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Volume 17, Number 4 |
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"Civil and Environmental Engineering at
MIT" |
Sturdy, cheap water filter for Nepal wins World Bank prize
For several years, groups of MIT CEE students in the Masters of Engineering Program (MEng) have studied ways to remove pathogens and/or arsenic from contaminated water through the use of drinking water treatment systems based in houses. Any successful system must be affordable for some of the world's poorest people, easy to construct and operate, and cheap to maintain. Their arsenic-biosand filter (ABF) has just won a major award in the World Bank Development Marketplace Global Competition 2003, held in Washington, DC on Dec. 2-4. After presentations to major international development agencies such as the World Bank, USAID and UNICEF, the MIT team project was chosen as one of 47 winners out of more than 2700 entries from 133 countries. Members of the MIT team are CEE Dept. lecturer Susan Murcott '90 & '92, who is also the principal investigator; lecturer Tommy Ngai '02 (MEng); and Sophie Walewijk, a PhD student at Stanford who joined the 2002-03 MIT Nepal Water Project team during field work in January 2003. Ngai won the First Prize Lemelson International Award at the 2002 IDEAS competition for his invention of the ABF system. For the last three years, they have cooperated closely with two partners in Nepal: the Environment & Public Health Organization (ENPHO) in Kathmandu, Nepal, led by Roshan Shrestha; and Rural Water Supply & Sanitation Support Programme (RWSSSP), in Butwal, Nepal, led by Heimo Ojanen. About 90% of the water supply in the Terai region of southeast Nepal comes from tube wells, and it is often contaminated by pathogens and/or arsenic. Investigations by ENPHO, RWSSSP and MIT found arsenic concentrations up to 100 times above the safe drinking level in more than 20% of wells, afflicting about a half million people. Around 40% of wells are also contaminated with pathogens which cause childhood diarrhea, leading to dehydration, malnutrition, stunted growth, and sometimes death. MIT's arsenic biosand filter can remove arsenic and pathogens simultaneously. Tommy Ngai states, "The ABF has been developed based on five years of research at MIT involving a number of former MEng students, especially Jessie Hurd '01, Nat Paynter '01, Lincoln Lee '01 and Heather Lukacs '02, lab and field work in Nepal, and assistance from our Nepali partners." The filter shell or container is made of either plastic or concrete, and it's a little smaller and narrower than a standard US mailbox. It is filled with gravel, coarse sand, fine sand, and iron nails. Because these materials are readily available even in the most remote regions of Nepal, the filtering system is sustainable in the long term. Villagers can build a filter and do their own maintenance, without having to travel long distances to replenish scarce parts. In September 2002, Ngai traveled to Nepal to set up a pilot study with 15 filters in four villages. ENPHO and RWSSSP have been monitoring the filters for more than a year now. To Ngai's satisfaction, "They found that the technical performance is good. Users like the filter very much because it's durable and offers a permanent solution to their water problem. Unlike other filters, there is nothing to break. People also like the very high flow rates. Other filters usually can produce between 1 to 5 liters of filtered water per hour as the water slowly passes through microscopic pores in clay or other media. However, the ABF can process 15 to 30 liters per hour because water quickly seeps through sand and gravel."
Anywhere from once a month to twice a year, depending on how turbid the water supply is, the ABF filter will gradually clog up and will need to be cleaned. Ngai explains the simple cleaning procedure: wash hands, lift out the iron nails, and stir up the water in the top of the filter to resuspend the dirt. Scoop out the dirty water with a cup, add a few inches of clean water, and repeat the procedure of stirring up and removing the dirt several times. In about 15 minutes, the filter will be clean and the flow rate will return to normal. Because of the local geochemistry, arsenic in rocks gradually leaches into the groundwater, then is drawn up in tube wells. This element is slowly poisoning tens of millions of people from Nepal to Bangladesh, and in other parts of South Asia and elsewhere. As the iron nails in the filter rust, the iron attracts and binds arsenic, pulling it out of the water. Eventually the nails will have to be replaced, but tests so far show that they remove arsenic effectively for over a year at a time. ENPHO has a contract with the Nepal Red Cross Society to provide ABF filters, and they have already distributed 500 units. Although capital costs are high by local standards‹$20 to $25 to produce filters in Kathmandu‹there are almost no maintenance costs aside from occasionally replacing the nails. Therefore, the long-term cost of the ABF is comparable to many other filters on the market. Ngai says, "In addition, we expect the manufacturing cost to drop as we train technicians from each village on filter construction." For the year ending July 2004, RWSSSP has already allocated the funds to distribute over 700 concrete filters, and has trained about 40 technicians from various villages in construction techniques. Each village participating in the program receives two steel molds for making water filters, plus the necessary tools. Residents can then procure their own ABF through these technicians. Since it only takes a moment to recontaminate filtered water through poor hygiene, RWSSSP also run education programs in villages to teach about washing hands, hygiene, and the links between water and health. Most of the MIT team's $115,000 in prize money from the World Bank competition will go to its partners in Nepal for expanding the water filter program. The first phase will target about 25 villages with about 10,000 people. Ngai says, "We will be setting up an arsenic/biosand filter technology center for enhanced research, as well as in-depth training and education of water implementers about the ABF technology. The technology center will be a forum for different partners, besides the three involved now, as well as government officials and other interested partners to coordinate the ABF implementation efforts in Nepal. We will exchange implementation knowledge and provide support for each water implementer. Furthermore, we will be collecting useful information in one central data base such as how many filters have been distributed, and how successful they have been." At the grass roots level, Ngai anticipates an active public education effort in villages. "We will set up health education workshops and filter demonstrations for all villagers, with an emphasis on women's participation. We will also train technicians to build, maintain, and repair the filters. We will periodically evaluate the project, write up results, and publicize the efforts in conferences and journal articles for another form of public education." Following his MEng field work in Nepal in 2002, Ngai has already made several short trips to his distant destination. This time he will go to Nepal around mid-January and remain for up to eight months. He expects that it will be quite different working and living there for so long. "There are many things that I need to do: learn to speak Nepali, try to blend into the culture as much as possible. I want to undergo total immersion so I won't feel like a tourist, but instead feel like a part of the population." Acknowledgements: The team would like
to acknowledge the support of MEng program director Dr. Eric Adams, and the help
of Ede Ijjasz '90 & '94 and Nat Paynter '01 in advising the team about
"Development Marketplace." |
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