by Andrew McFarland

Infant mortality rates are extremely polarized between developed and developing countries, and one of the most important factors affecting infant survival is access to clean water and proper sanitation. Reports done by the World Health Organization point out that 99.8 percent of water, sanitation, and hygiene related deaths occur in developing countries, and that of those deaths approximately 90 percent are children (World Health Organization, 2002). The main cause of is drinking water or eating food contaminated with human waste. Unlike most developed nations, most rural areas of developing nations lack any sort of central waste collection.  Waste is often spread on to crops as a method of fertilization. That practice, in combination with an inability to wash food products creates a perfect environment for infectious and non-infectious diseases to thrive. The problem is worsened in places like Sub-Saharan Africa due to poverty, lack of infrastructure, and widespread corruption of political officials.

Confronted with how to obtain clean water and promote better sanitation practices in developing nations, I looked for treatment methods that were low cost and easy to implement. One of the main problems with achieving adequate water quality and sanitation in the developing world is the lack of access to electricity, so the systems had to be able to operate using natural forces. Two novel ways of disinfecting water and improving sanitation that were explored include SODIS, which uses plastic bottles and the power of the sun to destroy bacteria, and Constructed Wetland Treatment Systems that decompose contaminants using aerobic bacteria aided by plants.

Diarrhoeal diseases are the leading cause of death for children in developing countries (Parashar, Bresee, Glass 2003). One of the easiest ways to check if a water source is contaminated by sewage is to test for the presence of Escherichia coliform bacteria (E. Coli), which is naturally present in the digestive system of all warm blooded mammals and some reptiles. E. Coli play a necessary role in the digestion and processing of food; without them life as we know it would be impossible. However, certain strains of the bacteria can also cause severe diarrhea in immunocompromised individuals like elderly people and children who drink contaminated water or eat contaminated food. In areas where there is limited access to antibiotics and clean drinking water, contracting diarrhea can be a death sentence. Despite its danger, E. Coli is useful as an indicator species because it is relatively easy to test for, and can give a rough estimate of the level of contamination of a particular water source (Edber, Rice, Karlin, Allen, 2000). High levels of E. Coli bacteria would indicate that a water source is heavily contaminated with sewage, and with sewage comes disease. Salmonella typhi which causes typhoid, and Vibrio Cholerae, the bacteria responsible for Cholera are notorious for causing disease and death throughout Africa (Ashbolt, 2004).

SODIS is a small scale simple treatment method that uses sunlight to destroy potentially disease causing bacteria. The process is simple, easy to teach, and inexpensive to implement. The only materials needed for solar disinfection are a clear container, a flat reflective surface, and sunlight. A clear PET plastic bottle is washed using soap and the label is removed to allow for maximum sunlight exposure, the bottle is then filled with the contaminated drinking water, capped, and placed in direct sunlight for at least six hours to kill the bacteria in the water. The disinfected water is then stored in the same bottle that it was originally decontaminated in. Solar disinfection works using a combination of ultraviolet radiation and heat to destroy bacteria and parasites. The ultraviolet radiation breaks down the cell walls of bacteria and parasites and the heat caused by the sun diminishes the cells repair mechanisms (Caslake et al. 2004). The SODIS method has been been studied extensively in the laboratory and in the field by the Royal College of Surgeons in Dublin, Ireland. One particular study that speaks to the effectiveness of SODIS is a field study titled “Solar Disinfection of Drinking Water and Diarrhoea in Maasai Children: A Controlled Field Trial” conducted in 1996 by the Royal College of Surgeons in Dublin. Conroy, Elmore-Meegan, Joyce, McGuigan, and Barnes (1996) studied a group of children aged five to sixteen in Kenya that had a drinking water source contaminated with fecal coliform bacteria. Conroy et al. (1996) distributed plastic water bottles to 206 children and instructed half of the children to place the bottles filled with contaminated water on the roof of their house in the sun for at least 7 hours and asked the other half to keep bottles inside in the shade as a control group. The Royal College scientists then checked back every 2 weeks for 12 weeks to monitor the frequency of serious diarrhea in both the control and the test group. Their data showed that the SODIS solar disinfection method reduced the occurrence of diarrhea by approximately 25% in the test group (Conroy et al., 1996). Some may argue that 25% is not a large enough decrease to advocate the use of solar disinfection as a water treatment method. Water quality problems in developing nations are going to take a lot of resources a very long time to remedy. SODIS is not a magic bullet, but it could be used as part of a multifaceted approach to reduce waterborne diseases in developing nations. It is hard for a society to advance when it is plagued by illness and any reduction in the rate of disease occurrence is a step in the right direction. In addition to drinking water purification, steps can be taken to reduce the incidence of water source contamination by improving sanitation.

