Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Nature's helpers: Using microorganisms to remove TCE from water

03.03.2008
In 2002, Bruce Rittmann, PhD, director of the Biodesign Institute’s Center for Environmental Biotechnology, received a patent for an innovative way to use nature to lend society a hand. He invented a treatment system, called the membrane biofilm reactor (MBfR), which uses naturally occurring microorganisms to remove contaminants from water.

Now Rittmann and his research team, which includes Rosa Krajmalnik-Brown and Jinwook Chung, recently published a paper in the journal Environmental Science & Technology for a new application that removes a problematic contaminant that has made local headlines.

The chlorinated solvent trichloroethene (TCE) has been found to be an increasingly problematic contaminant in groundwater. The detection of TCE recently forced the shut down of the water supply for the Greater Phoenix area municipalities of Paradise Valley and Scottsdale.

TCE has been widely used as a cleaning agent and solvent for many military, commercial, and industrial applications. Its widespread use, along with its improper handling, storage, and disposal, has resulted in frequent detection of TCE in the groundwater. TCE has the potential to cause liver damage, malfunctions in the central nervous system and it is considered a likely human carcinogen.

“As with other elements, the chlorine cycle is becoming a key concern to many environmental pollution scientists,” said Krajmalnik-Brown, a researcher in the Biodesign Institute’s Center for Environmental Biotechnology and assistant professor in the Ira A. Fulton School of Engineering’s Department of Civil and Environmental Engineering.

Transforming the chlorinated solvent to a harmless product is the best way to eliminate the harmful effects of TCE. In the case of TCE, Mother Nature is the best helper. Scientists have discovered specialized microorganisms that can replace the chlorine in the chlorinated molecules with hydrogen, a process called reductive dechlorination. While other methods are possible, they are often more costly than reductive dechlorination on a large scale, and many do not transform TCE into a harmless end product.

In the paper, the Rittmann team utilized the MBfR and a naturally occurring group of microorganisms able to remove TCE from water. Surprisingly, these microorganisms, called dehalogenerators, have an affinity for chlorinated organics and can be found all throughout nature, even in clean water supplies, the soil, and groundwater.

“These bacteria respire TCE, that is, they can use TCE like we use oxygen to breathe,” said Krajmalnik-Brown. “They take in the TCE and they start removing the chlorines, step by step. In the ideal case, the dehalogenators remove all the chlorines, converting TCE to ethene, which is harmless.”

With this knowledge in hand, the challenge for the research team was to adapt their existing MfBR system, which can remove other water contaminants, to see if it could now handle TCE. A version of the reactor that addresses perchlorate, a byproduct of rocket fuel, is already in the commercialization pipeline.

“A key challenge with using these bacteria is that, if they don’t dechlorinate all the way, the TCE can be converted to vinyl chloride, which is a known human carcinogen,” said Krajmalnik-Brown. “In other words, if you don’t have complete dechlorination, you can end up having something worse than what you started with. So, it is critical to have the right mix of microorganisms for complete dechlorination.”

Their approach was simple in execution. They took an existing MBfR that was handling perchlorate removal and then introduced TCE into the system.

Rittmann’s MBfR works by delivering hydrogen gas to the bacteria through tiny hollow tubes submerged in water. In the right environment, the tubes become coated with a biofilm containing microorganisms. The system provides the microorganisms with hydrogen gas, which must be present for the microorganisms to change the chemical composition of a contaminant and render it harmless.

Their results indicated that the MBfR could be an incredibly versatile system, quickly adapting to now handle TCE. “This was really surprising, because there wasn’t any TCE at our pilot plant experiments prior to switching,” said Krajmalnik-Brown. “So there must have been really small amounts of the critical microorganisms in the culture. When shifted to TCE, they thrived and handled the contaminants.”

By assessing the MBfR community, they found the special dehalogenating bacteria that can take the hydrogen supplied by the MBfR and reduce TCE all the way to harmless ethene. Using the latest molecular techniques, they could not only identify the bacterial population to handle TCE, but also the genes within these populations that make enzymes that detoxify TCE to ethene.

The team found one particular organism, a new type of Dehalococcoides, the bacteria known to dechlorinate TCE all the way to ethene. They were also the first group to grow these dehalogenating bacteria in a biofilm in the lab.

