Occurrence of PPCPs at a Wastewater Treatment Plantand in Soil and Groundwater at a Land Application Site

Adcharee Karnjanapiboonwong & Jamie G. Suski &Ankit A. Shah & Qingsong Cai & Audra N. Morse &

Todd A. Anderson

Received: 29 March 2010 /Accepted: 25 June 2010 /Published online: 10 July 2010# Springer Science+Business Media B.V. 2010

Abstract Pharmaceuticals and personal care products(PPCPs) can reach soil and aquatic environmentsthrough land application of wastewater effluent andagricultural runoff. The objective of this research was toassess the fate of PPCPs at field scale. PPCPs weremeasured systematically in a wastewater treatment plant(WWTP), and in soil and groundwater receiving treatedeffluent from theWWTP. A land application site inWestTexas was used as the study site; it has received treatedwastewater effluent from the WWTP for more than70 years in order to remove additional nutrients andirrigate non-edible crops. Target compounds (estrone,17β-estradiol, estriol, 17α-ethynylestradiol, triclosan,caffeine, ibuprofen, and ciprofloxacin) in wastewater,sewage sludge, soil, and groundwater were determined

using HPLC/UV with qualitative confirmatory analysesusing GC/MS. Samples were collected quarterly over12 months for wastewater and sludge samples and over9 months for soil and groundwater samples. Resultsindicated that concentrations of PPCPs in wastewaterinfluent, effluent, sludge solid phase, and sludge liquidphase were in the range of non-detected (ND)-183μg/L,ND-83 μg/L, ND-19 μg/g, and ND-50 μg/L, respec-tively. Concentrations in soil and groundwater sampleswere in the range of ND-319 ng/g and ND-1,745 μg/L,respectively. GC/MS confirmation data were consistentwith the results of HPLC/UV analyses. Overall, dataindicate that PPCPs in the wastewater effluent from theWWTP transport both vertically and horizontally in thesoil, and eventually reach groundwater following landapplication of the effluent.

Keywords Pharmaceuticals andpersonal care products(PPCPs) .Wastewater . Sludge . Groundwater . Landapplication . Soil contamination

1 Introduction

Pharmaceuticals and personal care products (PPCPs)have been identified in the environment and recentstudies have focused on their potential ecotoxicity(Daughton and Ternes 1999). Some natural estrogens,such as estriol, estradiol, and estrone are considered tobe potent endocrine disruptors (Gross et al. 2004;

Water Air Soil Pollut (2011) 216:257–273DOI 10.1007/s11270-010-0532-8

A. Karnjanapiboonwong :A. A. Shah :Q. Cai :T. A. Anderson (*)The Institute of Environmental and Human Health(TIEHH), Department of Environmental Toxicology,Texas Tech University,41163, Lubbock, TX 79409-1163, USAe-mail: todd.anderson@tiehh.ttu.edu

J. G. SuskiDepartment of Biological Sciences, Texas Tech University,43131, Lubbock, TX 79409-3131, USA

A. N. MorseDepartment of Civil and Environmental Engineering,Texas Tech University,41023, Lubbock, TX 79409-1023, USA

Ying et al. 2004). However, the fate and persistenceof these compounds are still unclear (Daughton andTernes 1999; Kolpin et al. 2002; Gross et al. 2004;Ankley et al. 2007). Other antimicrobial compounds,such as the triclosan used in many personal careproducts, are believed to lead to the development ofantibiotic resistance and are considered as persistentchemicals in the environment (Ying and Kookana2007). These PPCPs transport to municipal wastewatertreatment plants (WWTPs) and eventually are dis-charged into aquatic environments or persist in surfacewater, groundwater, and soil (Chu and Metcalfe 2007;Allaire et al. 2006).

Hundreds of tons of PPCPs are estimated to beproduced and consumed annually in developedcountries (Scheytt et al. 2006; Polar 2007). The effluentfrom WWTPs is the primary route of human PPCPsbeing introduced into the environment. Since waste-water treatment processes are designed to removepathogens and nutrients from sewage, PPCPs can onlybe incidentally removed and the elimination is variable(Daughton and Ternes 1999; Heberer 2002a). PPCPsconsumed by humans enter the wastewater system indifferent manners; they can be excreted completelyunmetabolized, rinsed off of the body, or disposed asunused medications. Some PPCPs are conjugated inthe body prior to excretion. These conjugated forms areoften broken down during the wastewater treatmentprocess and can be transformed back to the parentcompound. PPCPs are not typically persistent, but areconstantly released to receiving environments and havethe potential for continual environmental entry(Heberer 2002a; Kümmerer 2004; Gielen et al. 2009).Several studies have determined that PPCPs exist ineffluents in the range of high ng/L to low μg/Lconcentrations, and are present in stream surveys in theUnited States (Gross et al. 2004; Haggard et al. 2006;Waltman et al. 2006; Glassmeyer et al. 2008).Although PPCPs occur at relatively low concentra-tions, their continual long-term release may result insignificant environmental concentrations.

Effluent from WWTPs is increasingly reused toirrigate crops and public areas in arid regions in theUnited States and other countries to reduce the demandon water supplies (Pedersen et al. 2005; Kinney et al.2006). Wastewater effluent is also applied to land fortertiary treatment as the effluent moves through thenatural filter provided by soil and plants (Davis andCornwell 1998; Overcash et al. 2005). Application to

land is considered the oldest method for treatment anddisposal of wastes. There are around 600 communitiesin the United States reusing effluent from municipalWWTPs for surface irrigation (Davis and Cornwell1998). The application of wastewater to land is also aroute of PPCP transfer to soil (Oppel et al. 2004).Various PPCPs in the effluent can sorb to soil once thesoil is exposed to these compounds (Casey et al. 2005;Drillia et al. 2005; Hildebrand et al. 2006). They canalso be transported from the soil to other aquaticsystems and groundwater, the extent of which isdependent on various factors including the solubility,sorption behavior, and persistence of the contaminantas well as climatic conditions and physicochemicalproperties of the soil (Boxall 2008). Since PPCPsremaining in treated wastewater can leach to ground-water supplies through runoff and subsurface transport,concerns about these compounds in effluent enteringpotential drinking water resources and the environmentare increasing. There are several reports indicating thatPPCPs such as estrone, ibuprofen, diclofenac, andchlofibric acid can be detected in groundwater anddrinking water (Ternes et al. 2001; Heberer 2002b;Rodriguez-Mozaz et al. 2004).

