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Solar disinfection for household water treatment, Africa
Kenya
last update:
3 weeks agoProblems
Lack of acces to quality drinking water
Water in sufficient quantity and good quality is essential for life. However, at the beginning of the year 2000 one-sixth of the world’s population, 1.1 billion people, was without access to improved water supply, and many more lacked access to safe water. No access to good quality drinking water leads to a high risk of water-borne diseases such as diarrhea, cholera, typhoid fever, hepatitis A, amoebic and bacillary dysentery, and other diarrhoeal diseases. Each year 4 billion cases of diarrhoea cause 2.2 million deaths, mostly among children under the age of five. This is equivalent to one child dying every 15 seconds, or 20 jumbo jets crashing every day. These deaths represent approximately 15% of all child deaths under the age of five in developing countries. Apart from the high infant mortality, diarrhea affects numerous children in developing countries in their physical development. Frequent diarrhea is a cause of children’s malnutrition, while malnutrition again increases the likelihood that children to die from an infectious disease such as diarrhea or an acute respiratory illness. Solar Water Disinfection (SODIS) can contribute to improving this precarious situation.
Solutions
Household Water Treatment in Developing Countries: CDC Solar Disinfection (SODIS)
Author: European Commission
Since 1991 EAWAG (The Swiss Federal Institute for Environmental Science and Technology) and SANDEC (EAWAG’s Department of Water and Sanitation in Developing Countries) conducted extensive laboratory and field tests to develop and test the Solar Water Disinfection Process (SODIS) SODIS is a simple, environmentally sustainable, low-cost solution for drinking water treatment at the household level for people consuming microbiologically contaminated raw water. SODIS uses solar energy to destroy pathogenic microorganisms causing waterborne diseases and therewith it improves the quality of drinking water. Pathogenic microorganisms are vulnerable to two effects of sunlight: radiation in the spectrum of UV-A light (wavelength 320-400nm) and heat (increased water temperature). A synergy of these two effects occurs, as their combined effect is much greater than the sum of the single effects. This means that the mortality of the microorganisms increases when they are exposed to both temperature and UV-A light at the same time. SODIS is ideal for disinfecting small quantities of water of low turbidity. Contaminated water is filled into transparent plastic bottles and exposed to full sunlight for six hours. During exposure to the sun, the pathogens are destroyed. If cloudiness is greater than 50%, the plastic bottles need to be exposed for consecutive days in order to produce water-safe for consumption. However, if water temperatures exceed 50°C, one hour of exposure is sufficient to obtain safe drinking water. The treatment efficiency can be improved if the plastic bottles are exposed to sunlight-reflecting surfaces such as aluminum- or corrugated iron sheets. The CBO KWAHO promotes SODIS in the Kibera slums of Nairobi, Kenya. Over 250,000 people are reached by trained promoters using social marketing to disseminate knowledge about SODIS. Research-based information is given out by promoters to potential users, especially when users are skeptical about SODIS. In Latin America, the promotion is channeled through a regional reference center, Fundaçion Sodis. The Fundaçion’s strategy is to build and strengthen a network of partner institutions. The Fundaçion does not implement projects but focuses on training trainers, technical assistance, and lobbying activities. More than 100,000 people are using SODIS in Latin America. In Assam, India, Assam University provided technical and training support for a SODIS promotion project with a local NGO. The dissemination phase targeted 20,000 households based on lessons learned during the pilot phase. An approach involving the active participation of institutions such as village councils, schools, and health centers was adopted to ensure the project is community-owned and sustainable. SODIS has been disseminated to 28 developing countries and is regularly applied by an estimated more than 2 million users.
Gallery
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Timelines
2023
The International Year of Water Cooperation is celebrated, with a focus on promoting cooperation and solidarity among water users and stakeholders. SODIS is recognized as a low-cost and sustainable solution that can empower communities to manage their own water resources and improve their health and well-being
2020
SODIS is promoted as a simple and effective way to ensure safe drinking water at home during the COVID-19 pandemic lockdowns and emergencies.
2018
Eawag launches its first Massive Open Online Course (MOOC) on household water treatment and safe storage, which features SODIS as one of the main topics.
2010
The United Nations Children’s Fund (UNICEF) endorsed SODIS as one of the key interventions to improve access to safe drinking water in schools and communities.
2001
Eawag initiates a program to disseminate the SODIS method through promotion projects in more than 25 low- and middle-income countries.
1996
Eawag published the first SODIS manual, which presents the basic facts and principles of the method.
1991
An interdisciplinary team composed of sanitary engineers, photochemists, bacteriologists, and virologists from EAWAG/ SANDEC embarked on extensive laboratory and field tests to assess the potential of SODIS and to develop an effective, sustainable, and low-cost water treatment method.
1984
Research on solar water disinfection was initiated by Professor Aftim Acra at the American University of Beirut Acra’s work motivated the Integrated Rural Energy Systems Association (INRESA) to launch a network project