Journal of Hazardous Materials 263P (2013) 146–157 Contents lists available at ScienceDirect Journal of Hazardous Materials j o ur nal homep age: www.elsevier.com/locate/jhazmat Occurrence and removal efficiency of pesticides in sewage treatment plants of four Mediterranean River Basins Julian Campo ∗ , Ana Masiá, Cristina Blasco, Yolanda Picó Food and Environmental Safety Research Group (SAMA-UV), Faculty of Pharmacy, University of Valencia, Av. Vicent Andrés Estellés s/n, 46100 Burjassot, Valencia, Spain h i g h l i g h t s • Thirty-four currently used pesticides were quantified in influents and effluents. • Up to 24 pesticides were present in dehydrated sludge samples. • Pesticide removal efficiencies in STPs confirm that pesticides are only partially eliminated. • STPs could be a focal point of pesticide contamination to the Rivers. a r t i c l e i n f o Article history: Received 20 March 2013 Received in revised form 31 July 2013 Accepted 26 September 2013 Available online 3 October 2013 Keywords: Wastewater Sludge LC–MS/MS Pesticides Removal efficiency a b s t r a c t Removal of contaminants in the sewage treatment plants (STPs) can be incomplete causing their release to the environment. In this paper, the results of an extensive survey on more than 40 pesticides carried out in 2010 and 2011 in 16 STPs of Ebro, Guadalquivir, Jucar and Llobregat Rivers (Spain) are presented. In 2010, of 43 analytes screened, 29 were detected in influent and 28 in effluent samples, meanwhile in 2011, of 50 analytes, 33 and 34 were detected, respectively. Pesticides were in the range of 0.33 ng L -1 (terbume- ton, 2011)–2526.05 ng L -1 (diuron, 2010) for influent and 0.25 ng L -1 (terbumeton, 2011)–2821.12 ng L -1 (carbendazim, 2011) for effluent. Regarding the sludge samples, 11 pesticides were detected in 2010 and 24 in 2011 at concentrations up to 25667.34 ng g -1 dry weight (dw). Removal efficiencies showed that, in 2010, the elimination ranged from -810% (chlorfenvinphos) to 93% (dimethoate), and in 2011, from -4575% (diazinon) to 97% (chlorfenvinphos). All these data confirm that most of the pesticides are only partially eliminated during the secondary and even tertiary treatments, commonly used in STPs, suggesting that they can be a focal point of contamination to the rivers. © 2013 Elsevier B.V. All rights reserved. 1. Introduction The re-use of sewage treatment plant (STP) effluents is cur- rently one of the most employed strategies in several countries to deal with the water shortage problem. This water can be recycled in agricultural irrigation, for municipal and industrial purposes, to maintain the ecological flow, to recharge aquifers or it can be directly discharged into rivers or the sea [1–3]. Removal of con- taminants by STPs is, in some cases, not complete and, accordingly, the occurrence of contaminants and residues in this water is of concern, because of their likely entry into the environment [4]. Currently, the European Water Framework Directive (WFD) [5] has established bases to regulate the water resources with the objective of preserving, protecting and improving their quality and sustainable use, through a list of 33 priority substances (that ∗ Corresponding author. Tel.: +34 963543092; fax: +34 963544954. E-mail address: julian.campo@uv.es (J. Campo). is now enlarging) to be controlled, the third part of which are pesticides [6]. Pesticides – widely applied to protect plants from diseases, weeds and insects damage – are also bio-accumulative and due to their vertebrate and non-vertebrate toxicity, they can affect non- target organisms [7], especially in the aquatic ecosystems [4,8]. As widely recognized and because of the extensive crop treat- ments, surface water pollution by pesticides mostly results from water runoff, agricultural storm-water discharges and return flows from irrigated agriculture. As the runoff moves, it picks up and carries away pesticides, finally depositing them into lakes, rivers, wetlands, coastal waters and ground waters. Polar and highly sol- uble pesticides have been frequently detected mainly in surface and wastewaters at ng L -1 concentration range [1,9–16]. However, much of this uncontrolled runoff finishes also in the STPs. There are few peer-reviewed articles that analyse concentrations of pes- ticides in Spanish STPs [1,17] and these have been reported mainly in those located along the Llobregat River [4,8,10], making clear a lack of research in other rivers. Additionally, due to the lack of 0304-3894/$ – see front matter © 2013 Elsevier B.V. All rights reserved. http://dx.doi.org/10.1016/j.jhazmat.2013.09.061