PITTSBURGH 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
|Contact: Morgan Kelly|
University of Pittsburgh