ProQuest www.csa.com
 
About CSA Products Support & Training News and Events Contact Us
 
RefWorks
  
Discovery Guides Areas
>
>
>
>
>
 
  
e-Journal

 

Arsenic: An Abundant Natural Poison
(Released March 2009)

 
  by Andreas Saldivar & Vicki Soto  

Review

Key Citations

Visual Resources

News & Scholars

Glossary

Editor
 
Water Treatment Options/ Conclusion

Contents

The effectiveness of a treatment depends on a number of factors, including the oxidation state of the arsenic present (arsenate or arsenite), pH, and competing ions. Arsenate, due to its higher charge of +5, is more easily removed from water than arsenite. The oxidation state of arsenite can be altered from +3 to that of arsenate +5 using ozone or chlorination thereby making it easier to remove from the water. The EPA has approved a number of different methods to lower the concentration of arsenic in water. These include coagulation/filtration, adsorptive media, reverse osmosis, ion exchange, and iron oxide filtration. (U.S. Environmental Protection Agency 2007) (U.S. Environmental Protection Agency 2006) (Drinking Water Program, Maine Division of Environmental Health 2005)

Coagulation/Filtration

This method involves adding a coagulant, such as ferric sulfate or ferric chloride, to the contaminated water. The coagulant alters the properties of the suspended or dissolved contaminants causing them to settle so that they can then be filtered out of the water. (U.S. Environmental Protection Agency 2006)

Adsorptive Media

This involves passing the contaminated water through a media that adsorbs the contaminants. For arsenic, the most common media used is activated alumina (aluminum oxide, Al2O3). This process is more effective if the pH of the water is 6. Effectiveness decreases as the pH increases. (U.S. Environmental Protection Agency 2006)

Reverse Osmosis

This is a process in which the water is passed through a membrane with very tiny pores. Small water molecules pass through but larger elements like lead, iron, chromium, and arsenic are trapped. This works for arsenate (arsenic +5) but not for arsenite (arsenic +3). If the contamination is from arsenite, the water must pass through a pre-oxidizing system first to change it to arsenate. Reverse osmosis systems can be small and attached to a single faucet. (U.S. Environmental Protection Agency 2006) (Drinking Water Program, Maine Division of Environmental Health 2005)

diagram of reverse osmosis

Ion Exchange

This system works by passing the contaminated water through a resin bed of chloride ions. The arsenic ions knock the chloride ions out of the resin bed and take their place. When the resin bed is full of arsenic ions it is back washed with water saturated with salt. The trillions of chloride ions overwhelm the arsenic molecules sending them into the back wash water, which is then taken out of the system as waste water. The chloride ions also recharge the resin and the process can begin again. (U.S. Environmental Protection Agency 2006)

DESCRIPTION
Ion Exchange

Iron Oxide Filtration

This works similarly to an ion exchange system with the added benefit of removing not just arsenate but also arsenite. Unlike the ion exchange system, the filters are not recharged but are disposed. It can be used in conjunction with a reverse osmosis system that is not effectively removing arsenate. (Drinking Water Program 2005)

Tests of these systems have shown that they reduce the concentration of arsenic to 5 ppb or less. (U.S. Environmental Protection Agency 2006) The technology chosen is dependent on various factors including volume of water and other contaminants to be removed.

One relatively new method of arsenic removal is filtering the water using granular ferric hydroxide (GFH) an adsorbent. Studies have shown that it is effective on both arsenite and arsenate with 5 to 10 times higher efficiency than activated alumina. Tests show that the adsorbent can treat 40,000 to 60,000 bed volumes of water before exceeding the arsenic limit of 10 µg/L. It leaves a residual waste of 5 to 25g/m3 of water treated. Under normal conditions the arsenic does not leach from the waste. Therefore it can be disposed of as non-hazardous. The system is cost effective, easy to install and does not require constant monitoring. (Pal 2001) In the US, GFH systems have been in use for some water systems since 2003. (Siemens AG 2009)

Conclusion

Arsenic has been and will always be with us. It is found almost everywhere on Earth - in the soil, in the rocks, and in the water. As the world increases its awareness of the danger and as technology makes it easier to control, we will be able to live with this abundant natural poison.

© 2009, ProQuest LLC. All rights reserved.

