Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Riverbank filtration pulls pollutants from drinking water

26.08.2004


Soil beside the stream can remove harmful microbes and organic material, researchers find



Harmful contaminants often taint drinking water drawn directly from a river, but a low-cost natural filter may lie just beyond the banks. Johns Hopkins researchers have found that the soil alongside a river can remove dangerous microbes and organic material as water flows through it. The cleaner water is then pumped to the surface through wells drilled a short distance from the river.

This technique, called riverbank filtration, has been used in Europe for more than 50 years to improve the taste and smell of drinking water and to remove some hazardous pollutants such as industrial solvents. But after studying these natural filtration processes for six years at three rivers in the Midwestern United States, Johns Hopkins researchers have determined that passing river water through nearby sediment can produce other health benefits and may cut water treatment costs.


Josh Weiss, a doctoral student in the university’s Department of Geography and Environmental Engineering, presented the most recent research results on Aug. 25 in Philadelphia at the 228th national meeting of the American Chemical Society. He reported that riverbank filtration appears to significantly decrease the presence of bacteria and viruses. Water analyses also showed encouraging, though not definitive, signs that this technique can curtail Giardia and Cryptosporidium, two waterborne microorganisms that cause serious digestive ailments.

The latest results confirm the value of riverbank filtration, Weiss said. "It sounds counter-intuitive to drill wells nearby when water can be taken directly from a river," he said. "But our research indicates that riverbank filtration can naturally remove pathogens and organic material that can cause health problems, including some microbes that are able to survive conventional disinfection systems. If you think about how much it costs to build a full-scale treatment plant to make river water safe to drink, you can see how this could be very beneficial."

The research has been supported by Environmental Protection Agency grants awarded to a team led by Weiss’ doctoral advisor, Edward J. Bouwer, a professor in the Department of Geography and Environmental Engineering. The team has been studying water drawn from commercial wells located beside the Wabash, Ohio and Missouri rivers near Terre Haute, Ind.; Louisville, Ky.; and Kansas City, Mo.

In several recent papers published in peer-reviewed journals, Weiss, Bouwer and their colleagues have reported that riverbank filtration helps remove organic material left behind by decaying plants. In its natural state, this material poses no health hazards, but exposure to common water treatment chemicals such as chlorine can transform the material into cancer-causing compounds called disinfection byproducts.

"For this reason, it’s a good idea to remove as much of this organic matter as we can from the water before it’s treated with chemicals," Bouwer said. "Our research indicates that with riverbank filtration, we wind up with fewer of these dangerous disinfection byproducts in the drinking water."

Bouwer added, "Riverbank filtration doesn’t completely eliminate the need for water treatment. But it should lower the treatment costs and reduce the risks of mixing chlorine with the organic material that can become carcinogenic."

The researchers studied wells that had been constructed at varying distances – from 90 to 580 feet – from the three rivers. Over a period of days or weeks, river water moves outward toward these wells. As it travels through the sediment, the water is exposed to physical, chemical and biological processes that help remove impurities, the researchers say. Large particles may be pulled out by a straining process. Some of the chemical contaminants and microbes react with components in the sediment and remain behind, too. As a result, the water that reaches the wells is significantly cleaner than it was when it left the river.

In a campus lab, the Johns Hopkins researchers are trying to learn more about this natural filtration process by sending samples of river water through glass columns filled with sediment. They believe that soil characteristics and environmental factors such as the amount of river flow may also affect the natural filtration process.

Weiss, who is preparing his doctoral thesis on riverbank filtration, says the technique may not be appropriate in some areas, such as regions of the Western United States where rivers typically dry up in the summer. But in communities that depend on rivers for a year-round supply of drinking water, Weiss expects riverbank filtration to become more common in the coming years. "We definitely think riverbank filtration is worthwhile," he said. "We’re letting nature maintain the system, minimizing the need for external maintenance and the associated costs."

Phil Sneiderman | EurekAlert!
Further information:
http://www.jhu.edu

More articles from Ecology, The Environment and Conservation:

nachricht Bioinvasion on the rise
15.02.2017 | Universität Konstanz

nachricht Litter Levels in the Depths of the Arctic are On the Rise
10.02.2017 | Alfred-Wegener-Institut, Helmholtz-Zentrum für Polar- und Meeresforschung

All articles from Ecology, The Environment and Conservation >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Breakthrough with a chain of gold atoms

In the field of nanoscience, an international team of physicists with participants from Konstanz has achieved a breakthrough in understanding heat transport

In the field of nanoscience, an international team of physicists with participants from Konstanz has achieved a breakthrough in understanding heat transport

Im Focus: DNA repair: a new letter in the cell alphabet

Results reveal how discoveries may be hidden in scientific “blind spots”

Cells need to repair damaged DNA in our genes to prevent the development of cancer and other diseases. Our cells therefore activate and send “repair-proteins”...

Im Focus: Dresdner scientists print tomorrow’s world

The Fraunhofer IWS Dresden and Technische Universität Dresden inaugurated their jointly operated Center for Additive Manufacturing Dresden (AMCD) with a festive ceremony on February 7, 2017. Scientists from various disciplines perform research on materials, additive manufacturing processes and innovative technologies, which build up components in a layer by layer process. This technology opens up new horizons for component design and combinations of functions. For example during fabrication, electrical conductors and sensors are already able to be additively manufactured into components. They provide information about stress conditions of a product during operation.

The 3D-printing technology, or additive manufacturing as it is often called, has long made the step out of scientific research laboratories into industrial...

Im Focus: Mimicking nature's cellular architectures via 3-D printing

Research offers new level of control over the structure of 3-D printed materials

Nature does amazing things with limited design materials. Grass, for example, can support its own weight, resist strong wind loads, and recover after being...

Im Focus: Three Magnetic States for Each Hole

Nanometer-scale magnetic perforated grids could create new possibilities for computing. Together with international colleagues, scientists from the Helmholtz Zentrum Dresden-Rossendorf (HZDR) have shown how a cobalt grid can be reliably programmed at room temperature. In addition they discovered that for every hole ("antidot") three magnetic states can be configured. The results have been published in the journal "Scientific Reports".

Physicist Dr. Rantej Bali from the HZDR, together with scientists from Singapore and Australia, designed a special grid structure in a thin layer of cobalt in...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Booth and panel discussion – The Lindau Nobel Laureate Meetings at the AAAS 2017 Annual Meeting

13.02.2017 | Event News

Complex Loading versus Hidden Reserves

10.02.2017 | Event News

International Conference on Crystal Growth in Freiburg

09.02.2017 | Event News

 
Latest News

Switched-on DNA

20.02.2017 | Materials Sciences

Second cause of hidden hearing loss identified

20.02.2017 | Health and Medicine

Prospect for more effective treatment of nerve pain

20.02.2017 | Health and Medicine

VideoLinks
B2B-VideoLinks
More VideoLinks >>>