Fashioning relief for Indian villagers who suffer from arsenic-tainted water

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 symptoms of arsenic poisoning caused by drinking contaminated groundwater.

The crisis, says Arup SenGupta, who grew up in the east Indian state of West Bengal, is “the biggest natural calamity of our time.” And like many environmental problems in developing countries, he says, this one cries out for a homegrown solution.

SenGupta, professor and chair of the civil and environmental engineering department at Lehigh, believes he and his students and their counterparts in Bengal Engineering College in India have developed such a solution in the form of a cheap, simple well-head unit that removes arsenic from water wells.

Since 1997, their system has been installed in 25 remote village drinking wells in eastern India, not far from the country’s border with Bangladesh. Over the next two years, engineers hope to install well-head units in 50 additional villages.

Arsenic levels in the treated wells have plummeted from toxic levels of 100 to 500 parts per billion, SenGupta says, to well below the 50-ppb maximum considered safe by health experts and permitted by the Indian government. Each system is built locally with indigenous materials in India and installed by students and professors from Bengal Engineering College in Howrah for a total cost of $1,200 to $1,500. Assembly takes about two to four weeks, and units are expected to last about 15 years, although the arsenic-removing materials need to be regenerated once or twice a year, and the arsenic itself requires safe disposal.

Funds for the project have been provided by a non-profit group called Water For People (WFP) in Denver, Colo., and by other 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, discuss field data and collect samples to analyze in his laboratory at Lehigh.

Political, economic and cultural factors limit the pace at which well-head units can be installed, SenGupta says, but recent history suggests that a “top-down” solution imposed 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 the surface water is still considered unsafe to drink.

In the 1970s, UNICEF and other aid agencies helped the government of Bangladesh build wells to tap underground aquifers whose water was presumed to be safe for drinking. Arsenic, although extremely toxic, does not add color, taste or odor to water. It was not until 1994 that toxic levels of arsenic were confirmed in those wells, SenGupta says. (Arsenic is not present in the region’s surface water, he adds.) Although the arsenic was not generated by human activity, scientists have not yet zeroed in on the mechanism by which it leaches from the soils into the groundwater.

“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 village 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 also taught, lectured and served as a consultant in Turkey, the United Arab Emirates, Japan, Germany and Ecuador, was contacted by a WFP representative after he attended an international conference on arsenic in 1995 in India. 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, an M.S. candidate in environmental engineering at Lehigh who completed a B.S. in civil engineering here in 2000, 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 can remove arsenic from water.

SenGupta and Greenleaf co-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 said the villages where the first well-head units were installed have seen a decrease in the number of new symptoms reported. Doctors say the poisoning cannot be treated but that symptoms can be arrested if a person stops drinking tainted water.  “Seeing people benefit from this is very gratifying,” he says. “There is a sense of fulfillment; that is the wonderful part.”

The larger lesson, SenGupta says, is that scientists and engineers from developed countries 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 invited editorial in the Journal of the Institution of Chemical Engineers (Great Britain), of which he is international editor.

An atmosphere of “mutual trust and respect,” he wrote, would promote a “seamless exchange of information and ideas” and help Third World scientists “find dignity in pursuing a research agenda that is germane to their own needs and well-being.” At the same time, he said, Western universities should require graduate engineering students to take at least one course dealing with environmental issues in the developing world.