Technology M Solutions Developing a good solution for arsenic
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developed a rapid screening protocol with the aim of protecting the people already relying on otherwise untested technologies. This protocol is already being used to make sure that these technologies do no harm.
Companies whose technologies don’t make it into the top spots have the option of paying for their own verification, adds Boerschke, who is an OCETA employee on loan to ETVAM. “The ETVAM [project] is based on BRAC
Worldwide awareness of the arsenic crisis in Bangladesh has mobilized researchers from across the globe to devise, revise, and revive a wide variety of technologies for removing the toxic heavy metal from drinking water. To ensure that the country enlists the best possible products—ones that are appropriate for use in a developing nation—Bangladesh has developed a unique program in collaboration with the Canadian government. Between 25 and 80 million Bangladeshi citizens drink water that contains enough arsenic to poison them, says Roy Boerschke, program manager for the Environmental Technology Verification Arsenic Mitigation (ETVAM) program, which was jointly developed by the Canadian and Bangladesh governments and began operation this past January. Studies show that 99% of the contaminated wells have between 50 and 500 micrograms of arsenic per liter of water (µg/L), he says. Long-term exposure to elevated levels of arsenic can cause skin cancers, as well as internal cancers (Environ. Sci. Technol. 2001, 35 (13), 286A–291A). More than 100 organizations are touting technological solutions for removing arsenic from Bangladesh’s groundwater-derived drinking water, Boerschke says. ETVAM has developed a process for screening and validating the relative success of these technologies in meeting the Bangladeshi arsenic standard of no more than 50 µg/L. The program is expected to begin evaluating technologies this month. “In general, the proponents of these technologies are very reputable; unfortunately, a limited number [have made claims that are not reliable],” Boerschke says. Because at least 20 technologies are already being deployed in the field, last year the United Kingdom’s Department for International Development (DFID)
The indigenous“three kolshi”method ofremoving arsenic from drinking w ater,w hich requires onlyclaypots,iron filings,and charcoal,isone ofmanymethodsbeing evaluated foritsutility in helping Bangladeshissafeguard theirw atersupplies.
The ETVAM protocol is meant to be a much more thorough complement to that stopgap effort. Over the next year and a half, it will be used to exhaustively evaluate as many as 12 technologies—the ones that are considered the most promising based on preliminary assessments—courtesy of the Canadian International Development Agency, which has pledged to foot the bill for this first round of testing. The testing protocol is being written so as to allow Bangladesh to use it for future testing efforts, stresses Ed Mallett, president and chief executive officer of the Ontario Centre for Environmental Technology Advancement (OCETA), one of the organizations that contributed to the technology verification program.
ENVIRONMENTAL SCIENCE & TECHNOLOGY / OCTOBER 1, 2001
sound scientific principles and ... those involved in its development have a comprehensive understanding of the scientific rigor and statistical robustness required for a project of this nature,” says David Sutherland, of WS Atkins, a firm that aided the DFID’s assessment of arsenic removal technologies in Bangladesh. For an arsenic-removal technology to be effective in Bangladesh, social and fiscal issues, as well as technological performance, need to be taken into consideration, Boerschke says. His organization’s testing protocol was developed with input from more than 40 international health and development agencies and nongovernmental organizations, including DFID, the World Bank, the Swiss © 2001 American Chemical Society
Development Corporation, and the World Health Organization. “Water collection is primarily undertaken by women, often girls under 10 years old,” he explains, noting that most families collect water individually, although there are some small community-based systems. This means that technologies get bonus points for being lightweight, easy to use, and inexpensive. There are five main approaches that fit Bangladesh’s requirements, according to Boerschke: coagulation/sedimentation, filtration, adsorption, reverse osmosis, and ion exchange. The presence of iron in much of Bangladesh’s groundwater can confound all of these methods, he says. Studies show that the groundwater contains ranges between 0.48 and 15 milligrams of iron per liter of water (mg/L). Some technologies, like the Solar Oxidation and Removal of Arsenic (SORAS) technique developed by researchers at the Swiss Federal Institute for Environmental Science
and Technology, take advantage of the presence of the iron in the water. Stephan Hug and colleagues developed an inexpensive and easy-to-use technology (Environ. Sci. Technol. 2001, 35 (10), 2114−2121) that uses only plastic (polyethylene terephthalate) bottles, citrate from lemons or limes, and sunlight to precipitate out both arsenic and iron. Unfortunately, although the technology worked fine in the laboratory and has a clearly detectable endpoint, testing in Bangladesh revealed that other substances in the water, including dissolved organic carbon, silicate, phosphate, and magnesium, precluded the technology from achieving the levels of removal required by the OCETA tests. Boerschke is reluctant to single out any particular technology for commendation at this point, but he stresses that “several very good technologies are being proposed.” He acknowledges that a number of well-known companies and research universities are promoting these
technologies, including Alcan Aluminum Ltd., Apyron Technologies, Inc., and the Stevens Institute of Technology. He also points out that some indigenous technologies show promise, such as the “three kolshi” method, which requires only clay pots, iron filings, and charcoal. OCETA’s verification process requires testers to test each of the technologies undergoing full verification at the Canadian government’s expense at 20−30 different sites throughout Bangladesh, Boerschke says. The technologies’ performance will also be evaluated in all seasons, including the spring droughts and the summer monsoons, he says. In the long run, Boerschke says he hopes that the process OCETA has developed will prove useful for coping with arsenic contamination in a number of other developing nations where it appears to be a potential problem, including India’s West Bengal region, Vietnam, Cambodia, China, Nepal, Argentina, and Eastern Europe. KELLYN S. BETTS
OCTOBER 1, 2001 / ENVIRONMENTAL SCIENCE & TECHNOLOGY
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