Science of the Total Environment

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Mass loading and emission of benzophenone-3 (BP-3) and its derivatives in wastewater treatment plants in New York State, USA

Wei Wang

^a

, Kurunthachalam Kannan

^a,b,

⁎

aWadsworth 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, NY 12201-0509, United States

bBiochemistry Department, Faculty of Science, Experimental Biochemistry Unit, King Fahd Medical Research Center, King Abdulaziz University, Jeddah, Saudi Arabia

H I G H L I G H T S

•Mass loading and fate of benzophenone UVﬁlters were studied in two WWTPs.

•Sorption to sludge accounted for 13.2–

15.7% ofΣBPs' mass reduction

•A negative removal efﬁciency was found for BP-8 and BP-2

•The mass loading ofΣBPs in WWTPs was ~102–276 mg/d/1000 people

•~55–94 mg/d/1000 people ofΣBPs was discharged into the environment from WWTPs.

G R A P H I C A L A B S T R A C T

a b s t r a c t a r t i c l e i n f o

Article history:

Received 7 October 2016

Received in revised form 17 November 2016 Accepted 17 November 2016

Editor: Adrian Covaci

The occurrence of benzophenone type ultra-violet (UV) lightﬁlters, especially 2-hydroxy-4-methoxy benzophenone (2OH-4MeO-BP; BP-3), in aquatic ecosystems is a concern due to the endocrine disruption potential of these chemicals. In this study, mass loading, emission and fate of BP-3 and its derivatives were investigated in two wastewater treatment plants (WWTPs) in the Albany area of New York State, USA. The median concentrations of BP-3 and sum of its four derivatives (ΣBPderivatives) in inﬂuents were 35.6–49.1 and 124–145 ng/L, respectively. The highest concentrations found for BP-3 andΣBPderivativesin sludge (n= 10) were 426–5770 and 856– 5910 ng/g, dry wt, respectively. Sorption to sludge explained for 13.2–15.7% ofΣBPs mass reduction, whereas predominant pathway of BPs removal was biodegradation. The mass loadings (25.7–81.4 and 76.1–194 mg/d/

1000 people) and environmental emissions (10.5–17.5 and 44.5–76.2 mg/d/1000 people) for BP-3 and ΣBPderivativesin WWTPs were estimated. Approximately 11% and 20% of the total production of BP-3 and 2,4- diOH-BP (BP-1) in the U.S. reach WWTPs, while 3% and 15% of the loaded amounts were emitted through WWTP discharges.

Keywords:

Benzophenone-type UVﬁlter Wastewater treatment plant Mass loading

Environmental emission Removal efﬁciency

⁎ Corresponding author at: Wadsworth Center, Empire State Plaza, P.O. Box 509, Albany, NY 12201-0509, United States.

E-mail address:[email protected](K. Kannan).

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Science of the Total Environment

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1. Introduction

Benzophenone-3 (2OH-4MeO-BP; BP-3) has been one of the most widely used ultraviolet (UV) lightﬁlters in sunscreen products and in a variety of cosmetics for over 40 years (Liao and Kannan, 2014; Kim and Choi, 2014). The maximum allowable concentration of BP-3 as an active ingredient in sunscreen products is 6% in the USA (U.S.FDA, 2013). Other benzophenone (BP)-type UVﬁlters, such as benzophenone-1 (2.4-diOH-BP; BP-1), are also used commercially in plastic surface coatings on food packages. Nevertheless, BP-1 is also a major metabolite of BP-3 in humans (Kunisue et al., 2012; Wang and Kannan, 2013; Suzuki et al., 2005). BP-3 can be hydroxylated and/or demethylated to form other metabolic byproducts (Wang and Kannan, 2013; Jeon et al., 2008; Kasichayanula et al., 2005; Nakagawa and Suzuki, 2002). In addition to BP-3, four metabolic derivatives of BP-3, namely BP-1, 4-OH-BP, 2,2′,4,4′-tetraOH-BP (BP-8) and 2,2′- diOH-4-MeO-BP (BP-2), have been reported to occur widely in human urine, serum, and breast milk (Wang and Kannan, 2013; Zhang et al., 2013; Xue et al., 2015).

BP-3 has been reported as an endocrine-disrupting chemical (Fent et al., 2010, Kunz and Fent, 2006a, 2006b). Experimental animal as well as in-vitro studies have suggested that BP-3 can affect reproduction and sex hormone signaling (Suzuki et al., 2005; Kunz and Fent, 2006a, 2006b). In aquatic organisms, BP-3 has been reported to affect reproduction and development (Ozaez et al., 2013; Li, 2012; Sieratowicz et al., 2011).

