Treating Water With Ultraviolet Light
In October 2013, Greater Cincinnati Water Works (GCWW) began operating a $30 million state-of-the-art Ultraviolet (UV) Disinfection Treatment Facility – one of the most significant advancements in water treatment technology since Granular Activated Carbon (GAC) became the standard in the 90s.
GCWW is now the largest water utility in North America to use UV disinfection following sand filtration and Granular Activated Carbon (GAC) absorption. The addition of UV provides a multi-barrier treatment approach to protect public health.
UV disinfection has been identified by the US Environmental Protection Agency as one of the best technologies to inactivate microorganisms, such as Cryptosporidium (crypto) in drinking water. During the UV disinfection process, water flows through the UV unit. UV lamps, which are contained inside the UV unit, emit rays of intense light which shine through the water creating a disinfection process.
GCWW’s 19,600 square foot UV facility contains eight medium pressure UV units. Each unit contains five 20kW nominal-power lamps. GCWW’s UV facility can treat up to 240 million gallons of water per day.
The UV facility uses LED lighting, lighting timers and solar panels to reduce energy use and costs.
Why Do We Need UV Disinfection Treatment?
In 1993, more than 400,000 people became sick, many were hospitalized and several died following an outbreak of Cryptosporidium in Milwaukee, Wisconsin. To date, the Milwaukee outbreak is the largest epidemic of waterborne disease reported in U.S. history. This incident sparked years of research both in the water industry and at GCWW to find the most effective method to protect against microscopic organisms found in source water.
UV disinfection uses UV light, in low doses, to inactivate disease-causing microorganisms such as Cryptosporidium and Giardia. No chemicals are added, and there is no residual effect once the water leaves the UV unit. Chlorine, which is a commonly used disinfectant at water treatment plants, is ineffective in killing Cryptosporidium.
There are many serious concerns about the vulnerability of the Ohio River watershed to contamination, including microbial and viral contamination from emerging microorganisms that are resistant to chlorine disinfection, as well as future contamination issues that will need to be addressed.
New or unexpected contaminants are sure to be discovered in our source water in the future. UV disinfection, combined with GCWW's current treatment processes, provides an extra layer of protection against those contaminants. This is an important step in protecting public health now and in the future.
These issues remind us how precious our source waters are and how important it is to protect them from harmful substances. The best way to insure safe water at the tap is to keep our source waters clean.