Small Community Scale
Drinking Water Disinfection
(Photo from NASA.org)
The World Health Organization estimates that 1.2 billion people are affected by polluted water worldwide. Furthermore, 15 million children under the age of 5 die each year due to water borne diseases (WHO, 2002). Depending on the region, this problem may be complicated by overpopulation (Earthwatch Radio, 2003), contaminated water sources, poor sanitation infrastructure, lack of hygiene education, or some combination of these causes (WHO, 1996). At any given time perhaps one-half of all peoples in the developing world are suffering from one or more of the six main diseases associated with water supply and sanitation (diarrhoea, ascaris, dracunculiasis, hookworm, schistosomiasis and trachoma)” (WHO, 1996). In addition to affecting people directly through disease, poor health acts as a mechanism to further marginalize people by limiting their ability to work, produce food, and interact socially (Bunge, 2000).
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.
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.
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.
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 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:
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
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.
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.
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).
This site addresses a set of consideration that should be taken into account when making decision about water projects and planning
for their implementation.
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