Some metabolic products of BP-3 are more toxic than that of the parent (BP-3) compound. For example, estrogenic activities of BP-1, BP-8, and 4-OH-BP were reported to be higher than those of BP-3 (Suzuki et al., 2005; Nakagawa and Suzuki, 2002; Molina-Molina et al., 2008;

Morohoshi et al., 2005; Kawamura et al., 2003). Further, BP-1 and BP-3 were shown to be associated with hormone-dependent diseases and ad- verse birth outcomes in humans (Kunisue et al., 2012; Wolff et al., 2008).

The widespread use of BPs has led to the release of these compounds into aquatic ecosystems, such as lakes and rivers (Kim and Choi, 2014).

BP-3 concentrations of up to 125 ng/L have been reported in the surface waters of Lake Hüttnersee in Switzerland (Poiger et al., 2004). Waste- water discharges are the main sources of BPs in the aquatic environment (Loraine and Pettigrove, 2006). Little is known, however, about the occurrence, emission, fate, and removal of BPs in WWTPs. This is theﬁrst study to evaluate mass loading, removal efﬁciency, and environmental emission of BP-3 and its derivatives from U.S. WWTPs.

2. Materials and methods 2.1. Chemicals and reagents

Methanol (HPLC-grade) was purchased from Mallinckrodt Baker (Phillipsburg, NJ), and Milli-Q water was prepared by an ultrapure water system (Barnstead International, Dubuque, IA). BP-3 (98%), 4- OH−BP (98%), 2,4-diOH−BP (99%), 2,2′,4,4′-tetraOH−BP (97%), and 2,2′-diOH−4-MeO-BP (98%) were purchased from Sigma-Aldrich (St. Louis, MO). The physicochemical properties of the target chemicals are presented in Table S1 (Supporting Information [SI]). Mass-labeled

13C-bisphenol A (BPA) (RING-¹³C12, 99%) was purchased from Cambridge Isotope Laboratories (Andover, MA) for use as an internal standard.

2.2. Sample collection and preparation

Details of the collection of wastewater and sludge samples from two WWTPs are provided in Table S2. Briefly, 24-h composite wastewater samples, including raw wastewater (influent), primary-treated wastewater (primary effluent),final effluent, andfinal combined sludge were collected consecutively over a seven-day period, from July 12 to 18, 2013, from two WWTPs in the Albany area of New York State. The composite sampling comprised a collection of individual discrete samples taken at hourly intervals over the sampling period to represent

the average dailyflow. The two plants are denoted as WWTPA(inhabitants served, ~ 15,000) and WWTPB(inhabitants served, ~ 100,000), with treatment capacities of 9.5 and 132 million liters daily (MLD), respectively. Both WWTPs employed activated sludge treatment that in- volved aeration tanks and biological processes. The combined sludge (3.9% solid, determined immediately and gravimetrically) samples (combined sludge produced after primary and secondary treatments) were collected for seven and four consecutive days from WWTPAand WWTPB, respectively. All samples were collected in certified pre- cleaned amber glass jars with Teflon®-faced caps, shipped to the laboratory, and stored in a refrigerator at 4 °C until extraction. The hydraulic retention times at these WWTPs were between 12 and 16 h.

The wastewater samples (100–300 mL) were centrifuged at 5000 xg for 10 min, and the supernatant wasfiltered through a glassfiberfilter (37 mm, pore size 1μm; GE Osmonics, Inc., Minnetonka, MN) to sepa- rate suspended particulate matter (SPM) from the aqueous mixture.

Wastewater samples (100 mL) were spiked with labeled internal standard (20 ng) prior to extraction. The aqueous samples were extracted by passage through Oasis® MCX (3 cm³, 60 mg; Waters, Milford, MA) solid-phase extraction (SPE) cartridges. Prior to use, the cartridges were conditioned with 5 mL of methanol and 5 mL of Milli-Q water, and wastewater samples were loaded at ~ 1 mL/min. Cartridges were allowed to dry for ~30 min under vacuum and then eluted with 9 mL of methanol. The eluents were combined and concentrated to 1 mL under a gentle stream of nitrogen using a TurboVap Evaporator (Zymark, Inc., Hopkinton, MA).

