May 14, 1999
Stephen Randtke and David Graham, professors of civil and environmental engineering, and Jerry deNoyelles, professor of systematics and ecology and co-director of the Kansas Biological Survey, got a $185,000 grant from the U.S. Geological Survey to study the chemical geosmin.
Geosmin is made by some species of bacteria and blue-green algae and adds a strong earthy and musty odor to water. An incredibly small amount of geosmin will make people turn up their noses.
According to Randtke, most people can sense five nanograms of geosmin per water liter -- the equivalent of one second in 6,400 years. The chemical is found in water supplies worldwide but is especially common in lakes and reservoirs. Sixty-four Kansas counties, most in the eastern half of the state, use lakes or reservoirs for their drinking water, according to the Kansas Department of Health and Environment.
No health effects have been associated with geosmin. The primary indicator of its presence in water is taste. Water with low geosmin levels has a slight musty taste treatable through the use of an adsorptive substance called powdered activated carbon (PAC), added to water at treatment plants. The water is then run through a filter, lowering the level of geosmin. PAC can control modest levels of geosmin, but high levels are a problem.
In 1995 the City of Lawrence had to close one of two water treatment plants for six weeks because of high geosmin levels. Water could not be treated to a point where the taste was not discernable.
"Closing down a treatment plant is not an option for towns that rely on a single source of drinking water," Randtke said. "There are presently no inexpensive treatment options besides PAC adsorption."
Consumer confidence in water and in water utility companies is shaken when water takes on the odor and taste of geosmin. Several water utility companies are participating in the study, including the City of Lawrence Utilities Department, Shawnee Rural Water District No. 8, the City of Wichita and the Rathbun (Iowa) Regional Water Association.
Randtke, Graham, deNoyelles and Shugen Pan, graduate research assistant, are studying the origins of geosmin, specifically what causes high levels or "severe episodes," by adding varying levels and brands of PAC to water samples. The team is also exploring ways to improve methods of using PAC and affordable treatment alternatives. The study will run until September 2000.