Recipe For Safer Drinking Water? Add Sun, Salt And Lime

Recipe For Safer Drinking Water? Add Sun, Salt And Lime : The Salt : NPR

By Gretchen Cuda Kroen (NPR) Pouring water into clear plastic bottles and placing them in the sun can kill disease causing organisms in about six hours. It’s a simple and cheap method that’s been around forever, and it helps. (Who says sun tea isn’t safe?)

But there’s a hitch – the water has to be clear enough for the sun’s rays to penetrate – and much of the world’s water supply is murky from the clay soils in riverbeds and lake bottoms that mix with the water. Enter the scientists.

“Basically, you need to be able to read a newspaper through it. That means it’s clear enough for the UV radiation to penetrate and kill the pathogens. If you can’t see through it, it just won’t work,” explains Joshua Pierce, associate professor of materials science and engineering at Michigan Tech.

Pierce and his colleagues discovered that by adding a little table salt to this murky water, they could get the particles of clay to stick together and settle to the bottom, making the water clear enough to purify using the solar disinfection method. They also found that the addition of salt works best for certain kinds of clay soils, namely bentonite, and not so well with others. But when they added a little bentonite along with salt to water that contained other types of clay soils, it worked just as well.

via Recipe For Safer Drinking Water? Add Sun, Salt And Lime : The Salt : NPR.

Eliminating 10% of gasoline pollutants would have health benefits

A grant from the Energy Biosciences Institute (EBI) has produced a novel and comprehensive “Life Cycle Impact Assessment” to measure the benefits on human health that might result from a switch to biofuels. Although there are a number of uncertainties that must be addressed for a more accurate picture, these early results show that a biofuel eliminating even 10-percent of current gasoline pollutant emissions would have a substantial impact on human health in this country, especially in urban areas.

For a baseline, they used a 10-percent reduction in gasoline use. In assessing the impact of these emissions on human health they looked at “disability adjusted life years or “DALYs,” which is a combination of two common damage factors in LCIAs – years of life lost due to premature mortality (YLLs) and the equivalent years of life lost due to disability (YLDs). One DALY is equal to one lost year of “healthy” life. To put this into perspective, the total annual disease burden in the United States is about 30 million DALYs.

“In looking at emission impacts on health. we have the capacity to carry out county-level resolution measurements for both direct and indirect emissions,” said McKone in his SIM symposium presentation.

Measured emissions at county-level resolution included direct particulate matter and indirect fine particles (2.5 micrometers in diameter or smaller) produced from emissions of sulfate and nitrite gases, volatile organic compounds and ammonia, plus ozone, toxic air pollutants, emissions to surface and ground water, and emissions to soil.

“We found that for the vehicle operation phase of our LCIA, the annual health damages avoided in the U.S. with 10-percent less gasoline-run motor vehicle emissions ranges from about 5,000 to 20,000 DALY, with most of the damage resulting from primary fine particle emissions,” said McKone. “While county-specific damages range over nine orders of magnitude across all U.S. counties most of the damage, as you would expect, is concentrated in urban populations with the highest impact in the Los Angeles, New York and Chicago regions.”

Large urban regions also suffered disproportionate health damage as a result of benzene emissions at service stations and during the transporting by truck of gasoline to service stations – approximately 930 DALYs.

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