Sludge samples were extracted by solid-liquid extraction followed by a SPE method. Briefly, freeze-dried sludge samples (~ 0.1 g) were spiked with the internal standard (20 ng) and extracted with 5 mL of methanol/water mixture (5:3 v/v) by shaking in an orbital shaker for 60 min. Extracts were centrifuged at 4500 ×gfor 5 min (Eppendorf Cen- trifuge 5804; Hamburg, Germany), supernatant was collected in a poly- propylene (PP) tube, and the extraction was repeated twice. The supernatants were combined and concentrated to ~3 mL under a gentle nitrogen stream and then diluted to 10 mL with Milli-Q water that contained 0.2% formic acid (pH 2.5). The extract was purified by passage through SPE cartridges, as described above. For SPM, the entire content in the pre-weighed glassfiberfilter (obtained from centrifugation and filtration of 100 mL of influents, primary effluents, andfinal effluents) was transferred into a pre-weighed PP tube, freeze-dried, spiked with the internal standard, and extracted as described above for sludge samples. Thefinal volume of the extract was 1 mL, and 10μL of the extract was injected into a high-performance liquid chromatograph-tandem mass spectrometer (HPLC-MS/MS).

2.3. Instrumental analyses

Benzophenones were determined with an Agilent 1260 HPLC (Agilent Technologies, Santa Clara, CA) interfaced with an Applied Biosystems QTRAP 4500 mass spectrometer (ESI-MS/MS; Applied Biosystems, Foster City, CA). A Betasil C18 column (2.1 mm × 100 mm, 5μm; Thermo Electron Corp., Waltham, MA), serially connected to a Jav- elin guard column (Betasil C18, 2.1 mm × 20 mm, 5μm; Thermo Elec- tron Corp.), was used for chromatographic separation. The mobile phase comprised methanol (A) and Milli-Q water (B). The MS/MS parameters were optimized by infusion of individual compounds into the MS through aﬂow injection system (Table S3). A negative ion multiple-reaction-monitoring (MRM) mode was used for the identiﬁcation of target compounds. The MRM transitions of ions monitored are listed in Table S4. Nitrogen was used as both a curtain and a collision gas. Fur- ther details of the instrumental parameters are provided in Table S3.

2.4. Quality assurance and quality control (QA/QC)

Contamination that arises from laboratory materials and solvents was monitored by the analysis of procedural blanks. Trace levels of

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BP-3, 4-OH-BP, BP-1, BP-8, and BP-2 were found in procedural blanks, at concentrations that ranged from 0.02 ng/mL for BP-2 to 0.8 ng/mL for BP-3. Background subtraction was performed in the quantiﬁcation of concentrations of these compounds in samples. With each set of 20 samples analyzed, a procedural blank, two pairs of matrix spike samples (spiked at 20 ng and 40 ng), and a duplicate sample were analyzed.

Quantiﬁcation of BPs was performed by an internal standard method based on the response of¹³C12-BPA. The mean (±SD) recovery of internal standard (¹³C12-BPA) spiked into all samples was 85 (±30) %. Cali- bration curve was prepared by the injection of 10 standards at concentrations that ranged from 0.01 to 100 ng/mL; the regression coef- ﬁcient (R) of all calibration curves wasN0.99. Relative recoveries of BPs spiked into sample matrices ranged from 91.9% for BP-8 to 118% for BP- 2 in sludge, from 81.0% for BP-8 to 86.1% for BP-2 in SPM, and from 83.2%

for BP-3 to 95.0% for BP-8 in wastewater (Table S4). The absolute recoveries of BPs ranged 84–105% in sludge, 99–108% in SPM and 81–122% in wastewater samples. Duplicate analysis (n= 4) of randomly selected samples showed a coefficient of variation of b15% for all target chemicals analyzed. The limits of quantification (LOQs) were 0.50 ng/g dry wt for BP-3 and 4-OH-BP and 0.25 ng/g dry wt for BP-1, BP-8, and BP-2 for sludge and SPM; and the LOQs of BPs in wastewaters ranged from 0.25 to 0.5 ng/L (Table S4). A midpoint calibration standard (dissolved in methanol) was injected as a check for instrumental drift in sensitivity after every 20 samples (variation in instrumental response over time wasb5%), and methanol was injected as a check for carry- over of target analytes from sample to sample (methanol did not con- tain detectable levels of target chemicals). A third extraction was performed for sludge samples to confirm the efficiency of extraction. The concentrations of BPs found in the third extraction (with a mixture of methanol and Milli-Q water at 5:3, v/v) for 15 randomly selected sludge samples wereb1% of the concentrations found in thefirst two extrac- tions, which indicated that the two extraction cycles efficiently extracted the target chemicals from the matrix.