List of Visuals

References

  1. American Cancer Society. Arsenic 2009. http://www.cancer.org/docroot/PED/content/PED_1_3X_Arsenic.asp?sitearea=PED (accessed February 26, 2009)

  2. Bates, R.L. and Jackson, J.A., eds. Glossary of Geology. Second Edition, Falls Church, VA: American Geological Institute, 1980.

  3. Bentley, R., and T.G. Chasteen. "Arsenic Curiosa and Humanity." The Chemical Educator 7, no. 2 (2002): 51-60.

  4. Bleiwas, D.I. Arsenic and Old Waste. February 22, 2000. http://minerals.usgs.gov/minerals/mflow/d00-0195/ (accessed February 16, 2009).

  5. British Geological Survey. Arsenic contamination of groundwater in Bangladesh Vol. 2 Final Report. British Geological Survey Report WC/00/19, Keyworth: British Geological Survey, 2001.

  6. British Geological Survey. Arsenic Contamination of Groundwater in Bangladesh Volume 1 Summary. BGS Technical Report WC/00/19, Keyworth: British Geological Survey, 2001.

  7. Brooks, W.E. 2007 Minerals Yearbook. Arsenic [Advance Release]. Reston: U.S. Geological Survey, 2008.

  8. Colonial Williamsburg Foundation. Biography of George Wythe. http://www.history.org/Almanack/people/bios/biowythe.cfm (accessed February 16, 2009).

  9. Drinking Water Program, Maine Division of Environmental Health. Arsenic Treatment. 2005. http://www.maine.gov/dhhs/eng/water/Templates/PrivateWells/arsenictreatment.htm (accessed February 18, 2009).

  10. Focazio, M.J. , and A.H., Watkins, S.A., Helsel, D.R. and Horn, M.A. Welch. A Retrospective Analysis on the Occurrence of Arsenic in Ground-Water Resources of the United States and Limitations in Drinking-Water-Supply Characterizations. Water-Resources Investigations Report 99-4279, Reston: U.S. Geological Survey, 2000.

  11. Hinkle, S.R., and D.L. Poltte. Arsenic in Ground Water of the Willamette Basin, Oregon. Water-Resources Investigation Report 98-4205, Portland: U.S. Geological Survey, 1999.

  12. Howard, H. Houses of the Founding Fathers. New York: Artisan, 2007.

  13. ISSI Consulting Group, et al. Arsenic Occurrence in Public Drinking Water Supplies. EPA-815-R-00-023, Washington, D.C.: U.S. Environmental Protection Agency, 2000.

  14. Kelly, T.D., G.R. Matos, and et al. "Historical Statistics for Mineral and Material Commodities in the United States - Arsenic." U.S. Geological Survey. January 16, 2009. http://minerals.usgs.gov/ds/2005/140/ (accessed January 16, 2009).

  15. Konefes, J.L., and M.K. McGee. "Old Cemetaries, Arsenic, and Health Safety." Water Industry News. http://www.waterindustry.org/arsenic-3.htm (accessed February 16, 2009).

  16. Mead, M. Nathaniel. "Arsenic: In Search of an Antidote to a Global Poison." Environmental Health Perspectives 113, no. 6 (June 2005): A379-A386.

  17. Murderuk.com. Mary-Ann Cotton. http://www.murderuk.com/poisoners_mary_ann_cotton.html (accessed February 15, 2009).

  18. Pal, B.N. "Granular Ferric Hydroxide for Elimination of Arsenic from Drinking Water." In Technology for Arsenic Removal From Drinking Water, edited by M.F. Ahmed, M.A. Ali and Z. Adeel, 59-68. Dhaka: Ahmed, M. F.; Ali, M. A.; Adeel, Z., 2001.

  19. Robinson, G.R. Jr. , and J.D. Ayotte. "The Influence of Geology and Land Use on Arsenic in Stream Sediments and Ground Waters in New England, USA." Applied Geochemistry 21 (2006): 1482-1497.

  20. Siemens AG. GFH Media Removes Arsenic in Arizona Supply. 2009. http://www.water.siemens.com/en/applications/drinking_water_treatment
    /Pages/gf_cs_Phoenix.aspx
    (access February 27, 2009)

  21. Smith, Allan H. , Elena O. Lingas, and Mahfuzar Rahman. "Contamination of drinking-water by arsenic in Bangladesh: a public health emergency." Bulletin of the World Health Organization 78, no. 9 (2000): 1093-1103.

