Maria Botha (left) and Liani Broodryk (second from left) of the Ripples for Good team will promote a very basic biotechnology for safer drinking water - the disinfection of water by the sun (SODIS) - on their six-month crusade to raise public awareness around water conservation and safe consumption. Pictured with them is CSIR microbiologist Martella du Preez and their two dogs Dante and Katrin
Travelling unaided by motorbike, bicycle, canoe, donkey cart or on foot, want to inspire ordinary people to become involved and seriously think about how they’re using water.
With the support of CSIR microbiologist Martella du Preez, they will promote a very basic biotechnology for safer drinking water - the disinfection of water by the sun (SODIS).
According to Du Preez, considerable health benefits can be derived, at no cost, from drinking water that has been disinfected by sunlight.
“The method is particularly applicable in African countries where sunlight abounds. At its simplest, ‘batch-process’ solar disinfection involves filling 1 to 2 litre polyethylene terephthalate (PET) plastic bottles with water and leaving them in full sun for six hours.
“The biocidal effect of sunlight is due to optical and thermal processes, and a strong synergistic effect occurs at temperatures exceeding 45 °C. In addition to direct UV-killing, sunlight is absorbed by photosensitisers present in the water that then react with oxygen, producing highly-reactive oxygen molecules such as hydrogen-peroxide and superoxides, which exert a disinfecting effect,” she explains.
The method is effective against infectious bacteria such as Vibrio cholerae, Salmonella typhimurium, Shigella dysenteriae type I, Pseudomonas aeruginosa, Fusarium solani, the trophozoite stage of Acanthamoeba polyphaga and even Cryptosporisium parvum, an intestinal parasite that is very resistant to other types of water disinfection methods, including chlorination.
In a study conducted in three African countries earlier this year, Du Preez and her team found a significant reduction in dairrhoea in younger children when they consistently followed the SODIS guidelines.
Solar disinfection is currently in use by more than 2 million people who rely on it to provide safe drinking water in more than 20 developing countries.
For more information on the SODIS research project, please visit their website at http://www.rcsi.ie/sodis/index.htm. You can follow Ripples for Good’s journey via their blogspot at http://lianig4g.blogspot.com/ and http://www.mariag4g.blogspot.com/.