2.5. Data analysis

The fraction of the total mass of BP-3 and its derivatives sorbed to SPM, removal efﬁciency through the treatment processes, mass loadings, environmental emissions through the efﬂuent discharges, and the mass of target compounds that was lost in the WWTP by various transformation processes (Mlost) were calculated using the following equations (Eqs.(1)–(5)), as reported byBletsou et al. (2013),Subedi and Kannan (2014)andWang and Kannan (2016). The fraction of each compound sorbed to SPM was utilized in the estimation of mass loadings and environmental emissions of BPs through WWTPs.

PSPM¼

CSPMMSPM

VW

CSPMMSPM

VW

þCW

100 ð1Þ

REð Þ ¼%

100C_i 100−PSPMi

− 100Ce

100−PSPMe

100Ci

100−PSPMi

100 ð2Þ

ML=1000 people¼CiFinf 100 100−PSPMi

1

population

ð3Þ

E=1000 people¼ ðCeFeffÞ 100 100−PSPMe

þðCsMsÞ

1000 population

1 10⁶

ð4Þ Mlost¼ðFinfCinfÞ−ðFeffCeffÞ−ðMsCsÞ ð5Þ

where PSPMis the fraction of the total mass of BPs sorbed to SPM (%);

CSPMis the concentration of BPs measured in SPM (ng/g dry weight);

M_SPMis the mass of SPM analyzed (g); V_Wis the volume of wastewater (L) used to collect the corresponding MSPM; CWis the concentration of BPs determined in wastewater (ng/L); RE is the removal efficiency (%); C_iis the concentration of BPs determined in wastewater influent (ng/L); Ceis the concentration of BPs determined in wastewater effluent (ng/L); PSPMiis the fraction of the total load of BPs sorbed to SPM (%) in wastewater influent; PSPMeis the fraction of the total load of BPs sorbed to SPM (%) in wastewater effluent; ML is the mass load, an estimated amount of individual BPs introduced into a WWTP through wastewater and SPM per day per 1000 people served (mg/d/1000 people); Finfand F_effare the dailyflows of wastewater influent (L/d) and effluent (L/d), respectively, over a 24-h period; and Cinfand Ceffare the total concentrations (dissolved + particulate) of the target compounds in influent and effluent wastewater (ng/L), respectively. C_sis the concentration of BPs in sludge (ng/g wet weight); people is the number of inhabitants served by the WWTP; and E/1000 is the amount of BPs discharged daily through wastewater effluent, SPM, and sludge per 1000 people (mg/d/

1000 people). Msis the daily mass of sludge produced (g/d wet weight) (average sludge production mass is 928 and 5820 ton/year for WWTPA

and WWTPB, respectively). Median concentrations were used in the cal- culations listed above for the samples collected on seven consecutive days in each WWTP. Concentrations below the LOQ were substituted with a value equal to LOQ divided by the square root of 2 for the calcu- lation of geometric mean (GM).

3. Results and discussion

3.1. BP-3 and its derivatives in wastewater

BP-3 was found in all wastewater inﬂuents (detection rate [DR]:

100%) from both WWTPs, which reiterates the widespread release of this compound from various sources including personal care products (Table 1) (Liao and Kannan, 2014; Kim and Choi, 2014). 4-OH-BP, however, was determined to be the most abundant BP (with highest concentrations) found in the wastewater influent, at median concentrations of 77.2 and 76.5 ng/L in WWTPAand WWTPB, respectively; the concentration of 4-OH-BP in influents was followed, in decreasing order, by BP-3 (35.6–49.1 ng/L), BP-1 (25.3–26.2 ng/L) and BP-2 (14.5–15.4 ng/L). The measured concentrations of BP-3 in influents in our study were similar to the previously reported concentration range of a few ng/L to a few hundred ng/L in Italy and Spain (Rodil et al., 2008; Magi et al., 2013), where the predominance of BP-3 in wastewater has been reported; but lower than the reported median concentrations of 6240–6870 ng/L found for influents from a WWTP in California, USA (Loraine and Pettigrove, 2006). No earlier studies have measured 4-OH-BP, BP-1, or BP-2 in wastewater samples.