The objective of this work was to determine the fateof PPCPs at field scale. PPCPs were measuredsystematically in liquid and sludge lines at a WWTP,and in soil and groundwater receiving treated effluentfrom the WWTP. The occurrence of target PPCPs wasevaluated to assess PPCP transfer potential from aWWTP to soil and groundwater. The unique study sitewas a wastewater land application area used for nutrientremoval and non-edible crop production. This landapplication site (LAS) has received treated wastewatereffluent for more than 70 years, and was therefore anideal site to determine the long-term fate of PPCPs in theenvironment. Target PPCPs included estrone (E1), 17β-estradiol (E2), estriol (E3), 17α-ethynyl estradiol (EE2),caffeine, triclosan, ibuprofen, and ciprofloxacin.

2 Materials and Methods

2.1 Study Area

The water reclamation plant (WRP) was located in aWest Texas community, and served as the test facilityfor the fate of PPCPs in a full-scale WWTP.Wastewater is delivered to the plant through 900

258 Water Air Soil Pollut (2011) 216:257–273

miles of collection lines and 21 lift stations. Thecommunity’s water consumers can be characterized asresidential (85%), small commercial (10%), municipal(4%), and other user classes (1%) include industrial,schools, wholesale, and irrigation. The WRP treatsapproximately 21 million gallons of wastewater perday and has an average daily flow design capacity of31.5 million gallons. There are three process streamsfor the plant, including one biotower process and twoactivated sludge processes (Fig. 1). Primary treatmentof the influent consists of screening and grit removal.After primary treatment, the flow streams are splitbefore secondary treatment. The plant contains acti-vated sludge basins in Plants 3 and 4 for secondarybiological treatment. Plant 2 uses biotowers forsecondary treatment. Without tertiary removal, treatedeffluent is reused (nearly two-thirds of the wastewater

produced each day) through agricultural irrigation onland application sites and as industrial cooling water.Some effluent is also discharged to a stream. Sludgefrom secondary treatment is thickened, digested inanaerobic digesters, dewatered, and landfilled.

The LAS was 6,000 acres of irrigated farmlandused by the city as a site of secondary-treatedwastewater effluent application. The LAS is seededwith grasses, cotton, and legume plant species thatabsorb and utilize the nitrogen present in the effluent.The site has been in use for this purpose since 1937,starting with 200 acres; additional land was purchasedover time. Since that time, monitoring wells havebeen constructed to assess the groundwater quality atvarious locations; nitrate has been of particularinterest. Pivot irrigation systems are employed toapply the effluent to 31 treatment plots corresponding

Bar Screens*Influent Grit Chamber

PrimaryClarifiers

PrimaryClarifiers

PrimaryClarifiers

Plant 2 Plant 3

Plant 4

Biotowers Aeration* Basin

Aeration*Basin

Secondary Clarifiers

Secondary Clarifiers

Secondary Clarifiers

Effluent* Station II

Chlorine* Contact

Filters

Effluent* Station I

Recirculation

Solid returns

Solid returns

Fig. 1 Process schematic ofthe WRP. Asterisk (*) indi-cates sampling locations

Water Air Soil Pollut (2011) 216:257–273 259

to 2,538 total acreage. A lined storage reservoir (412million gallons) enables the city to store and distributetreated effluent to the treatment plots as needed.Approximately 13 million gallons of treated effluentfrom the WRP are applied daily on treatment plots.Farming and cattle grazing at the LAS help thecommunity return some revenues by reducing boththe expense of wastewater disposal and the need todischarge the effluent into streams or lakes. Prairiedogs occupy approximately 700 acres of the 6,000-acre site; however, only about 30% of the occupiedarea is under center pivots. The LAS soils areclassified as slightly alkaline loams with more than40% sand and low organic matter (<2%).

2.2 Sample Collection

Wastewater and sludge Grab samples of wastewaterand sludge were collected from various samplingpoints at the WRP quarterly from December, 2008to September, 2009 to determine the fate of targetPPCPs in the plant. The WRP contains threeindependent process trains referred to as Plants 2,3, and 4; therefore, samples were collected fromPlants 3 and 4 in order to compare these plants,which attain different effluent water quality. Approxi-mately 50% of the plant flow is sent to Plant 4.Wastewater samples were collected at the bar rack,aeration basin, chlorine contact chamber, and effluentstation. Sludge samples were collected from feedsludge, which was the waste sludge from secondarytreatment, and the anaerobic digester. All samples werecollected in 1-L amber jars, stored on ice duringtransport to the laboratory, and refrigerated at 4°C untilextraction.

Groundwater and soil Groundwater and soil sampleswere collected at the LAS to determine whether PPCPsaccumulate in soil and/or are transported to groundwater.There were four sampling points named after themonitoring well codes: CL-11, CL-29, CL-43, and CL-48. CL-29 and CL-48were wells located outside the areaof pivot irrigation, while CL-11 and CL-43 were undercenter pivots. At these sampling points, both groundwa-ter and soil samples were collected quarterly on the sameday fromMarch, 2009 to September, 2009. Groundwatersampleswere collected from a tap above thewells, storedin 1-L amber glass bottles, and refrigerated at 4°C untilprocessed prior to analysis. Soil cores were collected

from each sampling point at a depth of 0–30 in. to covertarget depths of 0–6 in., 12–18 in., and 24–30 in. A soilcorer (4.5 cm diameter) was used. Soil cores were storedat 4°C.

2.3 Chemicals and Reagents

Anhydrous caffeine, ibuprofen (purity>99%), estrogencompounds, including E1 (purity >99%), E2 (purity>98%), E3 (purity >99%), EE2 (purity >98%), β-estradiol-17acetate (purity >99%), and triethylamine(purity >99%) were obtained from Sigma-Aldrich (St.Louis, MO). Triclosan (purity >97%) and ciprofloxacin(purity >98%) were purchased from Fluka ChemieGmbH (Buchs, Switzerland). Relevant chemical prop-erties of the test compounds are shown in Table 1.HPLC-grade acetonitrile, pesticide-grade methanol,95% EDTA disodium salt dihydrate (Na2EDTA·2H2O),and HPLC-grade glacial acetic acid were obtainedfrom Fisher Scientific (Fair Lawn, NJ). Formic acid(purity >98%) was obtained from Acros Organic (NJ,USA) and HPLC-grade phosphoric acid (purity>85%)was purchased from EMD Chemical (Gibbstown, NJ).Reagent-grade potassium dihydrogen phosphate(KH2PO4) was from J.T. Baker (Phillipsburg, NJ).Ultrapure water (>18 MΩ) was supplied by a Barn-stead NANOpure infinity ultrapure water system(Dubuque, IA). Standard solutions of test compoundswere prepared in 1:1 (v/v) acetonitrile: water forestrogens, 100% acetonitrile for caffeine, triclosan,and ibuprofen, and 10% acetic acid for ciprofloxacin.

