Louisville Water’s Research Benefits National Water Quality Efforts
Friday January 6, 2012
Research conducted in 2011 by Louisville Water scientists is drawing national attention as the company’s discoveries reduce hexavalent chromium (Cr6) to trace amounts, less than 0.1 part per billion.
While the Total Chromium levels in Louisville’s drinking water have always been 90% below the federal regulatory level, there are currently no standards for Cr6. Chromium is naturally occurring and exists in two forms: chromium 3 and chromium 6. Chromium 3 is important for balanced health. Studies have shown Cr6 can be carcinogenic if inhaled. The Environmental Protection Agency (EPA) is awaiting scientific-based studies to see at what level, if any, Cr6 poses a health concern if ingested.
Louisville Water’s research identified a practical approach in reducing Cr6 amounts in drinking water and now the company is helping lead a national research effort. Scientists discovered that a modification in the treatment process reduces Cr6 levels to below 0.1 ppb.
How the Research Began
Louisville Water began its research in January 2011 after the EPA recommended water utilities to monitor quarterly for Cr6 at the source, in the finished water and in the distribution system. Louisville Water decided to take the research a step further and examine each step of the treatment process at its two treatment plants. The scientists learned that ground water at its B.E. Payne Plant, which is naturally filtered in its riverbank filtration tunnel, has no Cr6. However, as the water moved through the treatment process, the Cr6 level increased to 0.28 ppb in the finished water, four times the level found in the finished water of the Crescent Hill Plant.
Scientists discovered a link between the chemical softening process in water treatment and Cr6. Louisville Water Company uses lime as the softening agent. Scientists learned that by moving the lime feed to the beginning of the treatment process the formation of Cr6 was significantly reduced. The absence of dissolved oxygen, the presence of ferrous ion and other reducing agents in the riverbank filtered water, such as iron sulfate, a mineral found in many nutritional supplements, also lowered the formation of Cr6.
Today, the finished drinking water for Louisville Water contains Cr6 levels that are less than 0.1 ppb.
"Louisville Water has aggressively responded to the Cr6 issue," said Phillip Brandhuber, PhD with HDR Engineering, a Colorado-based firm that will assist with a national Cr6 study. "Cr6 has only been detected at very low concentrations in their water. Yet they are performing internal research and funding external studies to develop new methods that may be able to reduce chromium 6 concentrations to levels below that obtained by current treatment technologies."
Louisville Water has shared its data with regional water utilities, the Kentucky Division of Water and the Water Research Foundation. The company is working with the Foundation, HDR Engineering and other utilities on a national study that will look to reduce Cr6 levels in drinking water. “What Louisville has done is really original,” said Rob Renner, Executive Director of the Water Research Foundation. “The utility went beyond what was required.” While each utility’s' treatment process is unique, the research in Louisville can help others understand how Cr6 is formed and how it can be managed in the treatment process.
"The work by our scientists is a testament of our commitment to innovation that advances the science of drinking water," said Greg Heitzman, President & CEO of Louisville Water. "I'm very proud of work our scientists have done and hope that our research can benefit water utilities across the United States."
Currently, the EPA is conducting research to determine if it will create a regulatory standard for Cr6. In the meantime, Louisville Water will continue its quarterly monitoring for Cr 6 and will continue to monitor for Total Chromium, which is regulated by the EPA. Current Total Chromium Levels in LWC drinking water are below 1ppb, 99% below the federal regulatory level of 100 ppb.