WASHINGTON, DC March 1, 2007 -- The results of what may be the most extensive comparison of two common disinfectants used by municipal water systems suggest that, from a security standpoint, traditional chlorination may be more effective than treatment with monochloramine.
"We have found something that is not necessarily a surprise but has important implications. These are considerations that water quality professionals should take into account if they have switched or are considering switching to a monochloramine disinfection system," says Dan Kroll, Chief Scientist at Hach Homeland Security in Loveland, Colorado, and lead researcher on the study, presented today at the ASM Biodefense and Emerging Disease Research Meeting.
As part of a recent endeavor to develop a system for online, continuous monitoring of drinking water distribution networks, Kroll and his colleagues, in coordination with the Army Corps of Engineers, studied the interactions of a wide variety of potential waterborne threat agents (both biological and chemical) with different levels of either free chlorine or monochloramine present. They tested dozens of potential hazards, from pesticides to disease-causing bacteria to chemical warfare agents.
The researchers discovered that not only is monochloramine less reactive than free chlorine against a number of chemical threats, it also is a slightly less efficient disinfectant, requiring a longer time to kill bacterial contaminants.
Scientists have long known that monochloramine is a more stable compound, and that is part of the reason it is becoming more popular as an alternative to chlorine in municipal water systems. Free chlorine has traditionally been the disinfectant of choice for municipal water systems throughout the 20th century, but it has some drawbacks. It can react with organic materials in drinking water to produce chlorine by-products. Some of these by-products are considered carcinogeni
Contact: Jim Sliwa
American Society for Microbiology