“The bacteria are notoriously difficult to grow into a biofilm in the lab and study because they need hydrogen as an electron donor. An advantage of our system is that the MBfR can provide hydrogen through a membrane, which allows the microbial community to grow and naturally form a biofilm surrounding the membrane,” said Krajmalnik-Brown.

Next, the team hopes to drive the TCE system toward commercialization. Other oxidized contaminants that the system has been effective in reducing in the laboratory setting include perchlorate, selenate (found in coal wastes and agricultural drainage), chromate (found in industrial wastes), and other chlorinated solvents.

Joe Caspermeyer | EurekAlert!
Further information:
http://www.asu.edu

More articles from Ecology, The Environment and Conservation:

nachricht Value from wastewater
16.08.2017 | Hochschule Landshut

nachricht Species Richness – a false friend? Scientists want to improve biodiversity assessments
01.08.2017 | Carl von Ossietzky-Universität Oldenburg

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: Exotic quantum states made from light: Physicists create optical “wells” for a super-photon

Physicists at the University of Bonn have managed to create optical hollows and more complex patterns into which the light of a Bose-Einstein condensate flows. The creation of such highly low-loss structures for light is a prerequisite for complex light circuits, such as for quantum information processing for a new generation of computers. The researchers are now presenting their results in the journal Nature Photonics.

Light particles (photons) occur as tiny, indivisible portions. Many thousands of these light portions can be merged to form a single super-photon if they are...

Im Focus: Circular RNA linked to brain function

For the first time, scientists have shown that circular RNA is linked to brain function. When a RNA molecule called Cdr1as was deleted from the genome of mice, the animals had problems filtering out unnecessary information – like patients suffering from neuropsychiatric disorders.

While hundreds of circular RNAs (circRNAs) are abundant in mammalian brains, one big question has remained unanswered: What are they actually good for? In the...

Im Focus: RAVAN CubeSat measures Earth's outgoing energy

An experimental small satellite has successfully collected and delivered data on a key measurement for predicting changes in Earth's climate.

The Radiometer Assessment using Vertically Aligned Nanotubes (RAVAN) CubeSat was launched into low-Earth orbit on Nov. 11, 2016, in order to test new...

Im Focus: Scientists shine new light on the “other high temperature superconductor”

A study led by scientists of the Max Planck Institute for the Structure and Dynamics of Matter (MPSD) at the Center for Free-Electron Laser Science in Hamburg presents evidence of the coexistence of superconductivity and “charge-density-waves” in compounds of the poorly-studied family of bismuthates. This observation opens up new perspectives for a deeper understanding of the phenomenon of high-temperature superconductivity, a topic which is at the core of condensed matter research since more than 30 years. The paper by Nicoletti et al has been published in the PNAS.

Since the beginning of the 20th century, superconductivity had been observed in some metals at temperatures only a few degrees above the absolute zero (minus...

Im Focus: Scientists improve forecast of increasing hazard on Ecuadorian volcano

Researchers from the University of Miami (UM) Rosenstiel School of Marine and Atmospheric Science, the Italian Space Agency (ASI), and the Instituto Geofisico--Escuela Politecnica Nacional (IGEPN) of Ecuador, showed an increasing volcanic danger on Cotopaxi in Ecuador using a powerful technique known as Interferometric Synthetic Aperture Radar (InSAR).

The Andes region in which Cotopaxi volcano is located is known to contain some of the world's most serious volcanic hazard. A mid- to large-size eruption has...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Call for Papers – ICNFT 2018, 5th International Conference on New Forming Technology

16.08.2017 | Event News

Sustainability is the business model of tomorrow

04.08.2017 | Event News

Clash of Realities 2017: Registration now open. International Conference at TH Köln

26.07.2017 | Event News

 
Latest News

New thruster design increases efficiency for future spaceflight

16.08.2017 | Physics and Astronomy

Transporting spin: A graphene and boron nitride heterostructure creates large spin signals

16.08.2017 | Materials Sciences

A new method for the 3-D printing of living tissues

16.08.2017 | Interdisciplinary Research

VideoLinks
B2B-VideoLinks
More VideoLinks >>>