2.4 Sample Preparation

Wastewater and Groundwater Wastewater andgroundwater samples were first filtered through 10-cm P5 filter paper (Fisher Scientific, PA, USA) toremove suspended solids. Solid-phase extraction(SPE) was applied for target PPCPs. For estrogens(E1, E2, E3, and EE2), caffeine, triclosan andibuprofen, the extraction procedure was based onmethods published previously (Kvanli et al. 2008).β-estradiol-17acetate (EA) was used as an internalstandard for recovery purposes. Two hundred milli-liters of wastewater or 500 mL of groundwater samplewas passed through a C18 SPE cartridge (HoneywellBurdick & Jackson, MI, USA), which was firstconditioned with 3 mL of acetonitrile followed by

260 Water Air Soil Pollut (2011) 216:257–273

3 mL of Milli-Q water. Samples were evacuatedthrough SPE cartridges at a flow rate <5 mL·min−1

and were subsequently eluted with 3×1 mL ofacetonitrile. The eluate was then analyzed by HPLC/UV. The recovery of this extraction method for bothclean (Milli-Q) water and wastewater matrices isshown in Table 2. The method applied also providedadequate detection limits (determined using US EPA2000 guidelines; see Table 3).

For ciprofloxacin, the extraction procedure was basedon methods previously reported by Christian et al.(2003) and Lee et al. (2007). Two hundred milliliters of

filtered sample was acidified to pH 3.5 with glacialacetic acid, and then extracted by using a 1-g OasisHLB cartridge (Waters, Milford, MA, USA), whichwas conditioned with 5 mL of methanol followed by10 mL of water at pH 3.5. Samples were passedthrough the cartridge at a flow rate of 10–15 mL·min−1.Washing was performed using 30 mL of water at pH3.5 and 5 mL methanol. The elution was conductedusing 10 mL of 20/75/5 (v/v/v) methanol/acetonitrile/formic acid. The eluate was then evaporated to about500 μL under nitrogen, brought to 2 mL withacetonitrile, and analyzed by HPLC/UV. The recoveryof this extraction method for ciprofloxacin in both

Table 1 Relevant chemical properties of the test compounds

Compound Water solubility (mg/L at 20°C) log Kow Kd (mL/g) Vapor pressure (mmHg)

Estrone (E1) 13a 2.95b 68c 1.41×10−7d

17β-estradiol (E2) 13a 3.86b 116c 1.26×10−8d

Estriol (E3) 13a 2.45b 8.6c 1.97×10−10d

17α-ethynylestradiol (EE2) 4.8a 3.67b 176c 2.64×10−9d

Triclosan 10d 4.76d 257c 6.45×10−7d

Caffeine 2.16×104d,e −0.07d 19c 15d

Ibuprofen 21d 3.97d 1.69f 1.86×10−4d

Ciprofloxacin 3.00×104d 0.28d 61–64g 1.65×10−12d

a Ying and Kookana (2005)b Machatha and Yalkowsky (2005)c Karnjanapiboonwong et al. (2010)d National Library of Medicine Toxnet (http://toxnet.nlm.nih.gov)e At 25°Cf Scheytt et al. (2005)g Uslu et al. (2008)

Compound Mean recovery (%)±SE

Milli-Q watera Wastewatera Sludgeb Soilb

E1 106±1.1 102±5.7 51±3.2 98±0.2

E2 110±7.9 106±0.5 39±4.2 95±1.7

E3 105±3.9 106±2.7 38±0.4 104±1.4

EE2 114±5.1 106±5.4 45±6.6 100±0.9

EA 91±11.9 106±3.3 28±3.8 99±1.6

Caffeine 84±5.1 102±4.1 72±2.5 91±0.7

Triclosan 83±1.0 79±0.4 80±4.7 93±1.0

Ibuprofen 101±5.0 75±5.8 72±2.2 97±0.5

Ciprofloxacin 89±7.0 77±3.8 82±1.0 28±7.1

Table 2 The recoveryobtained from extractionand HPLC/UV analysis ap-plied to target PPCPs indifferent types of matrices(n=3)

a Prepared by spiking eachcompound at 100 μg/L intosampleb Prepared by spiking eachcompound at 0.1 μg/g dryweight into sample

Water Air Soil Pollut (2011) 216:257–273 261

clean water and wastewater matrices is shown inTable 2. Detection limits for ciprofloxacin are alsopresented in Table 3.

Sludge and Soil Sludge samples (200 mL) werefiltered by using P5 filter paper to separate solidphase from liquid. Filtrate was extracted using thesame procedures as those for wastewater samples.The solid phase of sludge (or soil) samples was airdried and the dry weight was recorded. In 250-mLPTFE centrifuge bottles, the dried samples wereextracted (for the determination of estrogens, caffeine,triclosan, and ibuprofen) with acetonitrile. EA wasused as an internal standard. The samples wereagitated on an orbital shaker for 2 h and centrifugedfor 10 min (4,000 rpm). The supernatant wascollected, evaporated to about 500 μL under nitrogen,and brought to 3 mL with acetonitrile.

The extraction of ciprofloxacin from sludge or soilwas conducted based on a method reported by Uslu etal. (2008). In 250-mL PTFE centrifuge bottles, thedried sludge samples were extracted with 50 mL of abuffer solution prepared by mixing 2 g of Na2ED-TA·2H2O with 25 mL of pH 3 buffer (27.2 g ofKH2PO4 and 1.36 mL of H3PO4 in 1 L water) and25 mL of acetonitrile. The bottles were agitated on anorbital shaker for 2 h and subsequently centrifuged for10 min (4,000 rpm). The supernatant was collected andmixed with 150 mL of water to decrease theacetonitrile content prior to SPE. Oasis HLB cartridges

(1 g) were conditioned with 5 mL of methanolfollowed by 5 mL of pH 3 buffer. Samples were thenpassed through the cartridge at a flow rate of 10–15 mL·min−1. Cartridges were subsequently flushedwith 10 mL water, dried for 10 min under vacuum, andeluted with 10 mL of 6% NH3 in methanol. The eluatewas then evaporated to about 500 μL under nitrogenand brought to 2 mL with acetonitrile.