  22. Smith, Roger. Arsenic: A Murderous History. March 30, 2005. http://www.dartmouth.edu/~toxmetal/TXSHas.shtml (accessed February 16, 2009).

  23. Tiemann, Mary. Arsenic in Drinking Water: Regulatory Developments and Issues. CRS Report for Congress, Washington, D.C.: Congressional Research Service, 2007.

  24. U.S. Department of Health and Human Services, Public Health Service, Atlanta, GA (USA). Agency for Toxic Substances and Disease Registry. Toxicological Profile for Arsenic. Atlanta: ATSDR, 2007.

  25. U.S. Department of Health and Human Services. Agency for Toxic Substances & Disease Registry. Arsenic (As) Toxicity Clinical Evaluation. October 30, 2000. http://www.atsdr.cdc.gov/csem/arsenic/clinical_evaluation.html (accessed January 16, 2009).

  26. U.S. Environmental Protection Agency. Arsenic and Clarifications to Compliance and New Source Monitoring Rule: A Quick Reference Guide. Washington, D.C.: US Environmental Protection Agency, 2001.

  27. -. "Arsenic Treatment Technologies. " U.S. Environmental Protection Agency. January 2007. http://www.epa.gov/etv/pubs/600s07007.pdf (accessed February 18, 2009).

  28. -. Arsenic, inorganic (CASRN 7440-38-2). April 10, 1998. http://www.epa.gov/NCEA/iris/subst/0278.htm (accessed February 15, 2009).

  29. -. Chromated Copper Arsenate (CCA): Alternatives to Chromated Copper Arsenate. May 5, 2008. http://www.epa.gov/oppad001/reregistration/cca/alternativestocca.htm (accessed February 17, 2009).

  30. -. Environmental Technology Verification (ETV) Program Case Studies. EPA-600-R-06-001, Washington, D.C.: U.S. Environmental Protection Agency, 2006.

  31. -. Fact Sheet: Drinking Water Standard for Arsenic. January 2001. http://www.epa.gov/ogwdw/arsenic/regulations_factsheet.html (accessed November 25, 2008).

  32. -. "National Primary Drinking Water Regulations; Arsenic and Clarifications to Compliance and New Source Contaminants Monitoring." Federal Register Environmental Documents (U.S. Environmental Protection Agency) 66, no. 14 (January 2001).

  33. -. Technical Fact Sheet: Final Rule for Arsenic in Drinking Water. January 2001. http://www.epa.gov/safewater/arsenic/regulations_techfactsheet.html (accessed February 21, 2009).

  34. U.S. Geological Survey. Arsenic in Ground-Water Resources of the United States. Fact Sheet - FS-063-00, U.S. Geological Survey, 2000.

  35. UNDP Project Access to Information Programme. National Statistics. http://www.bangladesh.gov.bd/index.php?option=com_content&task=view&id=126 (accessed February 20, 2009).

  36. UNICEF. "Arsenic Mitigation in Bangladesh fact sheet." Bangladesh. http://www.unicef.org/bangladesh/Arsenic.pdf (accessed February 20, 2009).

  37. USHistory.org. George Wythe. July 4, 1995. http://www.ushistory.org/Declaration/signers/wythe.htm (accessed February 16, 2009).

  38. Wikipedia, Valence (Chemistry). February 27, 2009. http://en.wikipedia.org/wiki/Valence_(chemistry). (accessed February 27, 2009).

  39. The World Bank. Environment and Social Unit - South Asia Region. Towards a More Effective Operational Response. Arsenic Contamination of Groundwater in South and East Asian Countries Volume II Technical Report. Environmental Study, The World Bank, 2005.

  40. World Health Organization. Arsenic Contamination in Groundwater Affecting Some Countries in the South-East Asia Region. Regional Committee. 54th Session, World Health Organization, 2001, 10 pp.

  41. -. Water-related diseases. 2001. http://www.who.int/water_sanitation_health/diseases/arsenicosis/en/ (accessed November 28, 2008).

  42. World Health Organization, Geneva (Switzerland). WHO Task Group on Environmental Health Criteria for Arsenic and Arsenic Compounds. Arsenic and Arsenic Compounds. Geneva: World Health Organization, 2001, 272 pp.