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INNOVATIVE RESEARCH FOR A SUSTAINABLE FUTURE
Evaluation of Current Water Treatment and Distribution System Optimization
to Provide Safe Drinking Water from Various Source Water Types and Conditions
Risk Management Research Project - Addressing Drinking Water Challenges through Science and Innovation
Background & Problem
Increasingly, drinking water treatment plants (DWTPs) are being challenged by
changes in the quality of their source waters and by their aging treatment and
distribution system infrastructure. Individually or in combination, factors such as
shrinking water and financial resources, climate change, agricultural runoff, harmful
algal blooms (HABs), and industrial land utilization increase the probability that
contaminants of emerging concern (CECs), such as pesticides, Pharmaceuticals,
personal care products, endocrine disrupting compounds, and algal toxins will remain
after treatment, ending up in consumers' drinking water. In addition, when treating for CECs, disinfection byproducts
(DBPs) can form, which may pose health risks as well. This is likely to disproportionately affect small drinking water
systems due to, among other factors, limited resources and treatment options.
Purpose of the Studies
Identifying and quantifying the source water and treatment challenges for water systems is an important step towards
mitigating present and future risks. An evaluation of potential of water contaminants in the natural environment and
during drinking water treatment is needed, particularly as we continue to adapt existing drinking water treatment
infrastructure to address CECs. The following studies will help improve our understanding of the propagation of
contaminants through drinking water treatment, and identify the best approaches for removal.
Results and Observations to Date
The source and finished waters from 26 DWTPs with various treatment configurations were analyzed for the
occurrence and treatment viability of estrogens and other CECs, as well as other water quality measures. The results
showed concentrations of androgens, estrogens, antibacterial compounds, and atrazine at the source and the finished
water at a single time point.
*J* Of the pesticides, atrazine was highly resistant to removal via conventional water treatment. Advanced treatment,
including ozonation and granular activated carbon filtration, appears to be most effective at reducing atrazine
concentrations. Trenbolone appears to show a similar trend, but the further study is needed to validate this.
*J* Of the estrogenic steroid hormones, only estrone (El) was observed in 10 DWTP source waters with a maximum
observed concentration of 0.38 ng/mL and a median of 0.10 ng/mL; however, all of the DWTPs were effective at
removing El so it was detected in the finished waters.
*J* Of the antibacterial agents analyzed in the DWTPs source waters, triclosan was detected in 8 and triclocarban (TCC)
was detected in 7. They were significantly reduced or removed during treatment at all of the DWTPs. Over 95%
removal was observed for triclosan and 90% for TCC at the source and the final product water at a single time point.
*J* All other androgenic compounds and remaining estrogens, were only detected in the source waters of two DWTPs.
Related Publications:
Schenck K., et al. (2012). Removal of estrogens and estrogenicity through drinking water treatment. Journal of Water and
Health, 10(1), 43-55.
Mash H. (2010). Assessing the fate and transformation by-product potential of trenbolone during chlorination.
Chemosphere, 81(7), 946-953.
Mash H., et al. (2010). Hypochlorite oxidation of select androgenic steroids. Water Research, 44(6), 1950-1960.
U.S. Environmental Protection Agency, Office of Research and Development
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The propagation of cyanobacteria and associated
toxins (nodularin and 8 microcystins) from the water source
through the treatment processes of full-scale DWTPs along
Lake Erie is being monitored. The study, which began during
the 2013 bloom season (Figure 1), takes place between April
and November of each bloom season, and is anticipated to
continue through the 2015. The concentrations of toxins are
being evaluated using Enzyme-Linked Immunosorbent Assay
(ELISA) and Liquid Chromatography-Mass Spectroscopy (LC-
MS) methods at each stage of the drinking water treatment
process, both for the extracellular matrix and the total
matrix following cell lysis. In addition, the concentrations of
intact cells in suspension are being quantified with
chlorophyll analysis. This monitoring regimen should improve
our understanding of the dynamics of algal toxin release and
removal through drinking water treatment processes. It is anticipated that the results of this study will be submitted for
publication in 2015. Some of the preliminary observations are listed below:
*«» The influent water quality, as measured by nitrate, cyanobacteria toxin, and cyanobacteria cell concentrations, is
significantly degraded in the western versus the central basin of Lake Erie.
*J* The bulk of cyanobacterial toxin present in the source water influents is contained within intact cyanobacterial
cells. After exposure to permanganate oxidation, a number of cells die and release toxins, which increases the
extracellular toxin load as measured by ELISA and LC-MS. The level then drops after additional treatment steps.
*J* The influent toxin load may be controlled by removing intact cells in the clarification and filtration processes. This
observation implies that a facility originally designed for particulate control can, with careful operation, serve as an
effective barrier against human exposure to cyanobacterial toxins.
The kinetics of oxidation/transformation of biotoxins associated with microcystins, aflatoxins (fungal toxins),
and other algal toxins is being evaluated through the treatment processes of full-scale DWTPs along Lake Erie. As the
propagation of biotoxins through drinking water treatment was analyzed, one of the primary observations was that the
release of toxins from cells following lysis can result in toxin levels in the extracellular matrix, even if earlier treatment
steps might have quickly removed toxin from bulk solution. To address this issue, the kinetics of degradation and
formation of associated DBPs are being investigated. The current study involves the chlorination of a number of algal
toxins and aflatoxins to determine their rates of degradation, coupled with an investigation of the DBPs generated. A
number of DBPs were observed, including oxidation and chlorinated substitution DBPs, both of which varied in speciation
dependent on chlorine contact time. It is anticipated that the results of this study will be submitted for publication in
2015. Some of the preliminary kinetic results indicate the following:
*J* Because of reactions centered at the tryptophan moiety, the rate of reaction for
the microcystin variants MYC-WR and MYC-LW were approximately 2-3 orders of
magnitude faster than the other MYCs studied, which were on the order of hours.
*J* Chlorine contact time during treatment is an important consideration for toxin
removal, although the toxicity of chlorinated DBPs hasn't been established.
Principal Investigators
Expected Outcomes
The approaches in these studies will develop an improved understanding of the optimal
conditions for existing drinking water infrastructure to reduce propagation of HAB-
associated toxins and other CECs through drinking water treatment plants. In addition,
the evaluations will provide a comparative utility of ELISA and LC/MS assays for
cyanobacterial toxin monitoring, and identify parameters most likely to impact the
accuracy of the different methods. Such information is critical to the design of effective
treatment practices and ultimately helps to prevent waterborne illnesses and safeguard
human health.
Heath Mash
(513)569-7713
mash.heath@epa.gov
Nicholas Dugan
(513)569-7239
dugan.nicholas@epa.gov
Darren Lytle
(513)569-7432
lytle.darren@epa.gov
Susan Glassmeyer
(513)569-7526
glassmeyer.susan@epa.gov
U.S. Environmental Protection Agency, Office of Research and Development
EPA/600/F-14/353 | September 2014
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