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Sep 10, 2011 - investigate the occurrence and fate of selected emerging contaminants in sewage treatment plant (STP) of Athens (Greece) during two ...
Proceedings of the 12th International Conference on Environmental Science and Technology Rhodes, Greece, 8 - 10 September 2011

OCCURRENCE AND FATE OF EMERGING CONTAMINANTS IN SEWAGE TREATMENT PLANT OF ATHENS N. S. THOMAIDIS1, A. S. STASINAKIS2, D. MAMAIS3, V.G. SAMARAS2, A. ASIMAKOPOULOS1, O.S. ARVANITI1, E. IATROU2, A. AJIBOLA1, E.I. VENTOURI1 and T.D. LEKKAS2 1

Laboratory of Analytical Chemistry, Department of Chemistry, National and Kapodistrian University of Athens, Zografou, Athens 157 71, Greece 2 Department of Environment, Water and Air Quality Laboratory, University of the Aegean, University Hill, Mytilene 81100, Greece 3 Department of Water Resources, Faculty of Civil Engineering, National Technical University of Athens, 5 Iroon Polytechniou Str., Athens 15773, Greece E-mail: [email protected] ABSTRACT

Several synthetic organic compounds that have been classified as emerging contaminants are commonly detected in municipal wastewater and they are of significant research and practical interest, due to their chemical and toxicological properties that affect safe disposal and reuse of treated wastewater. The aim of this study was to investigate the occurrence and fate of selected emerging contaminants in sewage treatment plant (STP) of Athens (Greece) during two seasonal sampling campaigns. For this purpose, wastewater (influents and secondary effluents) and sludge samples were collected in seven consecutive days in each sampling campaign (December 2010 and April 2011). Samples were analyzed for the determination of four different classes of emerging contaminants, namely phenolic endocrine disrupting compounds (EDCs), pharmaceuticals (NSAIDs), perfluorinated compounds (PFCs), benzothiazoles (BThs) and benzotriazoles (BTzs). On the total, 37 different compounds were detected (5 EDCs, 4 NSAIDs, 18 PFCs, 4 BThs and 4 BTzs) in 28 wastewater and 14 sewage sludge samples. For the qualitative and quantitative analyses, gas chromatography-mass spectrometry was used for EDCs and NSAIDs, while liquid chromatography - tandem mass spectrometry was used for the rest of the compounds. The seasonal and daily variations of target compounds’ concentrations were investigated and the results were compared to those reported in the literature for other STPs worldwide. Daily mass flows normalized to inhabitants were calculated and distribution of target compounds between dissolved and particulate phase was determined for wastewater samples. A mass balance was also performed to investigate the fate of EDCs during wastewater treatment and to estimate the role of degradation and sorption on their removal. To investigate possible effects due to the reuse of treated wastewater for agricultural purposes and disposal of treated wastewater to the aquatic environment, toxicity experiments were performed using seed germination, root elongation techniques and Vibrio fischeri bioassay. Finally, the role of advanced treatment processes on the removal of target compounds from biologically treated wastewater was studied in lab-scale experiments. For this reason, experiments were performed using coagulation-flocculation, filtration using membranes and chlorination under different experimental conditions. KEYWORDS: Endocrine Disrupting Compounds, Pharmaceuticals, Perfluorinated Compounds, Benzothiazoles, Benzotriazoles, Removal, Toxicity, Risk assessment.

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1.

