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Technology - A Novel Reusable Arsenic-Selective Material In Use In Indian Villages

Arup K. SenGupta

In Bangladesh and India, drinking water drawn from underground sources has been responsible for widespread arsenic poisoning affecting over 80 million people. A novel polymer-based hybrid arsenic selective adsorbent (HAIX), originally developed in Lehigh University, Pennsylvania, is currently in use in a village (Ashoknagar) in N. 24 Parganas, West Bengal to provide arsenic-free water  to three hundred (300) families who do not have any other source of reliable drinking water.

The newly synthesized material is essentially an ion exchanging polymer within which the nanoscale iron oxide particles have been dispersed using a chemical-thermal technique developed at Lehigh University. The effort was part of an ongoing collaborative project between Lehigh University in PA, USA and Bengal Engineering College in Howrah, West Bengal. The project is partially funded by the Water For People (WFP) in Denver, Colorado. The concentration of arsenic in the groundwater in the village is over 100 parts per billion. Arsenic concentration in the treated water is consistently less than 10 parts per billion in the well-head treatment unit although the current Indian standard requires 50 parts per billion. The arsenic-selective material, ArsenX, is very durable, mechanically strong and now commercially available through a licensee agreement between Lehigh University and SolmeteX Co., MA (www.solmetex.com). The material is amenable to efficient regeneration and can be reused for tens of cycles.

Several metal oxide nanoparticles offer high sorption affinity toward toxic arsenic compounds present in contaminated groundwater in Indian subcontinent. However, these metal oxide particles are mechanically weak and not durable. On the contrary, polymeric ion exchangers are mechanically strong and very robust but have poor sorption affinity for arsenic compounds. At Lehigh University, hybrid particles have been prepared by dispersing iron oxide nanoparticles within polymer beads containing appropriate ion exchange properties. These hybrid particles (HAIX) are spherical, extremely durable and highly arsenic selective. They are also amenable to regeneration and reuse for tens of cycles with life expectancy of over ten years. Besides being in use in two villages in West Bengal, the HAIX material is undergoing field trials in California, New Mexico, Arizona and New Hampshire for application in North America.

The hybrid adsorbent material (HAIX) is capable of removing both arsenic(V) and arsenic(III)  simultaneously. The well-head arsenic removal system is operationally simple and does not require any electricity or addition of chemicals. Villagers are responsible for day to day operation of the unit through a villagersí committee and each family contributes 30 US cents (10 Indian Rupees.) for the upkeep and regeneration of the unit. More pertinent information is available in http://www.lehigh.edu/~aks0/aks0.html

(Arup K. SenGupta is P. C. Rossin Professor and Chairperson of Department of Civil & Environmental Engineering at Lehigh University. He can be reached at 610-758-3534. )

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