Small activated alumina units treat tube-well water.
In response to the [arsenic] crisis [in West Bengal, India], Dr. Arun Deb, a member of the Water For People Board of Directors, initiated the organization’s work in [...] in 1996 by supporting arsenic-removal efforts and working to develop arsenic-mitigation technologies appropriate for use in rural villages.
Water For People soon partnered with Bengal Engineering and Science University, which developed domestic and well-head arsenic-removal units using activated alumina.
The in-home domestic units consist of two chambers. The upper chamber houses the pretreated activated alumina and the lower stores treated water. For ease of handling (particularly for media regeneration and restoration), the media is enclosed in an impervious nylon bag with a pervious bottom. The media bags are easily removed for offsite regeneration or restoration.
The wellhead units consist of a stainless steel column that is 12 inches (30.5 centimeters) in diameter and 7.2 feet (2.2 meters) in height. Water flows down through a 51-inch (1.3-m.) layer of activated alumina and an 8-inch-thick (20.3-cm.-thick) bed of gravel. The filter media is replaced or restored every eight to 12 months. One wellhead unit can serve from 200 to 300 families.
Effective, inexpensive removal
These simple technologies are highly effective at removing arsenic, relatively inexpensive (approximately US $2,000 [93,721 rupees] for each wellhead unit, including training) and easy to maintain [and] sustainable.
To date, Water For People has financed the installation of 103 of these units, improving the quality of life for an estimated 20,600 people.
[...] Media regeneration, arsenic disposal
Another important consideration for Water For People is effectively dealing with the captured arsenic in a safe and environmentally sensitive fashion. The activated alumina filter media is regenerated annually and sometimes more frequently depending on the arsenic and iron content of the source water.
With the assistance of Bengal Engineering and Science University, a central regeneration facility has been established north of Kolkata in one of the rural areas most affected by arsenic-contaminated groundwater. The facility is being turned over to a private enterprise that is intended to be self-sustaining.
The regeneration process involves transferring the spent activated alumina to a stainless steel drum that is mounted horizontally on an axis to allow for rotation of the drum.
Source: John Kayser, Water Technology Magazine, September 2008