The derivatives of BP-3, 4-OH-BP, BP-1, and BP-2 were detected in 100% of influent samples, whereas BP-8 was found in 86% of influent samples. The ratio of 4-OH-BP/BP-1 wasb0.1 in urine from the U.S. population (Kunisue et al., 2012; Wang and Kannan, 2013); whereas this ratio wasN3 in wastewater influents. 4-OH-BP was the primary deriva- tive of BP-3 in influents (accounting forN66% of the total BP concentrations), which suggests the existence of multiple sources for this compound (apart from human excretion), including transformation of BP-3 to 4-OH-BP in the sewerage system. Other sources of 4-OH-BP (e.g., degradation of alkylphenols) are expected to be present in sewage.

Among the four BP derivatives, BP-8 is the hydroxylated product, whereas 4-OH-BP, BP-1, and BP-2 are the demethylated products, both of which are Phase I metabolites of BP-3 (Nakagawa and Suzuki, 2002; Okereke et al., 1993, 1994). The proﬁles of BP derivatives in wastewater inﬂuents suggest that demethylation of BP-3 is a major transformation pathway for this compound (Wang and Kannan, 2013). Some BPs, such as BP-1, also can originate from the direct use of these compounds in personal care products. However, the lower

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concentrations of BP-1 than BP-3 in wastewater can be attributed to its faster removal/transformation and lesser usage of this compound (Kim and Choi, 2014).

3.2. BP-3 and its derivatives in sludge and suspended particulate matter

Very few studies have reported on the occurrence of BP-3 and its derivatives in sludge and SPM, with limited data on BPs bound to particulate matter. BP-3 has been reported as the most abundant BP in sludge in previous studies (Kim and Choi, 2014; Zhang et al., 2011). However, BP-1 was found at the highest concentration in sludge from both WWTPAand WWTPB, with median values of 1370 and 1510 ng/g dry wt, respectively, followed by BP-3 (1200 and 1290 ng/g, dry wt), which suggests varied formation and use-patterns of BPs in different countries/communities. The differences in the distribution profile (individual BP toΣBP) between sludge and wastewater (mass/mass comparison) suggest variations in the partitioning behavior (partitioning coefficient to solid matter) of these compounds (Fig. S1, Table S1). BP- 1 partitioned more preferentially to sludge (58%) than did 4-OH-BP (0.3%), BP-8 (1.2%), or BP-2 (0.2%). The distribution of BP-3 between influent wastewater (34%) and sludge (40%) was similar. BP-3 is moder- ately hydrophobic and is expected to partition preferentially toward suspended particles and sludge (Kim and Choi, 2014). 4-OH-BP and BP-2 were enriched in influent wastewater, with low concentrations in sludge (6.40–23.3 and 1.03–31.2 ng/g dry wt).

The measured concentrations of BP-3 and BP-1 (n= 10) in sludge were significantly (one-way ANOVA,pb0.05) higher than those reported for WWTPs in Northeastern China (Zhang et al., 2011). A significant (pb0.05) correlation was found for all BPs, except for BP-2, in sludge from the two WWTPs (Table S6), which can imply a common source for these compounds. Further, the concentrations ofΣBPderivatives(856– 4530 ng/g and 1460–5910 ng/g, dry wt for WWTPAand WWTPB) were significantly higher than BP-3 concentrations in sludge, with median values of 1450 and 1570 ng/g, dry wt, in WWTP_Aand WWTP_B, respectively, suggesting potential degradation/transformation. Considering the high estrogenic activities of metabolites of BP-3 (Kawamura et al., 2003), the high concentrations found in sludge are a concern, as sludge is commonly used as an organic amendment in farmlands.

This is theﬁrst report to document the occurrence of BP-3 and its derivatives in SPM. BP-3 was found in 78.6% of the inﬂuent SPM samples, at a median concentration of 2240 (range: ND–30,100) and 878 (range: ND–27,800) ng/g dry wt, for WWTPAand WWTPB, respectively.

However, the highest concentrations were found for BP-8 and BP-2, with respective median values of 6250 and 3500 ng/g dry wt, for WWTPA, and 2740 and 4140 ng/g dry wt, for WWTPB(Table S5). The

median concentrations of 4-OH-BP in SPM ranged from 100 to 1510 ng/g, dry wt, while the lowest concentrations were found for BP- 1 (ND–6100 ng/g; DR: 28.6%). The fraction of BP-3 and its derivatives bound to SPM was calculated based on the measured concentrations in the aqueous fraction and SPM, mass of SPM, and corresponding volume of wastewater (Eq.(1)). The fraction of the total mass of BPs sorbed to influent SPM, on average, was, in decreasing order, BP-8 (96.8%)NBP- 2 (33.2%)NBP-3 (15.1%)N4-OH-BP (2.87%)NBP-1 (0.82%). The differences in the order of partitioning of BPs in sludge and SPM indicate the influence of microbial activity and organic matter content in these two solid matrices. Therefore, estimation of mass loadings of BP-3 and its derivatives based only on concentrations in the dissolved fraction can significantly underestimate the total load.

