ABSTRACT
Solar water disinfection (SODIS) is a simple, effective and inexpensive water treatment procedure suitable for application in developing countries. Microbially contaminated water is filled into transparent polyethylene terephthalate (PET) plastic bottles and exposed to full sunlight for at least 6h. Solar radiation and elevated temperature destroy pathogenic germs efficiently. Recently, concerns have been raised insinuating a health risk by chemicals released from the bottle material polyethylene terephthalate (PET). Whereas the safety of PET for food packaging has been assessed in detail, similar investigations for PET bottles used under conditions of the SODIS treatment were lacking until now. In the present study, the transfer of organic substances from PET to water was investigated under SODIS conditions using used colourless transparent beverage bottles of different origin. The bottles were exposed to sunlight for 17h at a geographical latitude of 47 degrees N. In a general screening of SODIS treated water, only food flavour constituents of previous bottle contents could be identified above a detection limit of 1 microg/L. Quantitative determination of plasticisers di(2-ethylhexyl)adipate (DEHA) and di(2-ethylhexyl)phthalate (DEHP) revealed maximum concentrations of 0.046 and 0.71 microg/L, respectively, being in the same range as levels of these plasticisers reported in studies on commercial bottled water. Generally, only minor differences in plasticiser concentrations could be observed in different experimental setups. The most decisive factor was the country of origin of bottles, while the impact of storage conditions (sunlight exposure and temperature) was less distinct. Toxicological risk assessment of maximum concentrations revealed a minimum safety factor of 8.5 and a negligible carcinogenic risk of 2.8 x 10(-7) for the more critical DEHP. This data demonstrate that the SODIS procedure is safe with respect to human exposure to DEHA and DEHP.
Subject(s)
Disinfection/methods , Equipment Reuse/standards , Health Status Indicators , Plasticizers/analysis , Sunlight/adverse effects , Water Supply/standards , Beverages , Honduras , Humans , Nepal , Plasticizers/toxicity , Polyethylene Terephthalates/analysis , SwitzerlandABSTRACT
In this research project, we studied factors that presumably affect the incidence of diarrhoea among young children in urban slums in developing countries: consumption of safe drinks, hygiene behaviour, cleanliness of household surroundings and the quality of raw water. Beliefs concerning the causes of diarrhoea were also related to health-improving behaviour, namely the application of the water-treatment method SODIS (solar water disinfection) and hygiene behaviour. We conducted a survey in a shanty town in Nairobi, Kenya. Field workers interviewed 500 households. Analysis with regression models revealed that two out of the four postulated factors were significant: children have a lower risk of contracting diarrhoea when they consume high percentages of safe drinks and live in households with good hygiene. As regards beliefs, we found that biomedical knowledge of children's diarrhoea as well as the perceived social norm for treating water was associated with the use of SODIS and good hygiene.
Subject(s)
Diarrhea/epidemiology , Health Behavior , Hygiene/standards , Water Purification/methods , Child, Preschool , Diarrhea/ethnology , Diarrhea/etiology , Female , Humans , Incidence , Infant , Kenya/epidemiology , Male , Poverty Areas , Regression Analysis , Social Perception , Urban Population , Water Supply/analysisABSTRACT
Se presenta la metodología utilizada en un proyecto de rehabilitación de la etapa de tratamiento previo para una población de 3500 habitantes
Subject(s)
Bolivia , Treatment Plants , Filtration , Water PurificationABSTRACT
En el trabajo se presenta la metodología utilizada en un proyecto de rehabilitación de la etapa de tratamiento previo para una población de 3500 habitantes. La planta de tratamiento constaba inicialmente de filtros lentos y filtros gruesos horizontales, pero debido al alto contenido de turbiedad coloidal de la fuente de provisión no funcionaba adecuadamente. Se realizaron ensayos de laboratorio que permitieron establecer la necesidad de agregar sulfato de aluminio, neutralizando previamente hasta pH=10. Se sugirió transformar los filtros gruesos horizontales en filtros gruesos ascendentes y se construyó una planta piloto que fue operada durante tres meses con excelentes resultados. Se informa sobre los resultados obtenidos durante la operación de la planta piloto, la puesta en marcha de la etapa ya modificada y los resultados obtenidos del monitoreo de las instalaciones durante el verano donde las turbiedades del agua cruda oscilaron alrededor de 1000 UNT y los valores a las sallida de los filtros gruesos siempre fueron menores a 5 UNT
Subject(s)
Bolivia , Water Purification , Filtration , Upflow Filtration , Treatment PlantsABSTRACT
Se presenta la metodología utilizada en un proyecto de rehabilitación de la etapa de tratamiento previo para una población de 3500 habitantes
