Global Dialogue on Nanotechnology and the Poor ... - Nanowerk
Global Dialogue on Nanotechnology and the Poor ... - Nanowerk
Global Dialogue on Nanotechnology and the Poor ... - Nanowerk
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nanotechnology,<br />
water, & development<br />
technology designed to remove cholera bacteria from water.While this<br />
paper is focused <strong>on</strong> <strong>the</strong> applicati<strong>on</strong> of nanotechnology to water<br />
treatment devices, <strong>the</strong> inclusi<strong>on</strong> of <strong>the</strong> Bangladesh case study, which<br />
features a n<strong>on</strong>-nanotechnology approach for water treatment, illustrates<br />
<strong>the</strong> range of issues that must be c<strong>on</strong>sidered when developing projects<br />
for improving access to clean water.These issues are important for<br />
projects that incorporate nanotechnology <strong>and</strong> those that do not.<br />
The case study, which features an approach using sari cloth to filter<br />
cholera bacteria from water, illustrates <strong>the</strong> broad range of ec<strong>on</strong>omic,<br />
social <strong>and</strong> envir<strong>on</strong>mental issues that have to be addressed when<br />
implementing projects in developing countries to improve access<br />
to clean water <strong>and</strong> basic sanitati<strong>on</strong>.This approach, which does not<br />
utilize nanotechnology, also enables comparis<strong>on</strong> to <strong>the</strong> project<br />
featured in <strong>the</strong> South African case study (secti<strong>on</strong> 4) that utilizes a<br />
nanofiltrati<strong>on</strong> membrane.<br />
Cholera <strong>and</strong> o<strong>the</strong>r diarrheal diseases are major killers, especially for<br />
children in developing countries. It is estimated that approximately<br />
5.5 milli<strong>on</strong> cases of cholera are diagnosed annually. In countries such<br />
as Bangladesh, tubewells that tap into groundwater are expected to<br />
provide safe drinking water but studies indicate that <strong>the</strong>y fail to<br />
protect against gastrointestinal diseases.<br />
Boiling water prior to drinking helps kill pathogens, but it is timec<strong>on</strong>suming<br />
<strong>and</strong> may be expensive in countries where <strong>the</strong>re is a<br />
shortage of fuelwood. Bottled water is a suitable alternative in<br />
developed countries but it is too expensive to be a viable opti<strong>on</strong><br />
for people who suffer from waterborne diseases.<br />
Since cholera is dose dependent, filtrati<strong>on</strong> is a practical method for<br />
reducing cholera in areas where people must depend <strong>on</strong> untreated<br />
water.This case study documents an experiment using four layers<br />
of sari cloth as <strong>the</strong> filter, which provides a simple <strong>and</strong> inexpensive<br />
method to remove 99% of cholera bacteria from water.<br />
A community-based study was targeted to underprivileged rural<br />
populati<strong>on</strong>s <strong>and</strong> sought to reduce cholera by directly involving <strong>the</strong><br />
local community. Approximately 45,000 villagers were asked to<br />
participate in <strong>the</strong> trial, in three groups of 15,000 each. 2 A first group<br />
was asked to use <strong>the</strong> sari filter, a sec<strong>on</strong>d group was provided with<br />
nyl<strong>on</strong> filters, <strong>and</strong> a third group was used as a c<strong>on</strong>trol.<br />
Four m<strong>on</strong>ths after <strong>the</strong> system was introduced to <strong>the</strong> villages, 90%<br />
of <strong>the</strong> populati<strong>on</strong> accepted <strong>the</strong> sari filtrati<strong>on</strong> system into <strong>the</strong>ir daily<br />
lives.The field trial indicated that <strong>the</strong>re was a significant reducti<strong>on</strong> in<br />
<strong>the</strong> cases of cholera in <strong>the</strong> groups using <strong>the</strong> nyl<strong>on</strong> <strong>and</strong> sari filtrati<strong>on</strong><br />
systems.The group using <strong>the</strong> sari filtrati<strong>on</strong> method had 48% less<br />
cholera cases than <strong>the</strong> c<strong>on</strong>trol group (i.e., cholera was reduced by<br />
about half).The success of this project, illustrated by <strong>the</strong> data above,<br />
speaks to <strong>the</strong> attenti<strong>on</strong> given by project sp<strong>on</strong>sors to issues such as<br />
cost, ease of use, <strong>and</strong> effectiveness. Projects that involve <strong>the</strong> use of<br />
nanotechnology would need to be sensitive to <strong>the</strong>se issues as well.<br />
It was clear that sari filtrati<strong>on</strong> c<strong>on</strong>tributed to bringing safer water<br />