3.3. Removal of benzophenones from WWTPs

This is thefirst study to report removal efficiencies (that included measurement of both aqueous and SPM fractions) of BP-3 and its derivatives in WWTPs. The highest median removal efficiency was found for BP-3 (86.2% to 91.7%), followed by 4-OH-BP (86.7% to 90.1%), BP-1 (61.0% to 94.1%), BP-2 (−45.9% to−61.3%), and BP-8 (−584% to− 403%). The negative removal rates for BP-8 and BP-2 were due to significantly increased masses of these compounds in effluents, possibly via transformation or degradation of precursor compounds, including BP- 3, during the treatment processes. The increased loadings of BPs in effluents, contributed predominantly by BP-8 and BP-2 adsorbed onto particulates, suggest the existence of both hydroxylation and demethylation reactions in the treatment processes. However, real removal (Mlost%) efficiencies (i.e. without taking into account of sorption to sludge) were calculated based on the daily massflows of BPs in influents, effluents and sludge (as shown in Eq.(5)). The removal efficiencies (Mlost%) were 62.6%, 94.0%, 32.0%,−32.5% and 86.5% for BP-3, 4-OH- BP, BP-1, BP-8 and BP-2, respectively (Table 2). The average removal (or transformation) rates of BP-3 derivatives (78.1%) were similar to the removal rates found for BP-3 (78.8%).

3.4. Mass loadings and environmental emission of benzophenones through WWTPs

The total mass of BPs that enter WWTPs was calculated based on the measured concentrations in influents, average dailyflow of influents, and the population served by the WWTP. The mass loadings of BP-3 in WWTPA(25.7 mg/d/1000 people), which serves a smaller population (~15000), were 3 times lower than those of WWTPB(81.4 mg/d/1000 people) (Table 2), which serves a larger population (~ 100,000). The Table 1

Concentrations of benzophenones in wastewater (aqueous plus SPM fractions) and sludge from two centralized wastewater treatment plants (WWTPs) in Albany area, New York, USA, in July 2013.

Water (ng/L) Sludge (ng/g dry wt)

WWTPA WWTPB WWTPA WWTPB

Influent Primary effluent Final effluent Influent Primary effluent Final effluent

Median/mean range Median/mean range Median/mean range

BP-3 35.6/45.5 39.5/104 bLOQ/2.24 49.1/94.9 35.0/33.2 bLOQ/5.17 1200/1260 1290/2560

17.0–125 bLOQ-519 bLOQ-11.6 29.9–295 22.9–41.4 bLOQ-32.7 426–2550 610–5770

4-OH-BP 77.2/68.8 22.4/51.1 4.74/4.80 76.5/73.6 12.8/15.7 4.25/4.72 12.4/12.6 8.49/12.7

15.7–103 1.60–109 3.01–8.26 28.5–106 1.72–35.5 1.20–9.15 7.84–17.2 6.40–23.3

BP-1 25.3/25.5 7.17/16.0 2.40/2.59 26.2/46.2 5.14/12.6 1.36/1.84 1370/2200 1510/2900

1.56–65.7 0.08–52.6 0.36–6.54 8.84–122 bLOQ-38.6 0.14–4.89 798–4470 1370–5810

BP-8 2.75/2.93 0.81/3.04 2.15/2.24 1.01/1.80 1.58/1.73 1.02/2.57 41.8/41.5 68.1/63.8

bLOQ-8.29 bLOQ-8.50 bLOQ-5.67 bLOQ-5.43 bLOQ-3.89 bLOQ-11.4 13.1–62.5 54.1–69.3

BP-2 14.5/36.7 5.75/14.1 3.77/8.78 15.4/23.8 3.36/12.1 1.08/3.56 2.66/10.3 7.00/7.39

3.81–123 0.94–41.3 1.34–29.7 10.2–67.7 bLOQ-47.6 bLOQ-17.8 1.03–31.2 5.19–9.98

ΣBPderivatives 145/134 32.4/84.2 16.7/18.4 124/145 45.9/42.2 6.86/12.7 1450/2260 1570/2980

