Posted on 03/03/2007 6:54:16 PM PST by neverdem
| Web address: http://www.sciencedaily.com/releases/2007/02/070228082232.htm |
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Science Daily — University of Delaware researchers have developed an inexpensive, nonchlorine-based technology that can remove harmful microorganisms, including viruses, from drinking water.
UD's patented technology, developed jointly by researchers in the College of Agriculture and Natural Resources and the College of Engineering, incorporates highly reactive iron in the filtering process to deliver a chemical “knock-out punch” to a host of notorious pathogens, from E. coli to rotavirus.
The new technology could dramatically improve the safety of drinking water around the globe, particularly in developing countries. According to the World Health Organization (WHO), over a billion people--one-sixth of the world's population--lack access to safe water supplies.
Four billion cases of diarrheal disease occur worldwide every year, resulting in 1.8 million deaths, primarily infants and children in developing countries. Eighty-eight percent of this disease is attributed to unsafe water supplies, inadequate sanitation and hygiene.
In the United States, viruses are the target pathogenic microorganisms in the new Ground Water Rule under the Environmental Protection Agency's Safe Drinking Water Act, which took effect on Jan. 8.
“What is unique about our technology is its ability to remove viruses--the smallest of the pathogens--from water supplies,” Pei Chiu, an associate professor in UD's Department of Civil and Environmental Engineering, said.
Chiu collaborated with Yan Jin, a professor of environmental soil physics in UD's plant and soil sciences department, to develop the technology. They then sought the expertise of virologist Kali Kniel, an assistant professor in the animal and food sciences department, who has provided critical assistance with the testing phase.
“A serious challenge facing the water treatment industry is how to simultaneously control microbial pathogens, disinfectants such as chlorine, and toxic disinfection byproducts in our drinking water, and at an acceptable cost,” Chiu noted.
Viruses are difficult to eliminate in drinking water using current methods because they are far smaller than bacteria, highly mobile, and resistant to chlorination, which is the dominant disinfection method used in the United States, according to the researchers.
Of all the inhabitants of the microbial world, viruses are the smallest--as tiny as 10 nanometers. According to the American Society for Microbiology, if a virus could be enlarged to the size of a baseball, the average bacterium would be the size of the pitcher's mound, and a single cell in your body would be the size of a ballpark.
“By using elemental iron in the filtration process, we were able to remove viral agents from drinking water at very high efficiencies. Of a quarter of a million particles going in, only a few were going out,” Chiu noted.
The elemental or “zero-valent” iron (Fe) used in the technology is widely available as a byproduct of iron and steel production, and it is inexpensive, currently costing less than 40 cents a pound (~$750/ton). Viruses are either chemically inactivated by or irreversibly adsorbed to the iron, according to the scientists.
Technology removes 99.999 percent of viruses
The idea for the UD research sprang up when Jin and Chiu were discussing their respective projects over lunch one day.
Since joining UD in 1995, Jin's primary research area has been investigating the survival, attachment and transport behavior of viruses in soil and groundwater aquifers. One of the projects, which was sponsored by the American Water Works Association Research Foundation, involved testing virus transport potential in soils collected from different regions across the United States. Jin's group found that the soils high in iron and aluminum oxides removed viruses much more efficiently than those that didn't contain metal oxides.
“We knew that iron had been used to treat a variety of pollutants in groundwater, but no one had tested iron against biological agents,” Chiu said. So the two researchers decided to pursue some experiments.
With partial support from the U.S. Department of Agriculture and the Delaware Water Resources Center, through its graduate fellowship program, the scientists and their students began evaluating the effectiveness of iron granules in removing viruses from water under continuous flow conditions and over extended periods. Two bacteriophages--viruses that infect bacteria--were used in the initial lab studies.
Since then, Kniel has been documenting the technology's effectiveness against human pathogens including E. coli 0157:H7, hepatitis A, norovirus and rotavirus. Rotavirus is the number-one cause of diarrhea in children, according to Kniel.
“In 20 minutes, we found 99.99 percent removal of the viruses,” Chiu said. “And we found that removal of the viruses got even better than that with time, to more than 99.999 percent.”
The elemental iron also removed organic material, such as humic acid, that naturally occurs in groundwater and other sources of drinking water. During the disinfection process, this natural organic material can react with chlorine to produce a variety of toxic chemicals called disinfection byproducts.
“Our iron-based technology can help ensure drinking-water safety by reducing microbial pathogens and disinfection byproducts simultaneously,” Chiu noted.
