters are typically used for:
- Irrigation water
- Storm water
- Preperation of cooling water
- Treatment of waste water
- Production of drinking water
- Filtration in swimming pools
- Pre filtration for membrane systems
- Filtration of grey or surface water
- Removal of iron
- Water in fountains and other water features
Sand filters are used for water purification. There are three main types:
- Rapid (gravity) sand filters
- Upflow sand filters
- Slow sand filters
All three methods are used extensively in the water industry throughout the world. The first two require the use of flocculant chemicals to work effectively whilst slow sand filters can produce very high quality water free from pathogens, taste and odour without the need for chemical aids.
Passing flocculated water through a rapid gravity sand filter strains out the floc and the particles trapped within it reducing numbers of bacteria and removing most of the solids. The medium of the filter is sand of varying grades. Where taste and odour may be a problem (organoleptic impacts), the sand filter may include a layer of activated carbon to remove such taste and odour.
Sand filters become clogged with floc after a period in use and they are then backwashed or pressure washed to remove the floc. This backwash water is run into settling tanks so that the floc can settle out and it is then disposed of as waste material. The supernatant water is then run back into the treatment process or disposed off as a waste-water stream. In some countries the sludge may be used as a soil conditioner. Inadequate filter maintenance has been the cause of occasional drinking water contamination.
Sand filters are occasionally used in the treatment of sewage as a final polishing stage (see Sewage treatment). In these filters the sand traps residual suspended material and bacteria and provides a physical matrix for bacterial decomposition of nitrogenous material, including ammonia and nitrates, into nitrogen gas.
When the filters are loaded with particles, the flow direction is reversed and the flow is increased to clean the filter again. This step is called a backwash.
Design Features of Sand Filters:
Sand Filter capacities are sized differently depending on the type of water, suspended solids concentration, oil and grease, COD/ BOD, iron contents. Chemical injection packages, settling tanks, clarifiers, and disinfection units are also available. Automatic or manual operation. All construction you can select of your choice. Mild steel, Stainless steel or Fiberglass.
If your business is in Thailand, Aquacheme will come to your site to do a site survey. In the site survey, we will examine the installation site, the water quality and the intended use for the water. This will give us the information needed to design the proper system and give you a cost estimate, including installation and maintenance.
Aquacheme’s Sand Filter is easy on your budget. We have installed systems for hotels, resorts, industrial processing, and other commercial applications, and we look forward to designing a system to meet your particular needs.
To find out more about how Aquacheme can help you with your special water quality needs, contact Aquacheme for further assistance with all your Sand Filter needs. We will be happy to assist you.
Aquacheme – Your Sand Filters Specialist