24.8–227 6.51–196 6.89–43.1 98.0–241 5.13–84.7 5.40–28.0 856–4530 1460–5910

ΣBPs 322/313 109/273 33.9/39.1 405/386 123/118 14.2/30.6 3370/3520 6520/5540

85.3–502 16.8–872 14.3–97.8 251–511 35.7–207 11.3–88.8 1970–4990 2870–7230

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mass loadings of BP-3 derivatives in both WWTPs (76.1 mg/d/1000 for WWTPAand 194 mg/d/1000 for WWTPB) were 2–3 times higher than those of BP-3, with the highest mass loadings found for 4-OH-BP (33.1; 61.8 mg/d/1000) and BP-2 (23.5; 86.4 mg/d/1000) in both the WWTPs. In general, the total BP mass loading for the sum of benzophenones (ΣBPs) was estimated at 102 and 276 mg/d/1000 people for WWTPAand WWTPB, respectively. The high mass loading of BP-2 suggests degradation of BP-3 or direct input of this compound.

The total mass of BP-3 and its derivatives discharged through WWTP effluents and sewage sludge was calculated based on the concentrations measured in effluents, SPM, and sludge as well as by the dailyflow rate of effluents, total sludge production rate, and the population served by the WWTPs. The emission rates of BP-2 were the highest (15.9–47.6 mg/day/1000 people), followed by BP-1 (16.2–20.0 mg/day/1000 people) and BP-3 (10.5–17.5 mg/day/1000 people), which can be explained by high loadings and low removal rates (Table 2). Although there was considerable removal of BP-3 and its derivatives, the emission of sum of all benzophenones (ΣBPs) analyzed in this study from WWTPs was

~55.0–93.7 mg/d/1000 people. The predominance of BP-2 in emission estimates from WWTPs was different from the profile found for loading (predominated by BP-3). These differences in BP profiles can be explained by varied removal efficiencies and transformation processes in WWTPs. The mass loading and environmental emission ofΣBPs were comparable to the loading and emission estimates determined for as- partame (artificial sweetener) and parent parabens (preservatives) in the same WWTPs from the Albany area (Subedi and Kannan, 2014;

Wang and Kannan, 2016).

3.5. Fate of benzophenones in WWTPs

We estimated the nationwide environmental loading of target chemicals through wastewater treatment plants based on WWTP loading rate and U.S. population (315 million in 2013). The estimated mass loadings through WWTPs in the USA were 6.1 ton/year and 3.0 ton/year for BP-3 and BP-1, respectively. The combined production and import volume of BP-3 (CAS No. 131–57-7) was estimated in the range of 45 to 227 ton/year with the reported value as 54 ton/year, and that of BP- 1 (CAS No. 131–56-6) was ~14 ton/year in the USA in 2011 (U.S. EPA, 2016); it can be estimated that WWTP based mass loading of BP-3 and BP-1 account for approximately 11.4% and 20.4% of the total production. The environmental emission via WWTP accounted for 3.0%

and 14.5% of the annual production of BP-3 and BP-1, respectively. An- nual emissions of BP-3 and BP-1 estimated through WWTP discharges were 1.6 ton/year and 2.1 ton/year, respectively.

Few studies have reported the mass balance analysis of BPs to eluci- date the fate of these compounds in WWTPs. Based on the daily mass flows of BPs, mass loadings substantially decreased from influent to final effluent (Fig. S2). Sorption to sludge explained for 13.2–15.7% of ΣBPsmass reduction, whereas 75.2–82.5% ofΣBPswere transformed/

lost during the treatment processes. Therefore, the predominant pathway of BPs removal was considered to be biodegradation and

volatilization. The mass out was estimated at 0.19–1.32 g/d for BPs, which was 4.29–9.14% ofΣBPsestimated to enter the plants (i.e., mass in). The removal mechanisms of BPs in WWTPs are expected to vary, de- pending on the chemical structure, sorption potential, treatment methods, and season, among other factors. The ratio of BP derivatives to BP-3 increased from 0.46 for mass in to 0.53 for mass out at WWTPA, whereas that for WWTPBincreased from 0.29 to 0.52, which suggested that the parent compounds, such as BP-3, are transformed to metabolites during the WWTP processes and that the metabolites are resistant to further degradation. The differences in the proportions of BPs found in the inﬂuents of WWTPs, suggested varied sources for these compounds (~ 5% industry waste for WWTPA and ~ 25% for WWTPB). The ratio of derivatives toΣBPswas higher in sludge from WWTP_A(0.43) than from WWTP_B(0.24), possibly due to the higher input of BP-3 in WWTPBthat serves a larger population. Further inves- tigations are needed to identify and quantify the transformation byproducts of BP-3 in WWTPs.