into houses without any additi<strong>on</strong>al cost to <strong>the</strong> household, resulting<br />
in significant health benefits to people who have very few o<strong>the</strong>r<br />
alternatives.The sari filtrati<strong>on</strong> method was evaluated using a multi<br />
criteria analysis that traces improvements in <strong>the</strong> three sustainable<br />
development indicators: ec<strong>on</strong>omic efficiency (net m<strong>on</strong>etary benefits),<br />
social equity (improved benefits for <strong>the</strong> poor), <strong>and</strong> envir<strong>on</strong>mental<br />
protecti<strong>on</strong> (reduced water polluti<strong>on</strong>). Sari filtrati<strong>on</strong> satisfied <strong>the</strong><br />
ec<strong>on</strong>omic, social, <strong>and</strong> envir<strong>on</strong>mental criteria, while being readily<br />
accessible to <strong>the</strong> public, even after extreme wea<strong>the</strong>r c<strong>on</strong>diti<strong>on</strong>s<br />
such as <strong>the</strong> m<strong>on</strong>so<strong>on</strong>s.The evaluati<strong>on</strong> model is described in more<br />
detail in annex 1, <strong>and</strong> is applicable to o<strong>the</strong>r projects using<br />
technologies to clean water.<br />
The case study authors suggest that simple purificati<strong>on</strong> materials<br />
such as sari cloth, perhaps suitably treated or impregnated with<br />
nanotechnology-based materials, could filter more effectively <strong>and</strong><br />
fur<strong>the</strong>r increase health benefits.<br />
<strong>Nanotechnology</strong> Water Treatment Devices<br />
Given <strong>the</strong> importance of clean water to people in developed <strong>and</strong><br />
developing countries, numerous organizati<strong>on</strong>s are c<strong>on</strong>sidering <strong>the</strong><br />
potential applicati<strong>on</strong> of nanoscience to solve technical challenges<br />
associated with <strong>the</strong> removal of water c<strong>on</strong>taminants.Technology<br />
developers <strong>and</strong> o<strong>the</strong>rs claim that <strong>the</strong>se technologies offer more<br />
effective, efficient, durable, <strong>and</strong> affordable approaches to removing<br />
specific types of pollutants from water. A range of water treatment<br />
devices that incorporate nanotechnology are already <strong>on</strong> <strong>the</strong> market<br />
<strong>and</strong> o<strong>the</strong>rs are in advanced stages of development.These<br />
nanotechnology applicati<strong>on</strong>s include:<br />
<br />
<br />
<br />
<br />
<br />
Nanofiltrati<strong>on</strong> membranes, including desalinati<strong>on</strong> technologies;<br />
Attapulgite clay, zeolite, <strong>and</strong> polymer filters;<br />
Nanocatalysts;<br />
Magnetic nanoparticles; <strong>and</strong><br />
Nanosensors for <strong>the</strong> detecti<strong>on</strong> of c<strong>on</strong>taminants.<br />
Each type of technology, <strong>and</strong> specific examples for each type of<br />
technology, is described in detail in secti<strong>on</strong> 3.<br />
Nanofiltrati<strong>on</strong> <strong>and</strong> Desalinati<strong>on</strong><br />
Nanofiltrati<strong>on</strong> membrane technology is already widely applied for<br />
removal of dissolved salts from salty water, removal of micro pollutants,<br />
water softening, <strong>and</strong> wastewater treatment. Nanofiltrati<strong>on</strong> membranes<br />
selectively reject substances, which enables <strong>the</strong> removal of harmful<br />
pollutants <strong>and</strong> retenti<strong>on</strong> of nutrients present in water that are required<br />
for <strong>the</strong> normal functi<strong>on</strong>ing of <strong>the</strong> body. It is expected that nanotechnology<br />
will c<strong>on</strong>tribute to improvements in membrane technology that will<br />
drive down <strong>the</strong> costs of desalinati<strong>on</strong>, which is currently a significant<br />
impediment to wider adopti<strong>on</strong> of desalinati<strong>on</strong> technology.<br />
Source materials for nanofilters include naturally occurring zeolites<br />
<strong>and</strong> attapulgite clays, which can now be manipulated <strong>on</strong> <strong>the</strong><br />
nanoscale to allow for greater c<strong>on</strong>trol over pore size of filter<br />
2<br />
This project of testing cholera devices was completed in advance of this paper; <strong>the</strong> project was implemented by <strong>the</strong> Internati<strong>on</strong>al Centre for Diarrhoeal Disease Research,<br />
Bangladesh (ICDDR,B) <strong>and</strong> funded by <strong>the</strong> Nati<strong>on</strong>al Institute of Nursing Research of <strong>the</strong> Nati<strong>on</strong>al Institutes of Health, United States, not by <strong>the</strong> GDNP.<br />
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