2.5 Instrumental Analysis

HPLC High-performance liquid chromatography(HPLC) with UV detection was used for the determina-tion of target PPCPs. For estrogens (E1, E2, E3, EE2,and EA), caffeine, triclosan, and ciprofloxacin, anAlltech Prevail C18 column (25 cm×4.6 mm i.d.,5 μm) was used for separation. Mobile phase character-istics varied depending on the analyte of interest. Forestrogens, the mobile phase was acetonitrile:water (flowrate=0.8 mL·min−1), which was set at 60:40 (v/v)initially. The mobile phase was changed to 65:35 at1.0 min, and to 100% acetonitrile at 11.5 min. Then,the mobile phase was maintained at 100% acetonitrileuntil 15.0 min, changed to 60:40 at 15.5 min, andmaintained at 60:40 until 21.0 min. For caffeineseparation, the mobile phase was 50:50 acetonitrile:water (isocratic; flow rate=0.8 mL·min−1). Triclosanwas chromatographed using a mobile phase containingacetonitrile:water (isocratic; 80:20v/v; flow rate=0.8 mL·min−1). For ciprofloxacin determination, themobile phase was a pH 3.5 solution (isocratic; flow

Table 3 Calculated detection limits for target PPCPs obtained from HPLC/UV analysis of spiked samples

Compound Method detection limita

Wastewater (μg/L) Groundwater (ng/L) Sludge (ng/g dry weight) Soil (ng/g dry weight)

E1 01.12 8.08 6.42 0.96

E2 0.12 3.19 6.42 0.96

E3 0.12 17.73 6.42 0.40

EE2 0.12 4.78 6.42 0.96

EA 0.12 17.34 6.42 0.96

Caffeine 0.10 9.95 6.39 0.30

Triclosan 0.12 14.09 5.87 1.04

Ibuprofen 0.70 34.15 25.56 3.72

Ciprofloxacin 0.05 13.53 4.12 0.37

a Determined using US EPA 2000 guideline where MDL=SD× t (99%; n−1) and assuming 1 L of water and 1 g of sludge/soil wereextracted

262 Water Air Soil Pollut (2011) 216:257–273

rate=1.0 mL·min−1) prepared from 800 mL of water,190 mL of acetonitrile, and 10 mL of triethylamine.This solution was adjusted to pH 3.5 using phosphoricacid. For ibuprofen separation, an Agilent ZorbaxEclipse XDB-C8 column (15 cm×4.6 mm i.d., 5 μm)was used with a mobile phase of acetonitrile:phospho-ric acid–acetonitrile (isocratic; 80:20v/v; flow rate=1.0 mL·min−1). The phosphoric acid–acetonitrile solu-tion was prepared by mixing 0.5 mL of phosphoricacid and 340 mL of acetonitrile adjusted to 1,000 mLvolume with water. Detection wavelengths were200 nm for estrogens and triclosan, 254 nm forcaffeine, 214 nm for ibuprofen, and 279 nm forciprofloxacin.

2.6 GC/MS Confirmations

We conducted GC/MS confirmations on 39% of allwastewater samples, 63% of all sludge samples, 36%of all groundwater samples, and 18% of all soilsamples. Prior to GC/MS determination, sampleswere derivatized using N-methyl-N-(trimethylsilyl)-trifluoroacetamide (MSTFA) following methods ofThomas et al. (2002) and Thomas and Foster (2004).Derivatized samples were analyzed using GC/MS inthe selected ion monitoring (SIM) mode using therespective parent and one to two daughter ions foreach compound.

3 Results and Discussion

3.1 PPCPs in Wastewater

The results obtained from the analysis of wastewatersamples collected from the WRP are presented inTable 4. All target PPCPs were detected in thetreatment process at a range of not detected (ND)-183 μg/L; as expected, observed concentrations fluc-tuated among quarters. The fluctuation of PPCPconcentrations may be attributed to the use of PPCPsthat likely varied daily, let alone quarterly. In general,concentrations of PPCPs in effluent at both stationswere less than those in influent (bar rack or aerationbasin) in the same quarter except for EE2 in the firstand the third quarters and ciprofloxacin in the secondquarter. Lower concentrations of PPCPs in the effluentcompared with those in the influent suggest that these

compounds can be removed during the treatmentprocess. Among PPCPs studied, ibuprofen had thehighest concentrations in the influent (range=ND-183 μg/L), while E3 had the highest concentrationsin the effluent (both chlorine contact chamber oreffluent stations) with a range of ND-87 μg/L. Insome quarters, E1, E2, E3, EE2, and ciprofloxacinappeared in bar rack samples at concentrations lowerthan in aeration basin, chlorine contact chamber, oreffluent station samples. Occasionally higher concen-tration of these compounds in the effluent than those inthe influent suggests that these compounds may not beeasily degraded or the inactive conjugates of estrogensmay be deconjugated during the wastewater treatmentprocess resulting in the release of the active parentcompound to produce higher effluent concentrations(Kirk et al. 2002; Andersen et al. 2003; D’Ascenzo etal. 2003). Another possible reason of the higherconcentrations of PPCPs in the effluent than theinfluent may simply be the daily variations of thesecompounds since influent samples were collectedbetween 2 and 4 PM and may not represent the peakload. Although effluent samples were collected duringthe same period as influent samples (bar rack), effluentsamples, as well as other samples downstream of theinfluent, are more representative of conditions from theprevious 24 h (the residence time of the system).

There was a difference in PPCP concentrationsbetween Plants 3 and 4, at the aeration basins andeffluent stations of each plant. In addition, for somequarters, concentrations of PPCPs in samples from theeffluent station were higher than those from the chlorinecontact chamber of the same plant. The difference inPPCP concentrations between aeration basins andeffluent stations of each plant and PPCP concentrationsfrom the effluent station which were higher than thosefrom chlorine contact chamber may be attributed to thefact that these locations likely have different microbialpopulations. This in turn affects plant performance,water quality and PPCP removal. E2, triclosan, caffeine,and ibuprofen were detected in effluent at lowerconcentrations than in the influent during the entirestudy period, suggesting that these compounds can beremoved efficiently from wastewater by the wastewatertreatment processes at the WRP.