No significant correlations were found among BP-3 derivatives in influent wastewater samples, which indicated the existence of multiple sources. In thefinal effluent, a significant correlation (pb0.05) was found for BP-2 & BP-1, BP-3 & BP-8 and BP-3 & 4-OH-BP. The correlation between BP-3 and BP-8 in primary andfinal effluent as well as sludge suggests that BP-3 may be transformed to BP-8 in WWTP; however, other precursors or sources contribute to BP-2 infinal effluent and sludge. The average composition profiles of BPs found in various types of samples collected from WWTPs are presented inFig. 1. BP-3 and 4- OH-BP were the largest contributors toΣBPsin aqueous phase of influents, primary effluents, andfinal effluents; BP-3 and BP-1 collectively accounted forN90% ofΣBPsin sludge. However, BP profiles in SPM were featured by the predominance of BP-8 and BP-2, with the contribution of BP-3 decreased from influent tofinal effluent. The varied com- positional profiles of BPs among several matrices in WWTPs suggest different absorption potentials and transformation rates.

Although this is theﬁrst study to report the fate of BPs in WWTPs, our study has limitations. Our extraction time exceeded 24 h from the time of sample collection and microbial transformation could occur during storage and transport. However, our analytical methods have been validated and the information presented in the study took into consid- eration of potential artefacts and confounders.

4. Conclusions

In summary, mass loadings, removal efficiencies, discharge and fate of BP-3 and its derivatives were determined in two WWTPs in the Alba- ny area of New York State. This study confirmed for thefirst time the occurrence of four degradation products of BP-3 (BP-1, 4-OH-BP, BP-8, and BP-2) that have estrogenic toxicity in wastewater and sludge samples.

Sorption to sludge explained for 13.2–15.7% ofΣBPs mass reduction, whereas predominant pathway of BPs removal was biodegradation. A negative removal efﬁciency (on the basis of both aqueous and SPM fractions) was found for BP-8 (−584% to−403%) and BP-2, suggesting that Table 2

Mass loading, environmental emission, and removal efﬁciency of benzophenones in two WWTPs from New York state, USA.

Analyte Mass load

(mg/d/1000 people)

Emission via WWTPs (mg/d/1000 people)

Average % removal I^a Average % removal II^b

WWTPA WWTPB WWTPA WWTPB WWTPA WWTPB WWTPA WWTPB

BP-3 25.7 81.4 10.5 17.5 91.7 ± 12.0 86.2 ± 0.97 46.8 78.5

4-OH-BP 33.1 61.8 2.65 4.24 86.7 ± 17.2 90.1 ± 4.23 93.6 94.4

BP-1 11.9 38.8 16.2 20.0 61.0 ± 3.60 94.1 ± 6.46 11.6 52.4

BP-8 7.50 7.21 9.75 4.26 −584 ± 257 −403 ± 187 5.72 −70.6

BP-2 23.5 86.4 15.9 47.6 −45.9 ± 33.2 −61.3 ± 15.2 80.5 92.5

ΣBPderivatives 76.1 194 44.5 76.2 74.7 81.5

ΣBPs 102 276 55.0 93.7 75.2 82.5

aRemoval efficiency calculated based on the BPs determined in influent water, effluent water and the fraction determined in SPM.

b Removal efficiency calculated based on the daily massflow of BPs in influent water (including SPM), effluent water and sludge.

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they are formed from precursors in the wastewater treatment processes. Considerable variations in the proﬁles BPs among wastewater, SPM, and sludge samples suggested the existence of multiple sources, differences in adsorption, and transformation rates in the wastewater treatment processes. The median daily loadings ofΣBPderivativeswere 2–3 times higher than that of BP-3 itself; consequently, the discharge rates of BP-3 derivatives wereN4 times higher than that of BP-3. The high emission rate for BP-2 was calculated based on the discharge of WWTP efﬂuents and sludge disposal. WWTP based mass loading of BP-3 and BP-1 account for approximately 11.4% and 20.4% of the total production in the U.S.; the environmental emission via WWTP account for 3.0% and 14.5% of the annual production of BP-3 and BP-1, respectively.

Notes

The authors declare no competingﬁnancial interests.

Acknowledgments

The authors would like to thank the WWTP facilities, Mr. Jingchuan Xue for assistance with the sample collection.

Appendix A. Supplementary Material

Supplementary data to this article can be found online athttp://dx.

doi.org/10.1016/j.scitotenv.2016.11.124.

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