Download Appendix C Home Water Treatment The objective of brining usable

Appendix C
Home Water Treatment
The objective of brining usable water into the villages of La Fortuna and Tule requires
that at least some of the water be treated for use as drinking water. This was determined
through the site assessment in January 2006, through water quality tests. The major
concern determined by these tests is the presence of coliform bacteria (Attachment 1).
Several different treatment options were considered both for the distribution pipeline and
at each individual tap.
Filtron Ceramic Filter
The first home treatment option considered was the use of Filtron ceramic filters. These
filters originated in Nicaragua and are currently manufactured in over a dozen different
countries, including several in Central America. The water is treated through the
application of a layer of colloidal silver into the ceramic after it is fired (PFP1).
The ceramic filters are very adaptable to use in La Fortuna. The filters each can hold
seven liters of untreated water that will filter through at between one to two L per hour
(PFP1). This makes the filter easy for the end user. With a suitable receptacle, the filters
are typically delivered with a 20 L plastic bucket, a family can fill the filter late at night
and have enough drinking water for the morning when they would have to refill the filter.
This fits well with the current typical routine of the village, substituting carrying water
with filling the filter, seriously reducing the overall exertion.
The fact that the filters are available locally makes them very beneficial. They will not
be difficult to obtain, and they are inexpensive. According to the Filtron website a filter
costs about ten dollars US at first, and four dollars with every replacement pot.
Unfortunately the Filton filters are ceramic, and therefore very fragile. Handling the
filters also reduces their effectiveness; contact can remove the layer of colloidal silver
(PFP1). The ceramic filters must also be replaced every year, increasing the maintenance
costs of the water system. There may also be problems associated with the use of silver
as a treatment agent. Little is known about the long term health effects that this type of
silver exposure could lead to.
Activated Carbon Filters
The other treatment option explored was the use of activated carbon filters. Activated
carbon is a commonly used filtration medium. They are extremely adept at the removal
of organic compounds.
1
Potters for Peace is an international non-profit agency that has been expanding the use of ceramic water
filters in developing countries since 1998. <http://www.potpaz.org/pfpfilters.htm>
It is also fairly easy to produce activated carbon. Plant matter has to be burned slowly in
absence the of air, and then superheated steam is passed through the material. The
process leaves a mass of carbon with an extremely large surface area, a single gram can
have a surface area of over 1000 square meters (MSU2). This means that a small filter
can still process a large volume of water.
Another advantage to activated carbon filtration is the ability to pressurize the filters.
The major use of AC filters is for controlling taste and odor, as well as removal of
chlorine compounds. There are many models sold in the US that fit onto common
household faucets. It is also possible to put filters directly into a pipeline before a faucet.
By pressurizing the filters we gain two distinct advantages. First, we don’t have to wait
for the water to filter through like with the Filtron. This means that it is very easy for the
end user, all they need to do is turn the tap on. Secondly, we have the entire water
system self-contained, there is no need to keep track of a separate filter, or a risk of
breaking the filter.
There are problems associated with choosing to use an Activated carbon filter though.
Because of the presence of bacteria in the water supply AC might not be able to
adequately filter it out. This can be fixed by adding silver to the filters, but that has not
been proven to be effective yet (PFP1). It is also possible for AC filters to turn into
breeding grounds for bacteria, because of the high concentrations of organic compounds
they adsorb. This can be rectified by changing the filters more regularly, but since
regular changes are already needed this is an economic issue that the village does not
need to deal with, (Attachment 2).
2
“Homewater Treatment Using Activated Carbon” Michigan State University Extension. July 1997.
<http://web1.msue.msu.edu/imp/modwq/wq239201.html>
Attachment 1
Attachment 2
Table 2. A comparison of activated carbon filtration
units. (Consumer Reports, 1990)
----------------------------------------------------Cartridge Chloroform
Brand and Model
Price $
Cost $
Removal %
----------------------------------------------------High-Volume Filters
Ametek CCF-201
158
20(2)
100
Ecowater Water Master
250
33(2)
100
Amway E-9230
276
69
100
Hurley II
375
-100
Filtrate CF 10
85
8
90
Cuno AquaPure AP-CRF
155
15
90
Kinetico MAC
275
32
90
Culligan SuperGard THM
349
37
90
Teledyne Instapure IF-10
50
12
80
Omni UC-2
99
20(2)
80
NSA Bacteriostatic 50C
179
-80
(The following two models were down rated because
they clogged after filtering only 300 gallons.)
Bionaire H20 BT850
199
100
100
Everpure H200
298
90
100
Faucet-Mount Filters
Cuno Purity PPO1105
Teledyne Instapure F-2C
Pollenex WP90K
30
24
22
6
5
5
60
45
30
Pour-Through Filters
Brita
30
8
50
Innova
7
5
45
Glacier Pure
13
5
40
-----------------------------------------------------