'Homegrown' relief for victims of arsenic poisoning in South Asia

December 08, 2003

The World Health Organization calls it the "largest mass poisoning of a population in history."

Halfway around the globe, in a region that is no stranger to misery, 100 million people in eastern India and Bangladesh suffer from skin ulcers, tumors and other debilitating and even fatal consequences of arsenic poisoning.

The crisis, says Arup SenGupta, who grew up in the Indian state of West Bengal, is "the biggest natural calamity of our time." Like many environmental problems in developing countries, he says, it cries out for a homegrown solution.

SenGupta, professor of civil and environmental engineering at Lehigh University, says he has developed such a solution in the form of an inexpensive, simple well-head unit that removes arsenic from water wells.

Since 1997, his system has been installed in more than 100 village drinking wells near the cities of Howrah and Calcutta in West Bengal.

Arsenic levels in the filtered wells have plummeted from toxic rates of 100 to 500 parts per billion, SenGupta says, to well below the 50-ppb maximum permitted by the Indian government. Arsenicosis sufferers have found relief from their symptoms, and reports of new cases have plummeted.

SenGupta will visit West Bengal for a week beginning Dec. 22, and will tour several villages where his system has been installed.

Each of SenGupta's systems is built in India and installed by students and professors from Bengal Engineering College in Howrah for a cost of $1,200 to $1,500. The units last about 15 years, although the arsenic-removing materials must be regenerated once or twice a year, and the arsenic requires safe disposal.

Funds for the projected have been provided by Water For People and other non-profit groups and private foundations.

The systems, which are operated with a hand pump and need no electric power or chemicals, are maintained by villagers with help from Bengal Engineering College. Villagers are also trained to check wells weekly for arsenic levels. SenGupta visits the region once a year to supervise.

Recent history, says SenGupta, suggests that solutions to the environmental problems of developing countries, when imposed "top-down" from outside, can cause as much harm as good.

The residents of Bangladesh and West Bengal once obtained their drinking water from rivers, streams and ponds polluted with human and animal waste. Cholera, typhoid, diarrhea and other water-borne diseases resulted and killed hundreds of thousands of people each year.

In the 1970s, Unicef and other aid agencies helped the government of Bangladesh build tube wells to tap underground aquifers whose water was presumed to be safe for drinking.

It was not until 1994 that toxic levels of arsenic were discovered in those wells, SenGupta says. (Arsenic is not present in the region's surface water, he adds.) The arsenic was not generated by human activity, and scientists have not yet determined its origin.

"We do not know how long the arsenic has been in the groundwater," says SenGupta. "We do not know why we find it in one township and not the next, and why we sometimes find it in one well but not in another well located just 100 meters away."

SenGupta, who has taught and served as a consultant in Turkey, the United Arab Emirates, Japan, Germany and Ecuador, was asked by Water For People to design an arsenic-removal system in 1995. An expert in the removal of trace contaminants, SenGupta holds one U.S. patent for an invention that selectively removes phosphate from water and another for a process that removes aluminum sulfate from sludge and enables it to be reused as a coagulant in a water-treatment plant.

SenGupta worked with John Greenleaf, a graduate student in environmental engineering at Lehigh, to develop a way to "impregnate" tiny, polymeric ion-exchange beads with ferric hydroxide. The iron transmits its affinity for arsenic to the beads. The beads, which are arranged in columns, provide a sturdy mechanism for the fine iron powder, which would otherwise form clumps and clog the column, creating a pressure drop and making removal inefficient or impossible.

The result is a hybrid sorbent that removes arsenic from water.

SenGupta and Greenleaf wrote an article about their method that was included in a book, Environmental Separation of Heavy Metals: Engineered Processes, that was edited by SenGupta and published in 2001.

SenGupta and his students are now developing a new hybrid filtration system that uses a polymer-based material. Called "polymer-supported inorganic nano-particles," it uses the same ion-exchange method as the well-head units already installed in India, but SenGupta hopes it will be more effective than the current method.

SenGupta described his most recent work in this area in June at a Colloids and Surface Science Conference at the Georgia Institute of Technology and in September at an American Chemical Society conference in New York City.

Scientists and engineers from developed countries, SenGupta believes, must work more closely with their counterparts in the developing world.

"Our attempts to solve the environmental woes of the 'developing' countries with solutions from the 'developed' ones have often been unsatisfactory, if not disastrous," he wrote in July 2002 in an editorial in the Journal of the Institution of Chemical Engineers, of which he is international editor.
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Lehigh University

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