[Editors] MIT filter cleans Nepalese drinking water

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MIT filter cleans Nepalese drinking water
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For Immediate Release
TUESDAY, MAR. 9, 2004
Contact: Elizabeth A. Thomson, MIT News Office
Phone: 617-258-5402
Email: thomson at mit.edu

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CAMBRIDGE, Mass.--An easy-to-use, inexpensive filter developed by MIT 
researchers for treating contaminated drinking water will be installed 
in 25 Nepalese villages this year, thanks to a $115,000 award from the 
World Bank Development Marketplace Global Competition.

Contaminated drinking water sickens or kills millions of people every 
year, mostly in developing countries. For several years, groups of MIT 
graduate students in the Department of Civil and Environmental 
Engineering (CEE), led by CEE lecturer and research engineer Susan 
Murcott, have studied ways to clean that water.

To be successful, a water filtration system must be affordable for some 
of the world's poorest people, easy to construct and operate and 
inexpensive to maintain. MIT's arsenic-biosand filter (ABF) meets those 
criteria. In addition, it removes not only arsenic but also the 
pathogens that cause childhood diarrhea, which leads to dehydration, 
malnutrition, stunted growth and sometimes death.

With their World Bank funding, the MIT team and Nepali partners "will 
set up an ABF technology center for enhanced research, and provide 
villagers with in-depth training and education about the ABF 
technology," said Tommy Ngai (M.Eng. 2002), a CEE lecturer who has been 
in Nepal for the last month and will be there another seven months to 
meet that goal. His teammates are Murcott and Sophie Walewijk, a Ph.D. 
student at Stanford who joined the MIT Nepal Water Project team a year 
ago.

"We will also be collecting useful information in one central database, 
such as how many filters have been distributed and how successful they 
have been," said Ngai, who earlier won a $5,000 IDEAS International 
Technology Innovation Award from the Lemelson-MIT Program for inventing 
the ABF system.

He wasn't alone in that work, however. "The ABF was developed based on 
five years of research at MIT involving a number of former Masters of 
Engineering Program students, lab and field work in Nepal, and 
assistance from our Nepali partners," Ngai said. Those partners are the 
Environment & Public Health Organization (ENPHO) in Kathmandu led by 
Roshan Shrestha, and the Rural Water Supply & Sanitation Support 
Programme (RWSSSP) in Butwal led by Heimo Ojanen.

The ABF filter shell or container, made of plastic or concrete, stands 
one meter high and is about 0.3 meters in length and width--a little 
taller than a two-drawer filing cabinet. It's filled with gravel, 
coarse sand, fine sand and iron nails. Pathogens are removed from the 
water as it seeps through the sand and gravel; arsenic is removed as 
the iron nails rust, a process that attracts and binds the arsenic.

A pilot study with 15 filters in four villages over more than a year 
has found "that the technical performance is good," said Ngai. "Users 
like the filter very much because it's durable and offers a permanent 
solution to their water problem. Unlike other filters, there's nothing 
to break.

"People also like the very high flow rates. Other filters usually 
produce one to five liters of filtered water per hour as the water 
slowly passes through microscopic pores in clay or other media. The ABF 
can process 15 to 30 liters per hour," Ngai said.

ENPHO has a contract with the Nepal Red Cross Society to provide ABF 
filters, and they have already distributed 500 units. For the year 
ending this July, RWSSSP has already allocated funds to distribute more 
than 700 concrete filters, and has trained about 40 technicians from 
various villages in construction techniques.

Each village in the program receives two steel molds for making water 
filters, plus the necessary tools. Residents can then obtain their own 
ABF through the technicians.

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. "In 
addition, we expect the manufacturing cost to drop as we train 
technicians from each village on filter construction," Ngai said.

Depending on the turbidity (sediment content) of the water supply, the 
ABF filter will clog between once a month and twice a year and need to 
be cleaned. That simple procedure takes about 15 minutes.

Ngai anticipates an active public education effort. "We'll set up 
health education workshops and filter demonstrations for all villagers. 
We'll also periodically evaluate the project, write up results, and 
publicize the efforts in conferences and journal articles for another 
form of public education," he said.

The team received support from M.Eng. program director Eric Adams and 
advice from Ede Ijjasz-Vasquez (S.M. 1990, Ph.D.) and Nat Paynter 
(M.Eng. 2001).

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