Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Pitt study finds 'green' water treatments may not kill bacteria in large building cooling systems

13.12.2010
Pitt Study Suggests Nonchemical Water Treatments Touted As “Green” Fail to Prevent Bacterial Growth in Air-Cooling Systems Found in Hospitals, Large Buildings

Five devices pitched as alternatives to chemical water treatment for water-based air-conditioning systems allowed the same rate of bacterial growth as untreated water, Pitt researchers found in two-year study.

Nonchemical treatment systems are touted as environmentally conscious stand-ins for such chemicals as chlorine when it comes to cleaning the water-based air-conditioning systems found in many large buildings. But a recent study by University of Pittsburgh researchers suggests that this diverse class of water-treatment devices may be ineffective and can allow dangerous bacteria to flourish in the cooling systems of hospitals, commercial offices, and other water-cooled buildings almost as much as they do in untreated water.

The two-year study by a team in Pitt’s Swanson School of Engineering is the first to thoroughly investigate the ability of nonchemical treatment devices (NCDs) to control the growth of bacteria in water-based cooling systems. Of the five NCDs tested, none significantly prevented bacterial growth. On the other hand, the researchers found that standard chlorine treatment controlled these organisms, even after bacteria had been allowed to proliferate.

“Our results suggest that equipment operators, building owners, and engineers should monitor systems that rely on NCDs to control microorganisms,” said coinvestigator Janet Stout, a research associate in the Swanson School’s Department of Civil and Environmental Engineering and director of the Pittsburgh-based Special Pathogens Laboratory. Stout worked with fellow lead investigator Radisav Vidic, chair and William Kepler Whiteford Professor of civil and environmental engineering, and Pitt civil engineering graduate student Scott Duda.

“These cooling systems are energy efficient and, if properly treated, very safe,” Stout continued. “But based on our results, nonchemical devices alone may not be enough to control microbial growth. One possible measure is to add chemical treatment as needed to prevent a potential health hazard.”

The air systems the team investigated work by piping chilled water throughout a building. The water warms as it exchanges temperature with the surrounding air and becomes a hotbed of microorganisms before returning to a central cooling tower to be cleaned and re-chilled.

If the returning water is not thoroughly cleaned, bacteria can spread throughout the system, exposing people within the building to possible infection and hampering the system’s energy efficiency.

The team constructed two scale models of typical cooling towers. One model remained untreated while the other was treated with five commercially available NCDs installed according to the manufacturers’ guidelines. Each device was tested for four weeks. Chlorine was administered three times during the study to demonstrate that an industry-accepted chemical treatment could kill bacteria even in a heavily contaminated system.

The five devices tested represent different classes of NCDs, Vidic said. Pulsed electric-field devices emit electromagnetic energy that, in theory, ruptures bacterial membranes and activates particles that ensnare the bacterium. Electrostatic devices function similarly by producing a constant static field.

Ultrasonic devices pass a mixture of untreated water and high-pressure air through a chamber that purportedly disintegrates the bacterium with sound waves.

For hydrodynamic cavitation devices, two cone-shaped water streams collide to form a vacuum region filled with high-friction bubbles that collide with and presumably deactivate the bacteria. Finally, the team tested a magnetic device, although magnetic NCDs are intended to prevent mineral buildup, not control bacterial growth.

The study was funded by the American Society of Heating, Refrigerating, and Air-Conditioning Engineers.

University Units
Swanson School of Engineering

Morgan Kelly | EurekAlert!
Further information:
http://www.pitt.edu

More articles from Studies and Analyses:

nachricht Real-time feedback helps save energy and water
08.02.2017 | Otto-Friedrich-Universität Bamberg

nachricht The Great Unknown: Risk-Taking Behavior in Adolescents
19.01.2017 | Max-Planck-Institut für Bildungsforschung

All articles from Studies and Analyses >>>

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

Biocompatible 3-D tracking system has potential to improve robot-assisted surgery

17.02.2017 | Medical Engineering

Real-time MRI analysis powered by supercomputers

17.02.2017 | Medical Engineering

Antibiotic effective against drug-resistant bacteria in pediatric skin infections

17.02.2017 | Health and Medicine

VideoLinks
B2B-VideoLinks
More VideoLinks >>>