To date, there is no wastewater treatment processspecifically responsible for the removal of PPCPs.However, several studies have indicated that estro-gens, triclosan, caffeine, ibuprofen, and ciprofloxacin

Water Air Soil Pollut (2011) 216:257–273 263

can be reduced or eliminated in biological wastewatertreatment systems using the activated sludge (aerationbasin) process, where sorption to particles andbiotransformation are potential mechanisms of PPCPremoval (Sedlak and Pinkston 2001; Giger et al.2003; Andersen et al. 2005; Bester 2005; Thomas andFoster 2005; Thompson et al. 2005; Nakada et al.

2006; Kim et al. 2008). It is also likely that some ofPPCPs in this study were removed from wastewatervia chlorination. Snyder et al. (2008) suggested that amajority of PPCPs such as estrogens and triclosan inwastewater can be effectively oxidized using chlori-nation. Our study is supportive of this as concentrationsof PPCPs in wastewater samples from the bar rack were

Table 4 Concentrations (μg/L) of target PPCPs in wastewater from the WRP

Compound Date Bar rack Aeration basin Chlorine contact chamber Effluent

Plant 3 Plant 4 Station I Station II

E1 12/16/08 3.25 3.18 3.67 –a 1.43 1.82

3/11/09 1.47 0.74 1.63 0.42 0.49 0.59

6/3/09 ND 0.22 2.82 1.54 0.33 0.48

9/9/09 1.29 ND ND ND ND ND

E2 12/16/08 4.62 1.30 1.38 –a ND 1.37

3/11/09 2.29 ND 1.12 0.36 0.50 ND

6/3/09 0.90 1.66 1.58 0.80 0.26 0.75

9/9/09 1.58 0.73 0.50 ND ND 0.67

E3 12/16/08 0.68 7.45 13.97 –a 0.25 7.60

3/11/09 110.7 126.5 29.19 86.71 83.43 59.23

6/3/09 ND 37.51 7.29 7.66 13.08 2.76

9/9/09 25.71 ND ND ND ND ND

EE2 12/16/08 ND ND ND –a 0.08 0.39

3/11/09 7.89 ND ND 0.16 ND ND

6/3/09 ND ND 0.12 0.81 0.26 ND

9/9/09 ND ND ND ND ND ND

Triclosan 12/16/08 5.10 0.12 ND –a 0.26 0.13

3/11/09 8.12 ND 0.77 ND ND ND

6/3/09 1.90 0.44 ND 0.14 0.15 0.17

9/9/09 0.70 ND ND 1.41 0.18 0.35

Caffeine 12/16/08 23.60 ND ND –a ND ND

3/11/09 41.04 0.35 ND 0.12 0.17 0.34

6/3/09 45.48 5.35 ND ND ND ND

9/9/09 53.43 ND ND ND ND ND

Ibuprofen 12/16/08 ND ND ND –a ND ND

3/11/09 182.9 3.47 ND 3.82 4.06 ND

6/3/09 ND 2.10 0.71 ND ND ND

9/9/09 41.63 ND ND ND ND ND

Ciprofloxacin 12/16/08 ND ND ND –a ND ND

3/11/09 ND 0.12 0.06 0.41 0.27 ND

6/3/09 0.09 0.27 ND ND ND ND

9/9/09 ND 0.84 ND ND ND 0.30

ND Not detecteda No sample

264 Water Air Soil Pollut (2011) 216:257–273

generally higher than those from the aeration basins,chlorine contact chamber, and effluent stations.

3.2 PPCPs in Sludge

Results obtained from the analysis of sludge samplescollected from the WRP are presented in Table 5.Target PPCPs in the solid phase of sludge samples

ranged from ND-18.6 μg/g. In the sludge liquidphase, target PPCPs ranged from ND-50 μg/L exceptfor EE2, which was not detected in the sludge liquidphase during the entire study period. Concentrationsof estrogens in the sludge solid phase are likelyunderestimated due to the low recovery (poor extrac-tion) of these compounds (<51±3.2%). In sludgesolid phase, E1, E2, E3, EE2, triclosan, caffeine, and

Table 5 Concentrations of target PPCPs in sludge from the WRP

Compound Date Feed sludge Anaerobic digested sludge

Solid phase (μg/g) Liquid phase (μg/L) Solid phase (μg/g) Liquid phase (μg/L)

E1 12/16/08 3.27 39.9 1.60 28.2

3/11/09 2.40 0.42 2.52 2.60

6/3/09 0.70 3.22 ND 50.1

9/9/09 6.59 14.1 1.16 11.2

E2 12/16/08 0.70 1.54 0.04 0.48

3/11/09 2.23 2.84 1.50 3.47

6/3/09 0.13 ND 0.22 ND

9/9/09 ND 18.3 0.12 9.44

E3 12/16/08 ND 3.55 ND 3.49

3/11/09 ND 46.5 ND 16.3

6/3/09 0.01 2.76 0.01 0.61

9/9/09 ND ND 0.01 ND

EE2 12/16/08 0.34 ND 0.19 ND

3/11/09 ND ND ND ND

6/3/09 ND ND ND ND

9/9/09 ND ND ND ND

Triclosan 12/16/08 7.79 6.98 3.35 12.1

3/11/09 3.52 2.84 3.39 3.73

6/3/09 4.70 1.00 5.67 3.47

9/9/09 18.6 11.6 2.48 4.22

Caffeine 12/16/08 ND 0.53 ND ND

3/11/09 0.02 ND 0.01 ND

6/3/09 ND ND ND ND

9/9/09 ND 24.8 ND ND

Ibuprofen 12/16/08 ND ND 3.61 ND

3/11/09 ND ND 4.10 ND

6/3/09 ND 3.91 ND 3.10

9/9/09 ND 27.6 1.57 ND

Ciprofloxacin 12/16/08 ND ND ND 0.46

3/11/09 ND ND ND ND

6/3/09 4.37×10−3 ND 4.29×10−3 0.06

9/9/09 ND ND ND ND

ND Not detected

Water Air Soil Pollut (2011) 216:257–273 265

ciprofloxacin in samples from the anaerobic digesterwere generally lower than in feed sludge, except forE1 in the second quarter, E2 in the second and thethird quarters, E3 in the fourth quarter, and triclosanin the third quarter. Lower PPCP concentrations in thesolid phase of digested sludge may be due todesorption from the solid phase into the liquid phase;the sludge retention time in the anaerobic digester was30 days which was a long period for desorption.When present at detectable levels, ibuprofen concen-trations in sludge solid phase from the anaerobicdigester were higher than those from the feed sludgechamber in every quarter. Higher concentrations ofibuprofen in solid phase of digested sludge than thoseof feed sludge may occur because dissolved ibuprofenin the sludge liquid phase could sorb onto the solidphase or the ibuprofen concentration might beaffected by the previous sludge load since thesesamples represented conditions over the last 24 h.

