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Fate of Artificial Sweeteners in Wastewater Treatment Plants in New York State, USA Bikram Subedi, and Kurunthachalam Kannan Environ. Sci. Technol., Just Accepted Manuscript • DOI: 10.1021/es504769c • Publication Date (Web): 03 Nov 2014 Downloaded from http://pubs.acs.org on November 13, 2014
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Environmental Science & Technology
Fate of Artificial Sweeteners in Wastewater Treatment Plants in New York State, USA
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Bikram Subedia and Kurunthachalam Kannana,b,*
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a
Wadsworth Center, New York State Department of Health, and Department of Environmental Health Sciences, School of Public Health, State University of New York at Albany, Empire State Plaza, P.O. Box 509, Albany, New York 12201-0509, United States
b
Biochemistry Department, Faculty of Science and Experimental Biochemistry Unit, King Fahd Medical Research Center, King Abdulaziz University, Jeddah 21589, Saudi Arabia
*Corresponding author: K. Kannan Wadsworth Center Empire State Plaza, P.O. Box 509 Albany, NY 12201-0509 Tel: 1-518-474-0015 Fax: 1-518-473-2895 E-mail:
[email protected] For submission to: Environmental Science and Technology
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ABSTRACT Very few studies describe the fate of artificial sweeteners (ASWs) in wastewater
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treatment plants (WWTPs). In this study, mass loadings, removal efficiencies, and environmental
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emission of sucralose, saccharin, aspartame, and acesulfame were determined based on the
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concentrations measured in wastewater influent, primary effluent, effluent, suspended particulate
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matter (SPM), and sludge collected from two WWTPs in the Albany area of New York State,
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USA. All ASWs were detected at a mean concentration that ranged from 0.13 (aspartame) to
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29.4 µg/L (sucralose) in wastewater influent, 0.49 (aspartame) to 27.7 µg/L (sucralose) in
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primary influent, 0.11 (aspartame) to 29.6 µg/L (sucralose) in effluent, and from 0.08
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(aspartame) to 0.65 µg/g dw (sucralose) in sludge. This is the first report of occurrence of ASWs
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in SPM; aspartame was found in 92% of influent SPM samples at a mean concentration of 444
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ng/g dw, followed by acesulfame (92 ng/g) and saccharin (49 ng/g). The fraction of the total
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mass of ASWs sorbed to SPM was in the rank order of: aspartame (50.4%) > acesulfame
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(10.9%) > saccharin and sucralose (0.8%). The sorption coefficients (Kd) of ASWs ranged from
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4.10 (saccharin) to 4540 L/kg (aspartame). Significant removal of aspartame (68.2%) and
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saccharin (90.3%) was found in WWTPs; however, sucralose and acesulfame were less
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efficiently removed ($170 million in 2004.4,5 The global consumption of acesulfame
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and saccharin in 2005 was 4 and 37 thousand metric tons, respectively.6
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ASWs are excreted mostly unchanged from the human body, flow down the drain, and
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are discharged into the environment through wastewater treatment plants (WWTPs).7,8
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Hydrophilic ASWs (solubility = 565-9.1 x 105 mg/L at 25° C) (Table 1) are not efficiently
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removed through wastewater treatment processes. For instance, removal efficiencies for
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acesulfame and sucralose in WWTPs were reported to be saccharin > acesulfame > sucralose, whereas that in the USA was: sucralose >
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aspartame ~ saccharin > acesulfame. The concentration of sucralose in sludge from the USA was
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an order of magnitude higher than that found in Korea; however, the concentrations of aspartame
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and saccharin in Korea were 2–3 times higher than those found in the USA. The differences in
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the patterns of ASWs in sludge in the USA and Korea suggest differences in per-capita
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consumption of individual ASWs and the removal in WWTP treatment processes. Sucralose is
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the most frequently used ASW in the USA and is found in ~1500 products as compared to
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acesulfame (1103 products) and aspartame (974 products);30 however, aspartame is the most
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widely used ASW in processed foods at relatively higher concentrations (as much as 5602
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mg/kg) in Korea.31,32
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Artificial Sweeteners in Suspended Particulate Matter. This is the first report of
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occurrence of ASWs in SPM; aspartame was found in 92% of influent SPM samples at a mean
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concentration of 444 ng/g dw, followed by acesulfame (92 ng/g) and saccharin (49 ng/g). The
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fraction of ASWs partitioned to SPM was calculated based on the measured concentrations in
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aqueous (i.e., dissolved) fraction and SPM (equation 1). The fraction of the total mass of ASWs
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Environmental Science & Technology
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sorbed to SPM (PSPM), on average, was in the rank order of aspartame (50.4%) > acesulfame
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(10.9%) > saccharin and sucralose (0.8%). Aspartame was found to sorb to SPM by as much as
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91% of the total mass; therefore, estimation of mass loadings of aspartame based only on
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dissolved fraction of wastewater can underestimate the total load by as much as 91%. In
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comparison, >90% of the loadings of acesulfame, saccharin, and sucralose in WWTPs were
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found in dissolved fraction.
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The sorption coefficients (Kd) of ASWs calculated based on the concentrations measured
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in influent (ng/L) and SPM (ng/kg dw) ranged from 4.10 (saccharin) to 4540 L/kg (aspartame)
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(Table 3). Relatively lower water solubility (solubility = 565 mg/L at 25° C) and higher organic
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carbon partitioning coefficient (Log Koc = 1.786) of aspartame, in comparison with other ASWs,
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explain the preferential partitioning of this compound to sludge and SPM. Further, the lower
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concentrations reported for aspartame in aqueous environmental matrices explain preferential
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sorption of this compound to particulate matter.11,29
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Removal of Artificial Sweeteners from WWTPs. Both saccharin and aspartame were
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significantly removed from WWTPs, with an average removal efficiency of 90.3 and 68.2%,
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respectively (Table 3). The average removal efficiency of saccharin found in our study was
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similar to those reported in Germany (>90%)11 and China (97%).10 Aspartame was not detected
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in effluents of WWTPs in China.10
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Sucralose was not significantly removed from WWTPs ( saccharin and sucralose (0.8%). This study reports
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aspartame in wastewater samples for the first time in the USA. Aspartame and saccharin were
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significantly removed from WWTPs; however, sucralose and acesulfame were removed at
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