"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 carcinogenic and their levels in drinking water are regulated by the U.S. Environmental Protection Agency.
But Kroll and his colleagues have confirmed in their study that the stability of the monochloramine may have its drawbacks as well. Treatment with free chlorine, because it is more reactive, can lead to rapid degradation of chemical threats as well as early detection of contamination. As it reacts with a contaminant, chlorine levels in the water drop. Many municipalities use chlorine levels as indicators of possible contamination.
Monochloramine also requires more time to kill microbial contaminants in water. This should not be an issue in treatment plants, as water in monochloramine facilities can be held longer. "In the event of contamination of the water supply after it leaves the treatment plant, though, monochloramine has the potential as being not as effective as chlorine, since there is little control over the contact time," says Kroll.
Kroll is not recommending that system that have already switched to monochloramine switch back. Instead, he wants water quality professionals to recognize that if they have a monochloramine system, they can no longer rely solely on a sudden drop in disinfectant levels to alert them to a potential contaminant. He also recommends that, where possible, some level of free chlorine should be kept in the system.
And if a municipality has a free chlorine-based system, provides water to a high-profile target such as a military base, and are considering the switch to monochloramine, they may want to consider other methods of controlling disinfection byproducts to help comply with EPA regulations.
"The findings in these studies have significant repercussions as to the safety and security of our nations water supplies," says Kroll.
Jim Sliwa | EurekAlert!
Complete skin regeneration system of fish unraveled
24.04.2018 | Tokyo Institute of Technology
Scientists generate an atlas of the human genome using stem cells
24.04.2018 | The Hebrew University of Jerusalem
At the Hannover Messe 2018, the Bundesanstalt für Materialforschung und-prüfung (BAM) will show how, in the future, astronauts could produce their own tools or spare parts in zero gravity using 3D printing. This will reduce, weight and transport costs for space missions. Visitors can experience the innovative additive manufacturing process live at the fair.
Powder-based additive manufacturing in zero gravity is the name of the project in which a component is produced by applying metallic powder layers and then...
Physicists at the Laboratory for Attosecond Physics, which is jointly run by Ludwig-Maximilians-Universität and the Max Planck Institute of Quantum Optics, have developed a high-power laser system that generates ultrashort pulses of light covering a large share of the mid-infrared spectrum. The researchers envisage a wide range of applications for the technology – in the early diagnosis of cancer, for instance.
Molecules are the building blocks of life. Like all other organisms, we are made of them. They control our biorhythm, and they can also reflect our state of...
University of Connecticut researchers have created a biodegradable composite made of silk fibers that can be used to repair broken load-bearing bones without the complications sometimes presented by other materials.
Repairing major load-bearing bones such as those in the leg can be a long and uncomfortable process.
Study published in the journal ACS Applied Materials & Interfaces is the outcome of an international effort that included teams from Dresden and Berlin in Germany, and the US.
Scientists at the Helmholtz-Zentrum Dresden-Rossendorf (HZDR) together with colleagues from the Helmholtz-Zentrum Berlin (HZB) and the University of Virginia...
Novel highly efficient and brilliant gamma-ray source: Based on model calculations, physicists of the Max PIanck Institute for Nuclear Physics in Heidelberg propose a novel method for an efficient high-brilliance gamma-ray source. A giant collimated gamma-ray pulse is generated from the interaction of a dense ultra-relativistic electron beam with a thin solid conductor. Energetic gamma-rays are copiously produced as the electron beam splits into filaments while propagating across the conductor. The resulting gamma-ray energy and flux enable novel experiments in nuclear and fundamental physics.
The typical wavelength of light interacting with an object of the microcosm scales with the size of this object. For atoms, this ranges from visible light to...
13.04.2018 | Event News
12.04.2018 | Event News
09.04.2018 | Event News
24.04.2018 | Life Sciences
24.04.2018 | Materials Sciences
24.04.2018 | Trade Fair News