In the sludge liquid phase, EE2 was the onlycompound that was not detected from both the feedsludge chamber and anaerobic digester during the entirestudy period; caffeine was not detected in any samplesfrom the anaerobic digester. For other compounds insludge liquid phase, the trend of PPCP concentrations infeed sludge compared to anaerobic digested sludge wasdifficult to predict. In some quarters, PPCPs appeared atlower concentrations in sludge liquid phase from feedsludge than in the anaerobic digester, but this trend didnot occur in other quarters. E1, E2, E3, triclosan,ibuprofen, and ciprofloxacin were detected in the sludgeliquid phase from either feed sludge or the anaerobicdigester, except for some quarters in which they werenot detectable in any samples from either samplingpoint. The unpredictable concentrations in the sludgeliquid phase along the treatment train (from feed sludgechamber to anaerobic digester), together with thefluctuations in the amount of sorbed PPCPs in sludgesolid phase of the same samples suggests that slowsorption kinetics and no equilibrium occurred betweenthe sorbed and dissolved PPCPs in sludge duringtreatment at the WRP.

Sorption to sludge is believed to be an importantmechanism for the removal of hydrophobic organicchemicals from wastewater (Harrison et al. 2006).Therefore, it is important to know the association ofPPCPs with sludge. Among the estrogens tested, E3had the lowest log Kow (Table 1) with a high watersolubility; therefore, it is less likely to sorb onto sludge

particles. This is supported by our results where E3concentrations in the effluent from theWWTP (Table 4)and the sludge liquid phase (Table 5) were generallyhigher than concentrations of other estrogens. EE2 hasa relatively high log Kow with the lowest watersolubility among test estrogens and should have a hightendency to sorb onto sludge; however, it was rarelydetected in both solid and liquid phases of sludge inthis study. A rare detection of EE2 in sludge despite itsrelatively high log Kow may be the result of irreversiblesorption to sludge and/or very low concentrations ofEE2 in the wastewater treatment plant. E1 and E2 weredetected in both phases of sludge more often than otherestrogens, suggesting that these compounds readilysorb and desorb to sludge, probably due to a high logKow and a high water solubility for E1, and a moderatelog Kow and a high water solubility for E2 compared toother estrogens. The lower concentrations of estrogensin the anaerobic digester may be the result ofbiodegradation during the sludge treatment process.Studies have reported that estrogens can be biode-graded during anaerobic sludge digestion (Holbrook etal. 2002; Kreuzinger et al. 2004a).

Among all test PPCPs, triclosan had the highest logKow (4.76). Although triclosan was detected at moderateconcentrations in wastewater samples compared to othertarget chemicals, it was the only compound detected inall sludge samples (both solid and liquid phases),suggesting that triclosan readily sorbs onto the sludgesolid phase, but may not be easily biodegraded in theanaerobic digester. This is supported by other studiesreporting that little or no biodegradation of triclosanoccurred under anaerobic sludge digestion (McAvoy etal. 2002; Chenxi et al. 2008).

Compared to other PPCPs, caffeine had a veryhigh water solubility (2.16×104 mg/L) with thelowest log Kow (−0.07); therefore, it was not likelyto adsorb to sludge. Our results indicated that caffeinewas rarely detected in the sludge solid phase. Inaddition, other researchers have reported that caffeinemay be readily biodegraded during wastewater treat-ment (Ternes et al. 2001; Buerge et al. 2003; Thomasand Foster 2005). The biodegradation of caffeineresults in lower or non-detectable concentrations inboth the solid phase and liquid phase of sludge.Furthermore, with a high log Kow (3.97) and a lowwater solubility (21 mg/L), ibuprofen should readilyadsorb to the sludge solid phase. However, desorptionmay also occur during the sludge treatment process

266 Water Air Soil Pollut (2011) 216:257–273

resulting in the detection of ibuprofen in sludge liquidphase whereas no ibuprofen was detected in sludgesolid phase. For ciprofloxacin, sorption to the sludgesolid phase may not easily occur because of its lowlipophilicity relative to the other test PPCPs. More-over, ciprofloxacin in sludge may not be easilybiodegraded as reported by other investigators(Chenxi et al. 2008).

3.3 PPCPs in Soil

The results obtained from the analysis of soil samplescollected from the LAS are presented in Table 6.Target PPCPs were detected in the soil from inside

pivot irrigation (ND-112 ng/g) and in soil fromoutside pivot irrigation (ND-319 ng/g). Except forcaffeine and ciprofloxacin, target PPCPs weredetected both inside and outside pivot area indicatingthat PPCPs are being transported via runoff. Amongtest PPCPs, caffeine was the only compound notdetected in any soil sample, whereas ibuprofen wasdetected at the highest concentrations every quarter.Ciprofloxacin was detected only in the third quarter ata depth of 0–6 in. inside pivot area (CL-11) at aconcentration of 0.68 ng/g. Concentrations of cipro-floxacin might be underestimated due to its lowrecovery from soil (28±7%). Surprisingly, the observedconcentrations of PPCPs in soil fluctuated among

Table 6 Concentrations (ng/g) of target PPCPs in soil from the LAS

Compound Sampling Date CL-11a CL-29b CL-43a CL-48b

0–6" 12–18" 24–30" 0–6" 12–18" 24–30" 0–6" 12–18" 24–30" 0–6" 12–18" 24–30"

