For all interested in potable water for situations where piping from a pure
source is not viable, this message is to acquaint you with some new work being
undertaken by the Arsenic Research Group, Bangladesh.

Under the directorship of Dr. Arif Mohiuddin Sikder, ARG is beginning
fabrication of earthenware purifier candles, saturated with a very tiny amount
of silver. Developed in West Africa during 1999/2000, the purifiers are
now being adapted to Bangladeshi resources.

Other than the silver, these consist of two inexpensive materials only: red
firing clay and a fine grained combustible, in this case wheat flour. The intent
is that the purifier system will be sustainable and affordable by the poorest of
the poor.

As earthenware the filter system is similar to one being successfully promoted
by the Nicaraguan NGO, Potters for Peace. Both the PFP and the ARG systerms are
effective at removing 100% of fecal coliforms. Most of these pathogens are
removed by filtration, the remainder being killed by contact with silver through
oligodynamic action.

The PFP and ARG purifiers do differ in size. The Potters for Peace purifier, is
a 'filter bucket,' a filtering element that resembles a flower pot, and contains
six to eight litres of the contaminated water. By contrast the ARG purifier is a
small sized, filter candle, 8 cm diameter by 14 cm high. This is fastened into
the upper reservoir of the two tiered, plastic bucket system.

It has been known for centuries that contact with silver kills fecal coliforms.
But it was not until 1930 that small clusters of silver atoms were dispersed
throughout permeable, ceramic media. That was when the Swiss company, Katadyn,
patented the system. As data in the original patent application indicates, 100%
of the fecal coliforms are killed because the tortuosity of the filter forces
all of the fecal coliforms into intimate contact with the silver. The ARG
purifier uses only about 0.02 gm of silver, so that this metal adds only about
U.S.$0.01 (one cent) to the cost of permeable earthenware in use.

More information is available at the web page of Ceramiques d'Afrique:

http://www.geocities.com/ceramafrique/

(Note that the site is a bit outdated, not yet indicating successful results of
bacteriological challenge tests, conducted some months ago.) Click the link at
the header to see how the purifiers are made.

See also the web site of the Potters for Peace filter page:

http://www.potpaz.org/pfpfilters.htm

Anyone who is interested should feel free to make contact for additional
information.

Sincerely yours,
Reid Harvey,
Ceramic Industrial Design Consultant