Removal of Arsenic from Village Drinking Water Supplies in West Bengal
Dr. Arun Deb
Vice President (Retired), Weston Solutions, Inc.
West Chester, Pennsylvania
Introduction and Background
West Bengal, a state in Eastern India is very rich in groundwater and more than 80 percent of its populations tap this source as drinking water. In West Bengal, and in the neighboring nation of Bangladesh, a health crisis of devastating proportions has been quietly unfolding over many years. Much of the groundwater underlying the Upper Deltaic plain between the Bhagirathi River in West Bengal and the Padma River in Bangaladesh has been contaminated by arsenic concentrations exceeding the permissible limit of 0.05 mg/L arsenic concentrations most often ranged from 0.09 to 3.2 mg/L. Arsenic occurrence in the regions aquifers has been attributed to geological factors. Arsenic mobilization in the water may have been caused by over withdrawal of groundwater during cultivation. Contaminated water sample analyses have shown that arsenic in the form of arsenite [As(III)] is prevalent. Compared with arsenic in the form of arsenate [As(V)], As(III) is reported to be more mobile and more toxic. The contaminated groundwater constitutes the sole source of drinking water for 12 to15 million people in West Bengal who use hand pumps to draw water from scattered wells. The effects of arsenic accumulation in the human body are well-documented – skin lesions and disorders of the circulatory and nervous system. Among the impacted villagers, clinical manifestations of arsenic poisoning include hyperkeratosis and hyper pigmentation in palms and soles, arsenical dermatitis, skin cancers, as well as gastrointestinal symptoms such as nausea, abdominal pain and diarrhea. Current evidence indicates that symptoms of arsenicosis developed after years of ingestion of arsenic contaminated water. The crisis in West Bengal unfolded over many years, and its solution would demand a commitment of time, expertise and funds.
The World Health Organization (WHO) guideline value for concentration of arsenic in drinking water is 0.01 parts per million (ppm). However, after due consideration of environmental factors, socioeconomic conditions, food habits, etc. 0.05 ppm has been accepted as the Maximum Admissible Concentration (MAC) of arsenic in drinking water by many countries in the world, including India. While arsenic pollution in drinking water has been reported in other countries like Taiwan, Japan, Mexico and the United States, the problem in West Bengal and neighboring Bangladesh seems to be gravest in the context of the area and population affected. To save millions of people from being affected with arsenic toxicity, appropriate and sustainable treatment of contaminated water at village wells is necessary.
In January 1996, Water for People (WFP), a non-profit organization, located at Denver, Colorado, with the objective to help providing safe drinking water to poor people in developing countries, awarded Bengal Engineering College (BEC) a grant of $ 10,000 to conduct a laboratory study to select arsenic-removal technologies appropriate for use in rural villages. The project partners recognized that arsenic removal technology for West Bengal must not only be effective but also relatively simple in terms of operation and maintenance. The environmental engineering laboratory of Civil Engineering Department, Bengal Engineering College conducted laboratory tests to determine the most effective technology for removing arsenic. Locally available activated alumina (AA) proved to have significant capacity for arsenic removal.
Bengal Engineering College working with Lehigh University, Pennsylvania developed domestic and wellhead Arsenic Removal Units. The well-head units are named AMAL Arsenic Filters, after late Dr. Amal Datta, Professor of Civil Engineering of B. E. College and the...
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