A Century of Chlorination

Perspective on a Century of Chlorination
Jan 04, 2009

Article originally from American Chemistry magazine.

For an industry expert’s perspective on the 100th anniversary of the chlorinationof U.S. drinking water, the American Chemistry Council (ACC) interviewed Dr. James P. Brennan, Technology Manager with Arch Chemicals in Smyrna, Ga., who has worked extensively with water chlorination chemistry for more than 30 years.

“The chlorination process has long been the conventional method of disinfection for municipal water and wastewater, due to its low chemical cost and consistent performance,” he says.

Beyond drinking water, chlorine disinfection is an important component to healthyswimming pools, schools, daycare centers, and restaurants. As Brennan puts it, chlorine and the chlorination process are used for everything from preventing the transmission of disease to reducing spoilage in freshly harvested fruits and vegetables.

“Chlorine had a marvelous effect on public health during the first 50 years of use,” hesays. “Through the chlorination process, the average lifespan went from 49 to 70 years.”

During that time, he adds, the basic principle of cleaning and sanitizing had already begun; and because of the concepts of good hygiene, the population as a whole benefited.

Chlorine can be applied to water as a gas (elemental chlorine), a liquid solution (sodiumhypochlorite), or in several dry forms. A granular form of dry chlorine (calcium hypochlorite), introduced 80 years ago, was stronger and had a longer shelf life. This product also evolved and is now easier to handle and store than ever.

“One success begets another, and chlorine evolved in its uses and its forms,” says Brennan.
More recently, he says, this product has become available in consistent tablet forms with delivery systems designed to provide dosage control and convenience, resulting in higher-quality treated water.

Calcium hypochlorite is also used in municipal water treatment plants and for sanitizing pools and spas. Private owners of pools and spas can conveniently transport and store it, and plant operators can easily apply it directly to the source, which is imperative for stopping the transmission of diseases.

Over the past 30 years, Brennan’s career has taken him from the laboratory bench to field locations throughout the U.S. and, more recently, around the globe. Most interesting and rewarding to him has been the opportunity to educate others about the chlorination process, particularly in underdeveloped areas in Asia and South America, where he has traveled in efforts to improve public health by emphasizing the importance of safe drinking water and how to treat it efficiently and reliably.

"We are teaching sustainable methods to treat water,” he says. “We want to keep the process simple and teach people how to use the products and protect their water sources.”

Looking ahead, Brennan says he believes improvements to the chlorination process are always evolving, especially in ways to make it more available and reliable.

And for the enormous effect chlorine has had on everything from public health to ensuring safe drinking water, he says, “Job well done.”