Applications in agriculture and food safety
Besides helping to safeguard drinking water, the UD technology may have applications in agriculture.
Integrated into the wash-water system at a produce-packing house, it could help clean and safeguard fresh and “ready to eat” vegetables, particularly leafy greens like lettuce and spinach, as well as fruit, according to Kniel.
“Sometimes on farms, wash-water is recirculated, so this technology could help prevent plant pathogens from spreading to other plants,” she said.
This UD research underscores the importance of interdisciplinary study in solving problems.
“There are lots of exciting things you can discover working together,” Jin said, smiling. “In this project, we all need each other. Pei is the engineer and knows where we should put this step and how to scale it up. I study how viruses and other types of colloidal particles are transported in water, and Kali knows all about waterborne pathogens.
“Our hope is that the technology we've developed will help people in our country and around the world, especially in developing countries,” Jin noted.
Currently, the Centre for Affordable Water and Sanitation Technology in Calgary, Canada, is exploring use of the UD technology in a portable water treatment unit. Since 2001, the registered Canadian charity has provided technical training in water and sanitation to more than 300 organizations in 43 countries of the developing world, impacting nearly a million people.
Note: This story has been adapted from a news release issued by University of Delaware.
ool, Iron
Or if you have neither the time nor the inclination to boil water, iodine is equally effective. After 10 minutes (20 minutes for very cold water), a sufficient dose of iodine kills all protozoa, bacteria, and viruses. There are many iodination methods, and two excellent ones are commercially available.
I thought cutting cheese was a different malady.
FDA Reviewing Cold Drug Safety in Kids - Special Focus on Safety in Infants Less Than 2 Years Old
A Mix of Medicines That Can Be Lethal
FReepmail me if you want on or off my health and science ping list.
interesting, but I wish they'd go into a bit more detail about what they are doing and the mechanism of it.
There's a difference between "clean water in the 3rd world" and "totally sanitized water in the 1st world."
ping...in case you missed this... (Thanks, neverdem!)
L
Yup. Everywhere we look...another explanation of why we are who we are.
Thanks. I drink only distilled water.
One thing I learned from Six Sigma.
99.999% ain't so good.
Imagine if the airlines had that record? Would _ANYONE_ fly willingly?
This technology sounds great and all, but if these monkey's in the third world just boiled the water, the problem would go away.
That's what all the literature has said for years. In recent years though, there are some claims that iodine is less effective against a pathogen called cryptosporidium. Supposedly they are encysted and in practice hikers tend to find and treat very cold water, without sufficient time to for iodine to work its' magic.
I always wondered if this isn't portable water purifier manufacturer agitprop. I use a ceramic filter and a trace of iodine for raw water. As every schoolboy knows, household bleach can also be used for water purification (the unscented Chlorox type), a different form of chlorine is used for many municipal water supplies.
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You should filter first, then use the chemical treatments, at least that's my understanding. I don't have the figures handy, but far less iodine is required, not even enough to taste. The "two tablets per quart of water, allow a little leakage in the screw threads, wait 20 minutes" directions covered a lot of bases. Chlorine isn't so good because it becomes bound up/used up in organic matter like leaves, dirt and such. That's why a swimming pool gets so gnarly and red-eye producing - not because of the chlorine, but other "stuff".
Well, to each his own. The water up here in Alaska is pretty clean (no mud, gunk, etc) and I primary filter with cloth. I'd rather filter dead bugs than worry about them sitting the filter and getting me a second time.
Sone early versions of the First Need filter had a rep of holding onto the bad bug and geting you a second time.
And so, we do our best to avoid developing and utilizing our immune systems, just as viruses and bacteria become more and more drug-resistant.One thing I learned from Six Sigma.
"Dosage makes the poison." That means that:
- if you started out with mountain spring water having very few pathogens, purification is unnecessary and could even be counterproductive if it prevents the stimulation of the immune systems of the those who drink it.
- if you have slightly contaminated water, you will probably not get sick from drinking it but there is certainly no harm in treating it with this process.
- if you have moderately contaminated water, if untreated it will overwhelm your immune system and make you sick, possibly even fatally sick. The same water, if treated thru this system, would be perfectly safe to drink.
- water that is so polluted that removal/inactivation of all but 10 pathogens per million in the feedwater still leaves it nonpotable is pretty nasty stuff to begin with.
ping to my #39.
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