Small Community Scale
Drinking Water Disinfection |
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Boiling
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Introduction: (Photo from NASA.org)
Finding a way to provide clean and safe drinking water in affected areas is therefore one necessary step in any effort to improve the quality of life of people in underserved areas and to mitigate the devastating effects of disease on the people of the developing world. For a variety of reasons, methods for clarification and disinfection of drinking water typically used in the developed world are not feasible in the developing world. A number of complicating factors make the gap in resources between the developed and developing world impossible to bridge with the same technologies. However, there are many
treatment technologies that are appropriate and feasible for use in the
developing world. In order for such
technologies to be appropriate, they must be both inexpensive and require
little in the way of external inputs (money, resources, expertise, etc) as
these are typically rare and/or too expensive for small communities in
developing nations. In light of these obstacles,
different treatment technologies may be more or less appropriate in a
specific location depending on resource availability. The following list encompasses a variety
of treatment options requiring a minimum of resources for initiation and
maintenance. Based on the preliminary
information associated with each technology, choose the appropriate
technology for you!!
Photo from Sodis.ch Boiling: Contributes
to deforestation and air pollution.
Only consider if no other technology is appropriate. Otherwise, it is
inexpensive, but labor and fuel wood intensive.
Solar Treatment It has long been known that UV light of an approximate
wavelength of 254 nm can disrupt the ability of yeast, viruses, bacteria, and
protozoa to reproduce. By effectively
neutering these organisms in water, it can be made potable at little cost in a
short amount of time. In addition to
the reduction in biological activity, UV light is also effective at
degradation of a number of chemical compounds known to have adverse health
effects (Watersolve International, 2003).
Sterilization can be achieved with complex and expensive UV
systems. However, the very simple UV
treatment schemes described in this section are intended to make water
potable quickly and cheaply, although some biological activity may still be
present (Rolla, 1998). On a large
scale, UV treatment becomes very money, resource and expertise intensive, as
seen across the developed world.
However, for the individual or family, a small amount of water (as
much as can be contained in existing plastic containers) can be made potable
in a short amount of time. (Although
complex and expensive UV treatment technologies are beyond the scope of this
paper, links and references for information and products in this category
will be listed at the end of this section.) If resources and labor are
extremely limited, the plastic bottle method provides a very simple and
effective method for drinking water treatment. Plastic Bottle Method:
Relatively inexpensive and
requires little if any expertise for
design, construction, or maintenance.
Inactivates bacteria and viruses, but is not effective at removing giardia
or chryptosporidium. Requires
a large quantity of sunlight. Will not work when the sun is not shining. With slightly more money and resources,
the solar box or solar pond may be an appropriate technology for drinking
water treatment in your community. Solar Box/Pond:
Slightly more expensive than
the plastic bottle method, but more effective at removing biological
pathogens. Requires labor, plastic
sheeting, insulation material (potentially sticks, leaves, etc.) and the few
skills necessary to assemble these materials. Advanced Solar
Treatment:
Advanced solar treatment schemes
are complex and expensive and are therefore typically beyond the means of
those living and working in the developing world. This topic is thus beyond the scope of this website. However, the following links and
references provide information and resources necessary to design and
construct a more advanced solar treatment scheme. Advanced UV treatment
technologies: The following links provide
information about advanced solar water pasteurization using photovoltaic
cells:
The following link provides
information on all manner of drinking water issues, with special reference to
advanced drinking water treatment technologies:
Filtration:
Most filtration systems are too
expensive and resource intensive for use in the developing world. However, slow sand filtration is one
method requires few inputs relative to more advanced filtration schemes and
can remove most biological pathogens from drinking water Iodine:
With appropriate contact time,
iodine can effectively remove all biological pathogens. In areas where iodine deficiency is a
problem, iodinated drinking water can provide the supplementary iodine
necessary for healthier citizens.
However, there is tentative evidence that iodine may cause long-term
health problems. Health Canada
recommends limiting iodine use to emergencies. This method also requires the money and resources necessary to
continually import iodine that can be expensive in the long term. Iodine also leaves a residual taste that
is unpleasant to the consumer. Chlorine:With substantially less contact
time than iodine, chlorine can effectively inactivate all biological
pathogens. This method also requires
the money and resources necessary to continually import chlorine (bleach,
hypochlorite, etc.) that can be expensive in the long term. Because chlorine is amongst the most
effective treatment technologies known in the developed world, it seems to
hold great promise for use in the developing world. However there are a
number of adverse health effects known to be associated with chlorine
consumption and byproducts of chlorine disinfection. Alternatives should therefore always be
considered. Community Participation, Money, External Inputs
The technologies presented here
are primarily those requiring the smallest amount of money and resources to
initiate and operate and the smallest amount expertise to sustain. Nonetheless, all of these technologies
require some of these things. Boiling
requires wood or other fuel. UV
treatment requires plastic bottles or other materials. Sand filtration requires materials and the
skill to assemble such a device.
Regardless of the technology chosen for a given household or
community, the main contributing factors to the success or failure of the
technology will be education, community outreach and participation. Experience from the relevant literature
indicates that the successful drinking water projects in the developing world
have focused attention beyond technical aspects of the project (FAO,
2003). Reasons for such a phenomenon
are obvious. Involving people in the
process and the understanding of the causes of their problems and exposing them
to appropriate technologies aimed at the eradication of these problems well necessarily
be more successful and sustainable than traditional methods focusing on
implementation of strategies almost in spite of the needs and wants of the
people (Keketso, 2003). These
sometimes elaborate methods, which have excluded native people from the
process of addressing and fixing their problems has proven to fail in the
past and may well account for the relatively poor record of sustainability
for development projects in the past (Keketso, 2003). Links and Resources:
This site addresses a set of
consideration that should be taken into account when making decision about
water projects and planning for their implementation.
Thanks for Visiting Site Constructed and Maintained
by Melanie Barbier and Daniel
Nover Trees in Ag Systems Website Michigan Technological
University 4/2003 |