E1 3/9/09 –c –c –c 7.55 10.04 8.52 7.82 34.52 20.61 5.30 8.68 6.73

6/30/09 9.62 3.45 ND 9.53 7.33 4.96 3.28 9.59 20.83 4.60 7.63 6.71

9/16/09 ND ND ND ND 44.06 135.9 ND ND ND 2.03 ND ND

E2 3/9/09 –c –c –c ND ND 1.20 0.19 ND 3.33 0.17 0.58 0.65

6/30/09 2.09 2.41 ND ND ND ND 1.71 ND ND 1.86 ND ND

9/16/09 2.84 ND ND ND ND ND ND ND ND ND ND ND

E3 3/9/09 –c –c –c 4.07 ND ND 7.73 ND ND ND ND ND

6/30/09 ND 1.01 ND 2.22 1.18 ND 1.63 3.14 1.20 2.98 1.00 1.08

9/16/09 ND ND 0.53 0.46 3.60 5.98 2.10 0.85 0.76 0.98 ND ND

EE2 3/9/09 –c –c –c ND ND ND ND ND ND ND ND ND

6/30/09 1.21 1.26 ND ND ND ND ND ND ND ND ND ND

9/16/09 ND 2.62 ND 2.03 2.70 ND ND ND ND ND ND ND

Triclosan 3/9/09 –c –c –c 5.24 3.20 ND ND ND ND ND ND ND

6/30/09 ND 2.91 ND 8.16 1.24 1.09 1.94 1.33 7.81 ND ND ND

9/16/09 ND ND ND ND ND ND 19.15 ND ND ND ND ND

Caffeine 3/9/09 –c –c –c ND ND ND ND ND ND ND ND ND

6/30/09 ND ND ND ND ND ND ND ND ND ND ND ND

9/16/09 ND ND ND ND ND ND ND ND ND ND ND ND

Ibuprofen 3/9/09 –c –c –c 36.11 36.60 108.3 24.16 26.68 44.68 18.20 33.82 69.93

6/30/09 26.78 ND 94.07 ND ND ND ND 17.51 ND ND 9.63 33.66

9/16/09 95.19 75.93 111.5 314.8 318.5 280.3 76.99 102.5 100.6 37.24 134.4 215.5

Ciprofloxacin 3/9/09 –c –c –c ND ND ND ND ND ND ND ND ND

6/30/09 ND ND ND ND ND ND ND ND ND ND ND ND

9/16/09 0.68 ND ND ND ND ND ND ND ND ND ND ND

ND Not detecteda Inside pivot irrigationb Outside pivot irrigationc No sample

Water Air Soil Pollut (2011) 216:257–273 267

quarters, and were unpredictable at various soil depths.EE2 was the only compound that was not detected inany samples at the 24–30-in. depth, although it wasdetected in the upper soil depths at the same samplinglocation. This indicates that EE2 is not easily leachedand vertical transport of EE2 is low, even in the sandysoils characteristic of the LAS.

Concentration fluctuations of target PPCPs in soilamong quarters were likely due to varying concen-trations of PPCPs in the WWTP effluent. PPCPsapplied to the land with irrigation are subject tovolatilization from soil and vegetation surfaces,chemical and biological degradation, sorption, andplant uptake (Cordy et al. 2004; Cardoza et al. 2005;Boxall 2008; Xu et al. 2009). In the soil environment,sorption is believed to be an important processgoverning the mobility of organic compoundsincluding PPCPs (Drillia et al. 2005; Boxall 2008),whereas volatilization and degradation are processesgoverning the elimination of these compounds.Photodegradation may be a pathway for the removalof target PPCPs on surface soil exposed to sunlightsince these compounds can be degraded by wave-lengths in the environmental UV spectrum (Phillipset al. 1990; Lin and Reinhard 2005; Aranami andReadman 2007; Belden et al. 2007; Mazellier et al.2008; Nakada et al. 2008; Matamoros et al. 2009).

In this study, E1, E2, E3, triclosan, and ibuprofenwere detected in soil samples at a depth of 24–30 in.,indicating that these compounds were mobile andpersistent enough to undergo leaching in the soil. Anytrend in target PPCP concentrations with soil depth wasdifficult to discern and is likely due to the variousbiodegradation rates of PPCPs with soil depth; degra-dation of PPCPs can be affected by environmentalconditions such as temperature, pH, moisture content,organic carbon, presence of specific microorganisms,and presence/absence of oxygen (Colucci et al. 2001;Boxall 2008; Monteiro and Boxall 2009). For example,Ying and Kookana (2005) found that the degradationof E2 and EE2 was different in non-sterile aerobic soil(half-lives=3 and 4.5 days, respectively), but neithercompound was degraded in sterile soil over 70 days. Inanaerobic soil, E2 was degraded slowly (half-life=24 days) while EE2 had no significant degradationover the 70 days. These results suggest that thedegradation of PPCPs is influenced by the presenceof microorganisms and oxygen which could bevariable with soil depth. Volatilization was not a likely

pathway for target PPCP elimination since all targetPPCPs had very low vapor pressures (≤1.86×10−4 mmHg) except for caffeine. Caffeine had thehighest vapor pressure (15 mmHg) among targetPPCPs and the biodegradation of caffeine in soiloccurs rapidly both in aerobic and anaerobic conditions(Topp et al. 2006). These are logical reasons for thelack of caffeine detections in soil in this study.

Among estrogens investigated, E1 was detected insoil at the LAS more often than other estrogens andwas detected at the highest concentrations although itwas present at the same level as E2 and at lowerlevels than E3 in the effluent from the WRP. Severalstudies have reported that E2 is biotransformed to E1rapidly under both aerobic and anaerobic conditionsin soils (Colucci et al. 2001; Jacobsen et al. 2005;Ying and Kookana 2005; Xuan et al. 2008). The highconcentrations of E1 at all soil depths in the studymay be the result of biotransformation of E2 into E1.E3 was detected in soil at concentrations lower thanE1 although it was present at higher concentrationsthan E1 in the effluent from the WRP. The lowerconcentrations of E3 in soil compared to those of E1might be due to higher soil mobility of E3 (lower logKow and Kd), resulting in less E3 adsorbed to soil.

