Reid Harvey on mon 1 mar 04
Dear Friends and Colleagues,
Here in Kathmandu we are now beginning to put pottery water purifiers
into low income households, several hundred systems over six months. At
a product presentation workship here last week, with participants from
U.N., U.S. and Nepali agencies, it was announced that our purifiers and
systems had passed the necessary tests with flying colors, and are now
ready to go into the communities, where families are highly vulnerable
and effected by waterborne illness. In the communities in question
there is a lot of dysentery, typhoid, etc., because of bacteria
contaminated water. The candle purifiers in question are silver
saturated, the link: http://www.purifier.com.np
But there is a short supply of the imported colloidal silver, used for
saturation upto now. So our one and only bottleneck is a source of
silver. For this reason we want to begin saturating with silver
nitrate, for us a much simpler and cheaper source of silver. *I am
asking clayart friends to pose an opinion.* Can anyone think of
objections to the use of silver nitrate in production of ceramic water
filters? Please respond to me directly, since I cannot receive Clayart
(regretably). Email: pottery@wlink.com.np
Or the best response would be any information that somewhere in the
world someone is prodcuing silver nitrate filters. That would help give
some encouragement to skeptical managers in the areas of water and
health. A few skeptics simply refuse endorsing silver nitrate because
they've never heard of a silver nitrate filter. Of course, to some
extent this viewpoint of skepticism is justified. If no other concern
would be the establishment of standards, amounts of silver, quality
control in general. And there's an issue of worker safety, not
breathing the grog, not breathing nitrate fumes, or creating waste
problems from the factory. But these problems should not extend to
those using the filters.
We know that nitrates should burn off starting at about 500C, and by the
850 to 1050C firing temperature, by the time the kiln is shut off the
nitrates are history. Then silver metal is presumably bonded to the
pottery medium. Of course simple tests needs to periodically be done,
based on random samplings, testing for the presence in the filtered
water of silver, nitrates, not to mention microbiological membrane
filtration.
If anyone on the list would also like to gather opinions I'd be grateful
to hear of this. We need to get these purifiers out to where they can
be helpful. One problem is that professionals in water and health do
not generally have contact with ceramists, so there's a missing link in
the multi disciplinary knowledge base. For example I feel sure that
some of thse ceramists who work with production of water filters would
have have some ideas or knowledge of the use of silver nitrate. My
guess is that producers in industrial countries, the U.S. Europe and
elsewhere, are finding it a lot cheaper to use fine particulate silver,
colloidal silver, etc. So they have little reason to know about silver
nitrate. But in many countries of South Asia, Africa and others among
the southerly, the silver metal and colloidals silver are expensive and
hard to acquire. On the other hand, AgNO3 is simple to produce and
apply. And as our links have indicated many tests have verified that
silver nitrate treated, ceramic filters are highly effective.
Meanwhile community leaders, in the vulnerable areas, are telling us
that many families will find our systems affordable at smaller systems
for US$4.00 and bigger systems at $6.50. While these deliver the same
amount of water, 2.0 liters per hour, the two systems only differ in
size, 8 liter containers and 12 liter containers respectively. If after
some reasonable comment period we find that siver nitrate is considered
okay, then this will translate into cheaper and more effective filters
for the vulnerable.
Responses are welcome.
Cheers,
Reid Harvey
Pottery Water Purifier Project, Nepal
http://www.purifier.com.np
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