Water Treatment: Disinfecting Alternatives and Public Safety

In a report from the U.S. Chemical Safety and Hazard Investigation Board (CSB) a rail car released 48,000 pounds of chlorine into a neighboring community, resulting in hundreds of residents being evacuated or sheltered in place. Sixty-three local residents sought medical evacuation; three were admitted to the hospital. The chlorine caused tree leaves and vegetation around the facility to turn brown. This incident was caused by a ruptured transfer hose. (www.chemsafety.gov, Safety Bulleting, No. 2005-06-I-LA, June 2007).

The use of gas chlorine, and gas sulfur dioxide in the wastewater treatment industry, is slowly becoming a disinfecting method of the past. In today's water treatment world, the use of these two highly potential dangerous gases, raise several safety concerns. Along with these safety concerns for the public, treatment plants must meet strict requirements in order to use these chemicals. Now that stringent demands need to be met on these chemicals, many private and public owned water and wastewater facilities have noted that the risk of using these two gases, for disinfecting, are risky and not worth the potential of harming the public, the plant personnel and the environment.

Throughout wastewater history, gas chlorine has been used to kill pathogenic bacteria. For years this was the preferred method of disinfection. There are two reasons for this; first the chemicals low cost and second the strong effectiveness of the chemical. The same principle applies for sulfur dioxide a chemical in a gas form used to remove chlorine residual from the wastewater treatment plant final product or (plant effluent).