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A simpler and less expensive form of arsenic removal is known as the Sono arsenic filter, using three pitchers containing cast iron turnings and sand in the first pitcher and wood activated carbon and sand in the second.<ref>{{PDFlink|[http://www.unu.edu/env/Arsenic/Munir.pdf Evaluation of Performance of Sono 3-Kolshi Filter for Arsenic Removal from Groundwater Using Zero Valent Iron Through Laboratory and Field Studies]|272 [[Kibibyte|KiB]]<!-- application/pdf, 279183 bytes -->}}</ref> Plastic buckets can also be used as filter containers.<ref>{{PDFlink|[http://phys4.harvard.edu/~wilson/arsenic/remediation/SONO/As%20filtration%20pictures.pdf SONO ARSENIC FILTER FROM BANGLADESH - 1]|102 KiB<!-- application/pdf, 105080 bytes -->}} - pictures with descriptions.</ref> It is claimed that thousands of these systems are in use and can last for years while avoiding the toxic waste disposal problem inherent to conventional arsenic removal plants. Although novel, this filter has not been certified by any sanitary standards such as NSF, ANSI, WQA and does not avoid toxic waste disposal similar to any other iron removal process.
In the United States small "under the sink" units have been used to remove arsenic from drinking water. This option is called "point of use" treatment. The most common types of domestic treatment use the technologies of adsorption (using media such as Bayoxide E33, GFH, or titanium dioxide) or [[reverse osmosis]]. [[Ion exchange]] and [[activated alumina]] have been considered but not commonly used.
===Large-scale water treatment===
Some large utilities with multiple water supply wells could shut down those wells with high arsenic concentrations, and produce only from wells or surface water sources that meet the arsenic standard. Other utilities, however, especially small utilities with only a few wells, may have no available water supply that meets the arsenic standard.
'''Coagulation/filtration''' (also known as [[flocculation#Water_treatment|flocculation]]) removes arsenic by [[coprecipitation]] and adsorption using iron coagulants. Coagulation/filtration using [[alum]] is already used by some utilities to remove suspended solids and may be adjusted to remove arsenic. But the problem of this type of filtration system is that it gets clogged very easily, mostly within two to three months. The toxic arsenic sludge are disposed of by concrete stabilization, but there is no guarantee that they won't leach out in future.
'''[[Iron oxide adsorption]]''' filters the water through a granular medium containing ferric oxide. Ferric oxide has a high affinity for adsorbing dissolved metals such as arsenic. The iron oxide medium eventually becomes saturated, and must be replaced. The sludge disposal is a problem here too.
'''[[Activated alumina]]''' is an adsorbent that effectively removes arsenic. Activated alumina columns connected to shallow tube wells in India and Bangladesh have successfully removed both As(III) and As(V) from groundwater for decades. Long-term column performance has been possible through the efforts of community-elected water committees that collect a local water tax for funding operations and maintenance.<ref>{{cite journal|last=SARKAR|first=S|coauthors=GUPTA, A, BISWAS, R, DEB, A, GREENLEAF, J, SENGUPTA, A|title=Well-head arsenic removal units in remote villages of Indian subcontinent: Field results and performance evaluation|journal=Water Research|date=1 May 2005|volume=39|issue=10|pages=2196–2206|doi=10.1016/j.watres.2005.04.002}}</ref> It has also been used to remove undesirably high concentrations of fluoride.
'''[[Ion Exchange]]''' has long been used as a water-softening process, although usually on a single-home basis. Traditional anion exchange is effective in removing As(V), but not As (III), or [[arsenic trioxide]], which doesn't have a net charge. Effective long-term ion exchange removal of arsenic requires a trained operator to maintain the column.
Both '''[[Reverse osmosis]]''' and '''[[electrodialysis]]''' (also called ''electrodialysis reversal'') can remove arsenic with a net ionic charge. (Note that arsenic oxide, As<sub>2</sub>O<sub>3</sub>, is a common form of arsenic in groundwater that is soluble, but has no net charge.) Some utilities presently use one of these methods to reduce [[total dissolved solids]] and therefore improve taste. A problem with both methods is the production of high-salinity waste water, called [[brine]], or concentrate, which then must be disposed of.
'''Subterranean Arsenic Removal (SAR) Technology''' [http://www.insituarsenic.org SAR Technology]
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==External links==
*[http://www.acdis.uiuc.edu/Research/OPs/Moinuddin/MoinuddinOP.pdf ''Drinking Death in Groundwater: Arsenic Contamination as a Threat to Water Security for Bangladesh''], ACDIS Occasional Paper by Mustafa Moinuddin
*[http://www.st-andrews.ac.uk/news/archive/2010/Title,51258,en.html St Andrews Prize for Environment 2010]
*[http://www.en.wikipedia.org/wiki/Arsenic_contamination_of_groundwaterArsenic contamination of groundwater] wikipedia Wikipedia, March 2012
