PETpla.net Insider 08 / 2014

PET planet insider Vol. 15 No. 08/14 www.petpla.net PET - THE NEXT GENERATION 26 Water disinfection in PET bottles Sunlight + PET = formula for disinfecting water Solar water disinfection - the Sodis method - is a simple procedure to disinfect drinking water. Contaminated water is filled in a transparent PET-bottle and exposed to the sun for 6 hours. During this time, the UV-radiation of the sun kills diarrhoea-causing pathogens such as viruses, bacteria and parasites (Giardia and Cryptosporidium). This makes the conveni- ent method ideal for treating water for drinking in developing countries. A method which, by all accounts, also works at low air and water temperatures. Nepalese woman preparing drinking water using the Sodis method As early as the 1980s, Lebanese scientists found out that sunlight can disinfect water. However, this revolu- tionary discovery did not receive the attention it deserved. Systematic sci- entific studies or adaptations to users’ needs were lacking. So, in the 1990s, the water research institute Eawag, the Swiss Federal Institute of Aquatic Sciences and Technology, decided to investigate the idea and create a safe, simple method that can be used in developing countries. An interdis- ciplinary research team consisting of microbiologists, virologists, engineers and drinking water specialists then worked out a method that only needs PET bottles and sunlight: the Sodis method. To see how effective and how applicable this method was, Eawag ran tests in the laboratory and under field conditions in developing coun- tries. In these tests, the Sodis method was shown to be effective and user- friendly, and also cost-effective. In order to confirm the effective- ness of the technique, it was neces- sary to carry out microbiological tests. The studies investigated the effective-