Two years ago during my junior year at the University of Massachusetts Amherst, I had the opportunity to travel to Ecuador with one of my professors to participate in the design and building of a Constructed Wetland Treatment System. The system was built for a Woarani tribe that operated a small ecotourism business in the Amazon River Basin. Our journey to the remote location required a five hour motorboat ride and an additional 3 hours paddling in dugout canoes. All of the materials necessary to build the wetland were procured near the site, the only exception was PVC pipe that had been brought in a few weeks earlier in preparation for the build. All of the construction was done by hand, and after three long days, a crew of 8 men had completed the artificial wetland. Earlier this year (2010) I received an update on the system, it was said to be operating smoothly and has required no major repairs since its construction.

Constructed Wetland Treatment Systems could be used to improve sanitation practices in the developing world by providing centralized waste collection, which would reduce the number of waterborne diseases that could contaminate drinking water sources. The system relies on the power of gravity to move waste water though a series of planted filtration beds that use sand, gravel, and PVC distribution and collection pipes. Each system is different and must be built according to the geography of the landscape. Contaminants are removed using physical and chemical processes. The physical processes include sedimentation and filtration and the chemical processes rely on exposure to UV radiation and microbial decomposition of contaminants (Vymazel, 2005). The microbial decomposition of the contaminants is aided by the use of wetland plants. The plants are used to pump oxygen down into the soil so that the microbes can participate in aerobic decomposition, rather than the slower aerobic decomposition. A literature survey done by Jan Vymazal (2005) of the ENKI Institute analyzed the effectiveness of constructed wetland treatment systems to remove biological contaminants by looking at data from 60 different treatment wetlands. Vymazal (2005) used E. Coli and fecal coliforms as an indicator species to measure the overall biological contamination of the water before and after treatment. She found that on average the artificial wetland treatment systems she reviewed were successful at reducing the amount of coliform bacteria present by 90-99% (Vymazal 2005). Although the effluent may not be drinking water quality, it is suitable for use as crop irrigation and is a huge improvement over the unpurified waste water widely used today. As with SODIS, Constructed Wetland Treatment Systems are not an ultimate solution for water contamination in developing nations, but a piece in a much larger plan reduce mortality from waterborne diseases and improve the lives of people living in those parts of the globe.

It is unfortunate that such large disparities exist between the quality of life for people in places like Sub-Saharan Africa and in America. Improving water quality in developing nations is not going to be easy and it is not going to fast. It is going to take a lot of work and the populations in parts of the developing world do not have the money or resources to do it on their own. The global community has to increase it’s role in helping out countries with high rates of poverty, disease, and death. SODIS and Constructed Wetland Treatment Systems are not a permanent solution to water quality issues, however, they are better than little or no treatment at all. Even the slightest reduction in child mortality rates in developing countries would be a step in the right direction.  Every life counts.

References

Ashbolt, N. J. (2004). Microbial contamination of drinking water and disease outcomes in developing regions. Journal of Toxicology, 198(1), 229-238.

Caslake, L. F., Connoly, D. J., Menon, V., Duncanson, C. M., Rojas, R., Tavakoli, J. (2004). Disinfection of contaminated water by using solar irradiation. Journal of Applied Environmental Microbiology, 70(2), 1145-1150.

Conroy, R. M., Meegan-Elmore, M., Joyce, T., McGuigan, K., Barnes, J. (2004). Solar disinfection of drinking water and diarrhoea in Maasai children: a controlled field trial [Electronic version]. The Lancet, 348, 1695-1697.

Edberg, S.C., Rice, E.W., Karlin, R.J., Allen, M.J. (2000). Escherichia coli: the best biological drinking water indicator for public health protection [Electronic version]. Symposium Series (Society for Applied Microbiology), 29, 106S-116S.

Parashar, U. D., Bresee, J.S,. Glass, R. I. (2003) The global burden of diarrhoeal disease in children [Electronic version]. Bulletin of the World Health Organization, 81(4), 236-236 .

Vymazal, J. (2005). Removal of enteric bacteria in constructed treatment wetlands with emergent macrophytes: a review. Journal of Environmental Science and Health, 40(6), 1355.

Quantifying Selected Major Risks to Health (2003a),World Health Organization. 2002. The World Health Report 2002.(Chapter 4). Geneva.