INTRODUCTION

The term “emerging pollutants” primarily refers to those substances for which no regulations currently require monitoring or public reporting of their presence in our aquatic environment (Wells et al., 2010). These substances are widely released in the environment and, nowadays, there is an increased interest and research on their occurrence and fate. It is worth mentioning that emerging pollutants are detected at higher concentrations and at much higher rates in comparison to the priority pollutants in every monitoring campaign (Teijon et al., 2010). Nevertheless, due to their large number (ranging in an order of thousands), a very small percentage of these compounds are toxicologically evaluated. Published data concerning occurrence and potential toxicological effects is limited. The contamination source of the aquatic system is mainly the effluents from the sewage treatment plants (STPs). Additionally, the extent in which the current water and wastewater treatment infrastructures can effectively remove these compounds is also, in a great extent, an unknown parameter (Oulton et al., 2010). The inefficient removal poses a serious environmental problem. There is also lack of knowledge for the fate of several groups of emerging pollutants during wastewater treatment. Moreover, several questions have been posed such as the relation between chemical structure and biodegradability and the relation between hydrophobicity and accumulation to sludge. In parallel, few data are available for the fate of emerging pollutants in the aquatic environment after treated wastewater disposal to the surface water. Additionally, there is a lack of data concerning the metabolites of organic micropollutants which are formed during wastewater treatment and disposal, while there are no data either for the toxicity of metabolites, or for the metabolic pathways which lead to the formation of these metabolites. It should be mentioned that the aforementioned lack of data is sometimes due to the absence of adequate analytical methods for the detection of these pollutants in difficult matrices such as wastewater and sludge. These difficulties in environmental analysis are much more significant in cases that the identification of metabolites is desired (Ballesteros-Gómez and Rubio, 2011). Among the most detected emerging compounds in wastewater are the perfluorinated compounds (PFCs), benzotriazoles (BTris), benzothiazoles (BTs), phenolic endocrine disrupters (EDCs) and pharmaceuticals and personal care products (PPCPs). So far there are limited data for their fate during wastewater treatment and treated wastewater disposal to the aquatic environment. Perfluorinated compounds have emerged as global environmental contaminants due to their persistency, bioaccumulation and toxicity (Loganathan et al., 2007). Benzotriazoles and benzothiazoles are high-volume produced industrial chemicals, which were recently detected in 95% of samples originating from European rivers (Loos et al., 2009). Municipal wastewater seems to be the most significant route of their transfer to the environment (Weiss and Reemtsma, 2005), with removals differentiated according to the target compound (Reemtsma et al., 2010). Phenolic endocrine disrupters (EDCs), the most significant among them being nonylphenols (NPEs), bisphenol A (BPA) and triclosan (TCS), present significant scientific interest and usually have both industrial and domestic sources and regularly detected in wastewater and sludge (Stasinakis et al., 2008). Finally, pharmaceuticals are detected regularly and at high concentrations in wastewaters and surface waters and they have raised concerns due to their pharmacological activity (Oulton et al., 2010). The tendency for these compounds to persist or be only partially degraded during treatment or to bypass treatment altogether via sewage overflows contribute to their load in receiving waters, many of which serve as recreational and drinking water sources (Oulton et al., 2010; Zhang and Li, 2011). Among them, non-steroidal anti-inflammatory drugs (NSAIDs) are constantly detected at high concentrations (Nikolaou et al., 2007; Oulton et al., 2010). The aim of this study was to investigate the occurrence and fate of selected emerging contaminants in sewage treatment plant (STP) of Athens (Greece) during two seasonal sampling campaigns. Samples were analyzed for the determination of four different

