April 18, 2012
Recipe For Safe Drinking Water: Sunlight And Lime Juice
A team of researchers from the Johns Hopkins Bloomberg School of Public Health and the Johns Hopkins School of Medicine, have found an inexpensive and effective way to clean small amounts of drinking water. Just add sunlight and a twist of lime.
The team found that adding lime juice to water that is treated with a solar disinfection method removed detectable levels of harmful bacteria such as Escherichia coli (E. coli) significantly faster than solar disinfection alone.Solar disinfection of water is one of several household water treatment methods to effectively reduce the incidence of diarrheal illness in low-income areas of the world.
One method of using sunlight to disinfect water that is recommended by the United Nations Children´s Fund (UNICEF) is known as SODIS (Solar water Disinfection). The SODIS method requires filling 1 or 2 liter plastic bottles with water and then exposing them to sunlight for at least 6 hours.
“For many countries, access to clean drinking water is still a major concern. Previous studies estimate that globally, half of all hospital beds are occupied by people suffering from a water-related illness,” said Kellogg Schwab, PhD, MS, senior author of the study, director of the Johns Hopkins University Global Water Program and a professor with the Bloomberg School´s Department of Environmental Health Sciences.
“The preliminary results of this study show solar disinfection of water combined with citrus could be effective at greatly reducing E. coli levels in just 30 minutes, a treatment time on par with boiling and other household water treatment methods.”
“In addition, the 30 milliliters of juice per 2 liters of water amounts to about one-half Persian lime per bottle, a quantity that will likely not be prohibitively expensive or create an unpleasant flavor.”
Researchers found significantly lower levels of both E. coli and MS2 bacteriophage following solar disinfection when either lime juice or lime slurry was added to the water compared to solar disinfection alone.
They did find however, that noroviruses were not dramatically reduced using this technique, indicating it is not a perfect solution.
“Many cultures already practice treatment with citrus juice, perhaps indicating that this treatment method will be more appealing to potential SODIS users than other additives such as titanium dioxide or hydrogen peroxide,” suggest the authors of the study.
However, they caution, “additional research should be done to evaluate the use of lemon or other acidic fruits, as Persian limes may be difficult to obtain in certain regions.”
The results are featured in the April 2012 issue of American Journal of Tropical Medicine and Hygiene.