Elsevier

Environmental Pollution

Volume 164, May 2012, Pages 267-273
Environmental Pollution

Occurrence and persistence of organic emerging contaminants and priority pollutants in five sewage treatment plants of Spain: Two years pilot survey monitoring

https://doi.org/10.1016/j.envpol.2012.01.038Get rights and content

Abstract

This work summarized all results obtained during almost two-years of a monitoring programme carried out in five municipal sewage treatment plants (STPs) located in the north, centre and south-east of Spain. The study evaluated the occurrence and persistence of a group of 100 organic compounds belonging to several chemical groups (pharmaceuticals, personal care products, pesticides and metabolites). The average removal efficiencies of the STPs studied varied from 20% (erythromycin) to 99% (acetaminophen). In analysed samples, we identified a large number of compounds at mean range concentrations between 7–59,495 ng/L and 5–32,720 ng/L for influent and effluent samples, respectively. This study also identified 20 of the mostly detected and persistent compounds in wastewater effluent, of which hydrochlorothiazide, atenolol, gemfibrozil, galaxolide and three metabolites (fenofibric acid, 4-AAA and 4-FAA), presented the highest average contribution percentages, in relation to the total load of contaminants for the different STPs effluent studied.

Graphical abstract

Highlights

► The results summarize two-years of a monitoring programme. ► 100 organic compounds (priority substances and emerging contaminants) were analysed. ► The removal efficiency of 5 STPs of Spain was evaluated. ► The presence of target compounds in treated wastewater was also checked. ► The most frequently drugs detected were: antibiotics<anti-inflammatories<β-blockers.

Introduction

From 1970, thanks to a range of EU environmental directives, the quality of surface water in Europe has improved significantly. Now, in the Member States of the European Union, the chemical quality of surface waters is controlled under the Water Framework Directive (WFD) 2000/60/EC (Directive 2000/60/EC). Within this framework, the key strategy adopted, in the area of chemical pollution, was the Decision 2455/2001/EC which established a list of 33 substances or groups of substances of priority concern due to their persistence, toxicity, bioaccumulation and widespread use and detection in rivers, lakes, transitional and coastal waters. Also, more recently, Directive 2008/105/EC has been a new step in the progress of regulation, establishing for the first time, quality standards (EQS) for priority substances and other pollutants of concern, to ensure adequate protection of the aquatic environment and human health. Among the objectives, other chemicals, of emerging interest, are being included in a review process for identification as possible “priority substances” or “hazardous substances” due to their potential risk. Actually, 13 new substances are under a review process (European Parliament Legislative Resolution, 2008), 7 are pharmaceuticals and 6 are personal care products.

In the last years, many organic contaminants from anthropogenic origin, so-called “emerging” contaminants, are being subject of high concern among the scientific community due to their frequent detection in aquatic environment. Highlights pharmaceuticals or personal care products (PPCPs) which are highly consumed by modern society; these substances are continually introduced in the aquatic environment, through sewage treatment plants (STPs) or directly via release from the skin during swimming or bathing (Daughton and Ternes, 1999). From the consumption standpoint of these products, a report published by the British Government compared the consumption of 14 groups of drugs in 14 countries, revelling that the Spanish people are Europeans that consume more drugs, only surpassed by the Americans, and followed by France, Denmark and Australia (Richards, 2010).

To protect the environment from the potential chemical pollution of urban wastewater discharges and emissions from the industry, a considerable progress has been made following the implementation of the Directive 91/271 (UWWD) (Directive of the European Communities, 1991). In Spain, progress in addressing waste water-related challenges resulting from this regulation, has ensured notable improvements, in quantity and quality of water. However, in many cases, the effectiveness of these WWTPs for removing chemicals is limited, by secondary treatment processes, such as biological filters and activated sludge (Gómez et al., 2007; Zuccato et al., 2005). Therefore, a large number of organic contaminants escape to treatments becoming ubiquitous contaminants in the environment.

The most common procedures used to carry out the determination of organic compounds in aquatic environmental matrices applied sample preconcentration steps, such as solid-phase extraction (SPE) (Martínez Bueno et al., 2010), solid-phase microextraction (SPME) (Rodriguez et al., 2006), stir bar sorptive extraction (SBSE) (Roldil and Moeder, 2008) or liquid–liquid extraction (LLE) (Gómez et al., 2009), followed by separation and determination using liquid (LC) or gas chromatography (GC), couple with mass spectrometry (LC–MS or GC–MS). Tandem mass offers higher performance than single-quadrupole instruments, in terms of sensitivity and selectivity. So, triple-quadrupole, ion trap or hibrid triple quadrupole-ion trap systems are one of the most frequently chosen techniques for analysed organic compounds in complex matrices. LC–MS/MS has been the technique most referenced for the analysis of polar and semi-polar organic compounds in environmental samples until currently (Gros et al., 2009; Martínez Bueno et al., 2007). For determination of non-polar analytes, relatively volatile and thermally stabile substances, GC–MS has usually been the analytical methodology applied in these types of matrices (Robles-Molina et al., 2010). In this work, in order to achieve the identification and quantification of a high number of organic compounds from several chemical groups, LC–MS/MS and GC–MS were chosen as multi-residue analytical techniques to carry out the screening of wastewater samples.

The main objective of the present article, developed as a part of an ambitious research programme (TRAGUA) financed by the Spanish Government, has been to obtain information during almost two-years of monitoring sampling, in order to evaluate removal efficiency of five STPs of Spain and the presence of chemicals in WWTP effluents that are discharges to the environment. This study has been focused on a group of 100 organic compounds that includes 7 “priority substances”, one chemical under review process for its identification as “priority and/or hazardous substances”, and 92 “emerging” contaminants. Monitoring information is presented analysing the results in terms of average total load of contaminants detected in each STPs selected and mean contribution of each analyte against the total load of contaminants in the sewage effluents. Moreover, a seasonal and monthly variation from the discharged effluent of WWTPs were also worthy of investigation in this study.

Section snippets

Experimental section

A detailed discussion of the sample treatment techniques and analytical methods used in this study has been included as supplementary information (see Supplementary Data).

Results and discussion

A comprehensive overview of the validation results obtained has been included as supplementary data (see Table S1).

Information regarding frequency of detection for each compound, concentration ranges and mean concentrations detected in effluents after applied a secondary treatment in the 5 STPs selected in this study, can be seen in Table S2. In terms of frequency of detection, most of chemicals were detected at least once time over the campaign developed from the 100 contaminants included in

Conclusions

Levels detected in wastewaters of emerging contaminants were in the ranging from a few ng/L to few hundred ng/L, with the exception of some compounds, such as atenolol, hydrochlorothiazode, gemfibrozil, galaxolide, caffeine, acetaminophen, diclofenac, ofloxacin, ibuprofen, codeine, naproxen, paraxanthine, 4-AAA, 4-FAA or fenofibric acid, which showed concentration up to μg/L, both influents and sewage effluents. Antibiotics and analgesics/anti-inflammatories were the most frequently drugs we

Acknowledgements

The authors wish to acknowledge the Spanish Ministry of Education and Science (Programa Consolider Ingenio 2010 CE-CSD2006-00044 and Proyect CTM2007-65544/TECNO) for their economic support.

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