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Testing the Tap
Evaluating disinfection byproducts in drinking water
Environmental Engineer David Reckhow holds a drinking water sample in the lab

"The ultimate goal is to do as much as we can to protect the public from contaminants and reduce the risks of cancer as a result," says Reckhow.

For over a hundred years, chlorine and other drinking water disinfectants have saved lives that would otherwise be lost to cholera, hepatitis, typhoid fever, and dysentery. While chlorine has long been employed by water utilities as the most effective means of treating public drinking water and preventing such diseases, Environmental Engineering Professor David Reckhow and his team are conducting research that illustrates how its use leads to the formation of known carcinogenic compounds.

“Human exposure to disinfection byproducts (DBP’s) in tap water has been associated with elevated incidence of cancer and adverse reproductive outcomes. Reducing this exposure is a major challenge to the drinking water industry,” according to Reckhow Research Group, Department of Civil and Environmental Engineering.

Reckhow’s research goals are three-fold: to identify and quantify the presence of these carcinogens, to investigate methods to reduce their presence, and to search for alternative ways of purifying water. He calls much of his research “forensic chemistry.”

When water is treated with chlorine, a chemical reaction occurs. The chlorine atoms bind with naturally occurring organic compounds (from decomposing leaves and other plant material) forming chlorinated organic compounds. Despite their miniscule concentration (in the part per trillion range), these compounds are toxic enough to cause thousands of deaths each year nationwide and are strongly correlated with bladder cancer.

“There aren’t a lot of naturally occurring chlorinated organic compounds. Our bodies aren’t always that equipped to deal with them,” Reckhow says.

And surprisingly enough, new research in the Reckhow laboratory is revealing that people may be most vulnerable to chlorinated organic compounds in the shower.  In addition to water being absorbed through open skin pores, steam likely contains higher concentrations of the volatile chlorinated organic compounds. Once inhaled, the compounds can easily enter the bloodstream.

According to Reckhow, the reactions that leads to the formation of chlorinated organic compounds are accelerated by heat, and therefore by common household water heaters.  The longer the water ‘cooks,’ the greater the chances of exposure. For this reason, Reckhow speculates that on-demand water heaters may be better at reducing exposure as the water only heats during use, as opposed to water heaters that heat water continuously.

Similarly, the longer water travels through chlorinated pipelines, the more chlorinated organic compounds it is likely to contain. Reckhow explains that “not everybody gets the same water,” that the chemical properties of water change depending on its course.           

Because even more people would get sick without water disinfection, chlorine cannot be removed without a comparable alternative. Reckhow and his team have found viable alternatives that work, but not well enough to completely avoid the use of chlorine.  Considering how long water ‘sits around’ in pipes, the disinfectant cannot be allowed to dissipate or the water will be vulnerable to pathogens. “There’s not an ideal alternative to chlorine,” Reckhow says.

But every little bit helps. The Reckhow team recently completed a three-year project with New York City to help adjust chlorination levels so that they could meet the DBP standards without having to resort to other, more expensive methods.

“We essentially take what nature gives us. We can sometimes play with nature a little bit, but there’s only a limited number of options,” Reckhow says.

Using a high-tech device called a liquid chromatograph mass spectrometer the team is uniquely able to detect even those contaminants that are present at part per trillion levels. A sample is first placed in the liquid chromatograph where it is pumped through a long tube of special adsorbant resin. This separates the contaminants out and sends them (compound by compound) to the mass spectrometer. The spectrometer then ionizes the compounds with a three-step device called a triple quadrupole. Here the ionized compounds (parent ions) are separated by molecular weight, then broken up into characteristic molecular fragments (daughter ions), and finally separated once more in order to be quantified based on their weight. The computer can then identify each parent ion and determine the molecular weights of the various daughter ions, allowing the team to establish the identity of the contaminant and its concentration.

The Reckhow team is advising water utilities across New England and around the U.S., helping them to reassess the effectiveness of their water treatment facilities and consider utilizing new technologies. The team’s research and expertise has been applied in both New York City and Boston public water systems.

And with a new multi-year grant from the U.S. EPA, Reckhow and his team are testing an iron-based disinfectant, ferrate, which shows strong potential in its capacity to treat drinking water. The team will work with a dozen small drinking-water utilities around the state to conduct research in collaboration with Haskell University of Lawrence, Kansas.

Reckhow hopes to soon join forces with researchers in China who are already exploring ferrate capabilities. He is also working to set up projects in Uganda and South Africa.

In related research, Reckhow and his colleagues are making great strides in identifying and quantifying pharmaceuticals that enter water systems. Using gadolinium (a heavy metal) as an indicator of pharmaceutical-laden wastewater, the team is currently testing samples from the Assabet River of Eastern Massachusetts in one study.

Reckhow says that while the research process has been long, every step towards cleaner water is a step in the right direction.

“The ultimate goal is to do as much as we can to protect the public from contaminants and reduce the risks of cancer as a result,” says Reckhow.


Amanda Drane ‘12