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'''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, As₂O₃, 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.

==References=={{reflist}} ==See also==*{{cite journal| title = Mechanism 1 Smedley PL, Kinniburgh DG (2002). "A review of arsenic release to groundwaterthe source, Bangladesh behaviour and West Bengal | author = Nickson RT, McArthur JM, Ravenscroft P| journal = [[distribution of arsenic in natural waters". Applied Geochemistry]]| year = 2000| volume = 15| issue = 4| pages = 403&ndash;413| 17 (5): 517–568. doi = :10.1016/S0883-2927(9902)0008600018-4}}5.*{{cite journal| title = 2 Mukherjee A., Sengupta M. K., Hossain M. A. (2006). "Arsenic contamination in groundwater: A Review global perspective with emphasis on the Asian scenario". Journal of ArsenicHealth Population and Nutrition 24 (III2) in Groundwater: 142–163.| author = Korte N*3 Chowdhury U. K., Biswas B. EK., Fernando QChowdhury T. R. (2000).| journal = [[Critical Reviews "Groundwater arsenic contamination in Bangladesh and West Bengal, India". Environmental Control]]| year = 1991| volume = 21| issue = 1| pages = 1Health Perspectives (Brogan &ndash;39| #38) 108 (4): 393–397. doi =:10.10802307/10643389109388408 }}3454378. JSTOR 3454378.*{{cite journal4 Jaymie R. Meliker, Arsenic in drinking water and cerebrovascular disease, diabetes mellitus, and kidney disease in Michigan: a standardized mortality ratio analysis Environmental Health Magazine. Volume 2:4. 2007. Accessed 9 Sept. 2008.| doi = 10*5 Ana Navas-Acien, "Arsenic Exposure and Prevalence of Type 2 Diabetes in US Adults," Journal of American Medical Association, v.300, n.7 (August 2008).1590/S0042-96862000000900005| title = Contamination *6 Singh A. K. (2006). "Chemistry of drinking-water by arsenic in Bangladeshgroundwater of Ganges-Brahmaputra river basin". Current Science 91 (5): a public health emergency 599–606.| author = Smith AH*7 David Bradley, Lingas EO"Drinking the water of death", Rahman MThe Guardian, 5 January 1995| journal = [[Bulletin *8 Amit Chatterjee, Dipankar Das, Badal K. Mandal, Tarit Roy Chowdhury, Gautam Samanta and Dipankar Chakraborti (1995). "Arsenic in ground water in six districts of West Bengal, India: the World Health Organization]]biggest arsenic calamity in the world. Part I. Arsenic species in drinking water and urine of the affected people". Analyst 120 (3): 643–651. doi:10.1039/AN9952000643.| year = 2000| volume = 78| issue = *9| pages = 1093&ndash;1103| url = httpDipankar Das, Amit Chatterjee, Badal K. Mandal, Gautam Samanta, Dipankar Chakraborti and Bhabatosh Chanda (1995). "Arsenic in ground water in six districts of West Bengal, India: the biggest arsenic calamity in the world. Part 2. Arsenic concentration in drinking water, hair, nails, urine, skin-scale and liver tissue (biopsy) of the affected people". Analyst 120 (3)://www917–925.scielospdoi:10.org1039/scieloAN9952000917. PMID 7741255.php?script=sci_arttext&pid=S0042-96862000000900005&lng=en&nrm=iso| pmid=11019458*10 New Scientist, Interview: Drinking at the west's toxic well 31 May 2006.| pmc=2560840}} *11 a b The Times of India, 'Use surface water. Stop digging', interview, 26 Sep, 2004.*{{cite journal| title = 12 a b World Health Organization, Arsenic mobility and groundwater extraction in Bangladesh Drinking Water, accessed 5 Feb 2007.| author = Harvey CF*13 P.L. Smedley, D.G. Kinniburgh, D.M.J. Macdonald, H.B. Nicolli, A.J. Barros, Swartz CHJ.O. Tullio, Badruzzaman ABM| journal = [[Science J.M. Pearce, M.S. Alonso "Arsenic associations in sediments from the loess aquifer of La Pampa, Argentina" Applied Geochemistry 20 (journal2005)|Science]]| year = 2002| volume = 298| issue = 5598| pages = 1602&ndash;1606| 989–1016. doi = :10.11261016/sciencej.1076978| pmid = 12446905}} apgeochem.2004.10.005*{{ cite journal| title = Screening 14 Twarakavi, N. K. C., Kaluarachchi, J. J. (2006). "Arsenic in the shallow ground waters of Rice Cultivars conterminous United States: assessment, health risks, and costs for Grain Arsenic Concentration MCL compliance". Journal of American Water Resources Association 42 (2): 275–294. doi:10.1111/j.1752-1688.2006.tb03838.x.*15 Frederick Rubel Jr. and Speciation | journal = American Society Steven W. Hathaway (1985) Pilot Study for removal of Agronomy Proceeding | author = Raghvan T }}arsenic from drinking water at the Fallon, Nevada, Naval Air Station, Environmental Protection Agency, EPA/600/S2-85/094.*{{cite journal| title = 16 M. Taqueer A. Qureshi (1995) Sources of Arsenic contamination in Bangladesh - An overview the Verde River and Salt River Watersheds, Arizona, M.S. thesis, Arizona State University, Tempe.| author = Hossain MF| journal = [[Agriculture Ecosystem & Environment]]| year = 2006| volume = 113| issue = 1-4| pages = 1&ndash;*17 The history of arsenic regulation, Southwest Hydrology, May/June 2002, p.16.| doi = *18 EPA announces arsenic standard for drinking water of 10 parts per billion, EPA press release, 10/31/2001.1016*19 Alison Bohlen (2002) States move forward to meet new arsenic standard, Southwest Hydrology, May/jJune 2002, p.18-19.*20 Megan A.ageeFerguson and others, Lowering the detection limit for arsenic: implications for a future practical quantitation limit, American Water Works Association Journal, Aug.20052007, p.0892-98.034}}

*[http://www.en.wikipedia.org/wiki/Arsenic_contamination_of_groundwaterArsenic contamination of groundwater] wikipedia Wikipedia, March 2012