Yale Chemists Use Seafood Waste to
Remove Arsenic from Ground Water
The Bulletin of the World Health Organization has called it “the largest mass poisoning of a population in history,” an environmental tragedy “beyond the accidents at Bhopal in 1984 and Chernobyl in 1986.”
It’s also a case of the best of intentions gone awry. In the 1970s the United Nations Children’s Fund (UNICEF), the World Bank and the government of Bangladesh began a major push to transform the delivery of water in that country. Rivers, ponds, mudholes and shallow pit wells, often rife with disease organisms, had been a major source of drinking, cooking and irrigation water in many parts of the nation. Children, especially, suffered high death rates from such maladies as chronic diarrhea, dysentery, typhoid and cholera.
Hundreds of thousands of tube wells were drilled in ensuing decades, and a new era of clean water seemed to have arrived. Infant mortality rates indeed plunged by about half. But by the mid-1990s, health experts, puzzled by growing rates of arsenic poisoning in the region, began to connect the geological, chemical and medical dots. It turns out that arsenic is naturally abundant in ground water aquifers under large parts of the Ganges River delta, in both Bangladesh and the neighboring Indian state of West Bengal.
In 2008 UNICEF reported that more than one-fourth of wells tested in Bangladesh had arsenic levels of more than 50 parts per billion, the nation’s drinking water standard. Even that is five times the level allowed in the United States and recommended by the World Health Organization. In some villages, more than 80 percent of wells were contaminated. In July the British medical journal The Lancet confirmed that as many as 77 million people in Bangladesh alone have been exposed to high levels of arsenic, with grave short- and long-term health consequences that range from severe skin lesions to organ cancer and cardiovascular diseases.
Chemists at the Center for Green Chemistry & Green Engineering at Yale think they’re on the trail of a process that could cheaply, effectively and sustainably help address this problem. The approach relies on titanium dioxide, a nontoxic and commonly used industrial compound (it’s found in white paints and sunscreen) that’s already known as a useful agent in arsenic detoxification and removal.
But the novel approach also relies on green engineering. Uniquely, it uses recycled wastes from the seafood industry to help make the treatment process in the field both less expensive and less technologically complex. And, in what would amount to a major breakthrough, it ultimately aims to turn the recovered arsenic itself into a marketable resource, safely secured away from water supplies. “We want to close that loop,” says Julie Zimmerman, assistant professor of green engineering at Yale and acting director of the center.
Arsenic contamination of drinking water has also been a problem in the developed world, including parts of the United States, and an array of technologies to remove it in centralized water treatment plants is well-established. But according to Zimmerman, finding “appropriate technologies for the developing world” has proven challenging because of a host of “economic, social and environmental considerations.”
Indian scientist Dipankar Chakraborti, who conducted pioneering studies on the arsenic problem in his country and Bangladesh, has reported that attempts at filtering contaminated well water with elaborate mechanical filtration systems often fail because they are difficult and expensive to maintain.
“Given (the) huge contamination area,” he asked in a 2004 interview, “how many water treatment plants can you install every year? Can you take these to remote villages? Will your people remain alive that long?”
In a new paper for the journal Water Research, Zimmerman and Sarah Miller, a Yale Ph.D. candidate in environmental engineering, propose a solution that amounts to an end run around some of the more technologically complex approaches to arsenic removal.