3.4 PPCPs in Groundwater

The results obtained from the analysis of groundwatersamples collected from the LAS are presented in Table 7.Concentrations of PPCPs in groundwater were in therange of ND-1,745 ng/L. E1, E2, E3, EE2, triclosan,and caffeine were detected in groundwater samplesfrom wells inside and outside the pivot area. Ibuprofenwas the only compound that was not detected in anygroundwater sample. Ciprofloxacin was detected(45 ng/L) only in the first quarter (March) at amonitoring well inside pivot irrigation (CL-43).Compared to other compounds, E3 was detected ingroundwater at the highest concentration except forthe last quarter (September) in which E3 was notdetectable, suggesting that E3 has a higher mobilityin soil than other compounds since it was mostfrequently detected in groundwater but not mostfrequently detected in soil. In the third quarter (latesummer), most PPCPs studied were non-detectableexcept for EE2 and caffeine which were detected atrelatively low concentrations, 11 ng/L and 16 ng/L,respectively. This could be result of rainfall and high

268 Water Air Soil Pollut (2011) 216:257–273

degradation rates of target PPCPs in soil andgroundwater that may occur during this season.Although caffeine was not detected in any soilsamples, it was detected in some effluent andgroundwater samples, suggesting that caffeine didnot readily adsorb to soil or have a higher degrada-tion rate than other target compounds in the subsur-face environment.

Target PPCPs in groundwater likely originate fromthe LAS soil, a portion of which is continually receivingwastewater effluent. Runoff and subsurface transport areimportant processes for movement of PPCPs and otherorganic compounds from soil to groundwater (Manselland Drewes 2004; Overcash et al. 2005; Sangsupan etal. 2006). PPCPs in the soil at the site applied with theeffluent may transport to groundwater through theseprocesses. The extent of PPCPs in groundwater can beaffected by sorption and biodegradation of thesecompounds (Kreuzinger et al. 2004b; Mansell et al.2004; Snyder et al. 2004; Osenbrück et al. 2007).

Among PPCPs studied, E3 was detected at thehighest concentrations in groundwater, likely due to itslow Kd in this soil (8.6 mL/g). Ibuprofen was notdetected in any groundwater samples although it wasdetected at the highest concentrations in soil. However,ibuprofen has a high log Kow (3.97), which is higherthan other target PPCPs except for triclosan. Caffeinewas detected in groundwater samples despite not beingdetected in any soil samples, likely the result ofenhanced mobility of caffeine in this soil (very lowlog Kow, −0.07, and a high water solubility).

3.5 GC/MS Confirmations

The derivatization method followed by GC/MSanalysis was successful in helping qualitativelyconfirm the presence of target PPCPs in samplescollected from the WRP and the LAS. A minimum of18% of wastewater, sludge, groundwater, and soilsamples were analyzed. Overall, the GC/MS data for

Compound Sampling Date CL-11a CL-29b CL-43a CL-48b

E1 3/9/09 c 79 75 62

6/30/09 ND ND ND ND

9/16/09 ND ND ND ND

E2 3/9/09 c 12 147 34

6/30/09 39 ND ND 78

9/16/09 ND ND ND ND

E3 3/9/09 c 1745 874 538

6/30/09 686 322 1661 676

9/16/09 ND ND ND ND

EE2 3/9/09 c ND 230 102

6/30/09 15 ND ND ND

9/16/09 ND ND ND 11

Triclosan 3/9/09 c 17 16 12

6/30/09 ND 45 53 ND

9/16/09 ND ND ND ND

Caffeine 3/9/09 c 119 166 164

6/30/09 ND ND ND ND

9/16/09 16 ND ND ND

Ibuprofen 3/9/09 c ND ND ND

6/30/09 ND ND ND ND

9/16/09 ND ND ND ND

Ciprofloxacin 3/9/09 c ND 45 ND

6/30/09 ND ND ND ND

9/16/09 ND ND ND ND

Table 7 Concentrations (ng/L) of target PPCPs ingroundwater from the LAS

ND Not detecteda Under pivot irrigationb Outside pivot irrigationc No sample

Water Air Soil Pollut (2011) 216:257–273 269

the samples were consistent with HPLC/UV data;however, in some instances the GC/MS method wasable to detect target PPCPs in samples that wereclassified as non-detect using HPLC/UV. For certaintarget compounds, it appeared that the GC/MSmethod in the SIM mode was slightly more sensitivethan HPLC/UV.

4 Conclusions

Target PPCPs were detected in wastewater, sludge,soil, and groundwater at the study sites. Some PPCPscan be removed from wastewater during the treatmentprocess, particularly the aeration basin (activatedsludge); however, E3, EE2, ibuprofen, and ciproflox-acin were occasionally detected in the effluent athigher concentrations than in the influent. All PPCPsstudied were detected both in the sludge solid phaseand the sludge liquid phase except for EE2 which wasnot detected in the sludge liquid phase. Expected tobe high in summer and low in winter, concentrationsof target PPCPs in wastewater, sludge, and soil ateach depth varied in an unpredictable manner. Onlygroundwater tended to have less PPCP occurrenceduring summer. At the LAS, PPCPs moved bothvertically, since they were detected along soil depth,and horizontally via runoff since they were detectedin soil and groundwater both inside and outside pivotirrigation. Caffeine was detected in effluent andgroundwater, but was not detected in soil, suggestingthat caffeine may not readily adsorb to soil or thedegradation rate of caffeine was high in soil from thesite. E3 was the most frequently detected testcompound in groundwater, but not the most frequentlydetected compound in soil, indicating that E3 may havea higher mobility in soil than other test compounds.Ibuprofen was detected in wastewater and soil, but notdetected in groundwater, suggesting that ibuprofen mayreadily sorb to the soil and have a low degradation ratein the soil.

Overall, findings of this study indicate that PPCPsin the effluent from a wastewater treatment plant caneventually move to groundwater via land applicationof the effluent. However, PPCPs detected in ground-water at the study site were at low concentrationswhich are not likely to represent a concern andindicate that the land application process is reasonablyeffective at PPCP removal given that treated waste-

water has been applied to the site for more than70 years. Our findings may be important forevaluating the potential long-term effects of PPCPsfrom contamination of soil and eventually ground-water if that water is to be used for drinking waterpurposes. Data presented here can provide usefulinformation for the upgrade of a wastewater treat-ment system or could aid in management decisionson the application of treated wastewater to land andpotentially reducing exposure to PPCPs.

Acknowledgments This study was partially funded by theTexas Water Resources Institute (TWRI) and the US EPA.Special thanks to individuals for assisting in sample collectionand access to the WRP and the LAS.

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