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classes of emerging contaminants, namely 5 EDCs, 4 NSAIDs, 18 PFCs, 4 BTs and 4 BTris. A mass balance was also performed to investigate the fate of these compounds during wastewater treatment and to estimate the role of degradation and sorption on their removal. To investigate possible effects due to the reuse of treated wastewater for agricultural purposes and disposal of treated wastewater to the aquatic environment, toxicity experiments were performed using seed germination, root elongation techniques and Vibrio fischeri bioassay. Finally, the role of advanced treatment processes on the removal of target compounds from biologically treated wastewater was studied in labscale experiments. Due to space restrictions, a limited data from the first sampling campaigns is presented. 2. MATERIALS AND METHODS 2.1. Studied compounds The studied compounds were nonylphenol (NP), nonylphenol monoethoxylate (NP1EO), nonylphenol diethoxylate (NP2EO), bisphenol A (BPA) and triclosan (TCS) from EDCs, and ibuprofen (IBF), naproxen (NPX), ketoprofen (KTF) and diclofenac (DCF) from NSAIDs. Eighteen PFCs, namely perfluoropentanoic acid (PFPeA), perfluorohexanoic acid (PFHxA), perfluoroheptanoic acid (PFHpA), perfluorooctanoic acid (PFOA), perfluorononanoic acid (PFNA), perfluorodecanoic acid (PFDA), perfluoroundecanoic acid (PFUdA), perfluorododecanoic acid (PFDoA), perfluorotridecanoic acid (PFTrDA), perfluorotetradecanoic acid (PFTeDA), potassium perfluorobutanesulfonate (L-PFBS), perfluorohexanesulfonate (L-PFHxS), perfluoroheptanesulfonate (L-PFHpS), perfluorooctanesulfonate (L-PFOS), perfluorodecanesulfonate (L-PFDS), perfluorooctane sulfonamide (PFOSA), N-methylperfluorooctane sulfonamide (N-MeFOSA), Nethylperfluorooctane sulfonamide (N-EtFOSA) were monitored. Moreover, five BTris, namely 1H-benzotriazole (BTri), its methylated compounds, 4-methylbenzotriazole (4TTri), 5-methylbenzotriazole (5-TTri), 5,6-dimethylbenzotriazole (5,6-DMBTri) and 1hydroxy-benzotriazole (1-OH-BTri) and four major BTs, namely benzothiazole (BT), 2hydroxy-benzothiazole (2-OH-BT), 2-methylthiobenzothiazole (2-MeThio-BT) and 2amino-benzothiazole (2-amino-BT) were determined. 2.2. Sampling campaigns Wastewater (influents and secondary effluents) and sludge samples were collected in seven consecutive days in each sampling campaign (December 2010 and April 2011) from the STP of Athens (Psyttaleia WWTP). All wastewater samples were 24-h composite flow-proportional samples. The STP receives wastewater originating from domestic and industrial sources. 2.3. Analytical methods Wastewater samples were filtered through glass microfiber filter with nominal pore size of 0.45 μm (Millipore), acidified at pH 2.5 and stored in the dark at 4 ˚C until solid phase extraction (SPE). For the determination of analytes in the particulate matter (suspended solids), filters were oven dried until constant weight and stored at -20 °C until their analysis. Sewage sludge samples were oven dried at 60 °C, dry sludge was ground and homogenized with a mortar and pestle and stored at -20 °C until analysis. EDCs and NSAIDs were determined according to Samaras et al. (2011). PFCs in wastewaters were extracted with SPE (Oasis HLB 200 mg, 6 mL). The cartridge was eluted with 4 mL methanol and the elution was evaporated to dryness. The residue was reconstituted in 500 μL mobile phase (CH3OH/HCOONH4, 50:50, v/v), filtered and 10 μL were analyzed by LC-(–)ESI-MS/MS. Extraction of PFCs from solid samples (suspended particulate matter and sewage sludge) was performed by 7.5 mL of 1% acetic acid and A-1883

1.5 mL methanol (×3). The total supernatant is diluted with ultrapure water up to 50 mL and the same SPE was performed and finally analyzed by LC-MS/MS. BTs and BTris in wastewaters were extracted with SPE (Stata-X 200 mg, 6 mL). The cartridge was eluted with 4 mL methanol and the elution was evaporated to dryness. The residue was reconstituted in 500 μL mobile phase (ACN/formic acid 0.1%, 50:50, v/v), filtered and 10 μL were analyzed by LC-(+)ESI-MS/MS. Extraction of BTs and BTris from solid samples was performed by 10 mL of a water and methanol mixture (50:50). The total supernatant is diluted with ultrapure water up to 50 mL, the same SPE was performed, and finally analyzed by LC-MS/MS. 3. RESULTS AND DISCUSSION The results of the first sampling campaign are presented in Tables 1 and 2. According to the analyses, the mean concentrations of all the target compounds were ranged between LODa

Mean ± SD

Mean ± Sd

Mean ± SD

Mean ± SD

Removal (%)

Compound

LOD -1 (ng L )

NP

3.8

7

8825 ± 3086

7

3896 ± 1180

50 ± 22

NP1EO

1.9

7

1167 ± 512

7

405 ± 176

61 ± 19

NP2EO

6.6

7

1948 ± 618

7

347 ± 253

81 ± 13

TCS

3.6

7

662 ± 258

7

78 ± 62

87 ± 11

BPA

14

7

1420 ± 731

7

253 ± 278

84 ± 11

IBF

0.90

7

727 ± 697

0