Featured Research

from universities, journals, and other organizations

Best ultraviolet-wavelength for keeping water free of microorganisms determined

Date:
April 21, 2010
Source:
American Friends of Tel Aviv University
Summary:
Scientists recently determined the optimal ultraviolet-light wavelength for keeping water free of microorganisms. They say that their brand new approach could be used by water treatment plants and desalination facilities to destroy these organisms and make these facilities more efficient.

Does your drinking water smell foul, or are you worried that chemicals might be damaging your family's health? Water treatment facilities currently use chlorine that produces carcinogenic by-products to keep your tapwater clean, but Tel Aviv University scientists have determined that ultra-violet (UV) light might be a better solution.

Related Articles


Dr. Hadas Mamane of Tel Aviv University's Porter School of Environmental Science and Faculty of Engineering, Prof. Eliora Ron of TAU's George S. Wise Faculty of Life Sciences and their doctoral student Anat Lakretz of TAU's School of Mechanical Engineering have recently determined the optimal UV wavelength for keeping water clean of microorganisms. Their approach could be used by water treatment plants as well as large-scale desalination facilities to destroy health-threatening microorganisms and make these facilities more efficient.

"UV light irradiation is being increasingly applied as a primary process for water disinfection," says Lakretz. "In our recent study, we've shown how this treatment can be optimized to kill free-swimming bacteria in the water -- the kinds that also stick inside water distribution pipes and clog filters in desalination plants by producing bacterial biofilms."

This undesired "stickiness" of bacteria to surfaces is called "bio-fouling," which costs taxpayers and governments billions of dollars each year. "No one should be drinking microorganisms in their water. In addition, when microorganisms get stuck in the pores of the membranes of filters, they create serious problems," says Lakretz.

Not all UV light is created equal

Irradiation could be used as a pre-treatment to inactivate suspended microorganisms in water, with the secondary goal of preventing bio-fouling. In their study, reported in the journal Biofouling, the researchers looked at targeted UV light wavelengths on the bacteria Pseudomonas aeruginosa, commonly found in drinking water.

The TAU researchers investigated UV wavelengths within between the 220-280 nanometre (nm) scale, and found that any wavelength between 254 and 270 nm effectively cleaned the water. Those in the same region were also best for keeping membranes clear of bacterial build-up in desalination plants, they reported. Special lamps that emit a multi-wavelength UV spectrum ― more advanced than the single-wavelength UV lamps found in home water systems ― were used.

The UV "zap" also prevented bacterial re-growth in the water after UV inactivation. "The best way to control and kill these micro-organisms was to damage their DNA," says Lakretz. "The damage that the UV light causes has no known negative effect on the water," she adds.

In addition, the prevention of biofilm formation by bacteria was UV dose-dependent. The researchers reported less bio-fouling when a bigger dose of UV light was applied to the water around the film.

A light to save lives

The approach is even more helpful against parasites that aren't adversely affected by chlorine treatment, such as Giarrdia and Cryptosporidium, two harmful parasites that cause severe diarrhea and can lead to death. Children, the elderly and those in developing nations are particularly vulnerable. "Sewage leakage into water supplies poses a big problem in terms of bacterial contamination, and is something UV light could remediate," says Lakretz.

Small amounts of chorine or other oxidants will still be necessary to make sure that residual bacteria don't enter the water further along the distribution pipeline. But Lakretz says this new approach to disinfecting water while controlling biofouling can also reduce the amount of carcinogenic by-products that chlorine produces.


Story Source:

The above story is based on materials provided by American Friends of Tel Aviv University. Note: Materials may be edited for content and length.


Cite This Page:

American Friends of Tel Aviv University. "Best ultraviolet-wavelength for keeping water free of microorganisms determined." ScienceDaily. ScienceDaily, 21 April 2010. <www.sciencedaily.com/releases/2010/04/100421162609.htm>.
American Friends of Tel Aviv University. (2010, April 21). Best ultraviolet-wavelength for keeping water free of microorganisms determined. ScienceDaily. Retrieved November 28, 2014 from www.sciencedaily.com/releases/2010/04/100421162609.htm
American Friends of Tel Aviv University. "Best ultraviolet-wavelength for keeping water free of microorganisms determined." ScienceDaily. www.sciencedaily.com/releases/2010/04/100421162609.htm (accessed November 28, 2014).

Share This


More From ScienceDaily



More Earth & Climate News

Friday, November 28, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Scientists Find Invisible Space Shield Protecting Earth

Scientists Find Invisible Space Shield Protecting Earth

Newsy (Nov. 27, 2014) — An invisible barrier is keeping dangerous super fast electrons from interfering with our atmosphere, but scientists aren't entirely sure how. Video provided by Newsy
Powered by NewsLook.com
Bolivian Recycling Initiative Turns Plastic Waste Into School Furniture

Bolivian Recycling Initiative Turns Plastic Waste Into School Furniture

Reuters - Innovations Video Online (Nov. 26, 2014) — Innovative recycling project in La Paz separates city waste and converts plastic garbage into school furniture made from 'plastiwood'. Tara Cleary reports. Video provided by Reuters
Powered by NewsLook.com
Blu-Ray Discs Getting Second Run As Solar Panels

Blu-Ray Discs Getting Second Run As Solar Panels

Newsy (Nov. 26, 2014) — Researchers at Northwestern University are repurposing Blu-ray movies for better solar panel technology thanks to the discs' internal structures. Video provided by Newsy
Powered by NewsLook.com
Antarctic Sea Ice Mystery Thickens... Literally

Antarctic Sea Ice Mystery Thickens... Literally

Newsy (Nov. 25, 2014) — Antarctic sea ice isn't only expanding, it's thicker than previously thought, and scientists aren't sure exactly why. Video provided by Newsy
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
 
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:  

Breaking News:

Strange & Offbeat Stories

 

Plants & Animals

Earth & Climate

Fossils & Ruins

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:  

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile iPhone Android Web
Follow Facebook Twitter Google+
Subscribe RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins