Removal of trace organics by anaerobic membrane bioreactors Victor M. Monsalvo a, *, James A. McDonald b , Stuart J. Khan b , Pierre Le-Clech c a Chemical Engineering Section, University Autonoma de Madrid, C/Francisco Tomas y Valiente 7, Madrid 28049, Spain b Water Research Centre, The University of New South Wales, Sydney, NSW 2052, Australia c UNESCO Centre for Membrane Science and Technology, School of Chemical Engineering, The University of New South Wales, Sydney, NSW 2052, Australia article info Article history: Received 22 July 2013 Received in revised form 16 November 2013 Accepted 18 November 2013 Available online 27 November 2013 Keywords: Anaerobic Biodegradability Fouling Membrane bioreactor (MBR) Sorption Trace organics abstract The biological removal of 38 trace organics (pharmaceuticals, endocrine disruptors, per- sonal care products and pesticides) was studied in an anaerobic membrane bioreactor (AnMBR). This work presents complete information on the different removal mechanisms involved in the removal of trace organics in this process. In particular, it is focused on advanced characterization of the relative amount of TO accumulated within the fouling layers formed on the membranes. The results show that only 9 out of 38 compounds were removed by more than 90% while 23 compounds were removed by less than 50%. These compounds are therefore removed in an AnMBR biologically and partially adsorbed and retained by flocs and the deposition developed on the membranes, respectively. A total amount of 288 mg of trace organics was retained per m 2 of membrane, which were distributed along the different fouling layers. Among the trace organics analyzed, 17a- ethynylestradiol, estrone, octylphenol and bisphenol A were the most retained by the fouling layers. Among the fouling layers deposited on the membranes, the non-readily detachable layer has been identified as the main barrier for trace organics. ª 2013 Elsevier Ltd. All rights reserved. 1. Introduction There is an increasing concern about the presence of trace or- ganics (TO), such as pharmaceutically active compounds (PhACs), personal care products (PCPs), endocrine disrupting compounds (EDCs) and pesticides in water bodies worldwide. It is reasonable to surmise that the occurrence of TO in the envi- ronment is not a newly emerging phenomenon but, it has become more widely evident thanks to the recent improve- ments of the chemical analysis methodologies and the lower detection limits for a wide spectrum of trace xenobiotics in environmental samples. The analysis of the TO cycle in nature reveals the important role that wastewater treatment plants (WWTP) play on the control of their occurrence in the envi- ronment (Daughton and Ternes, 1999). Conventional WWTP and septic systems have not been specifically designed to remove xenobiotic organics present at trace levels, hardly * Corresponding author. Tel.: þ34 914975615; fax: þ34 914972981. E-mail address: victor.monsalvo@uam.es (V.M. Monsalvo). Available online at www.sciencedirect.com ScienceDirect journal homepage: www.elsevier.com/locate/watres water research 49 (2014) 103 e112 0043-1354/$ e see front matter ª 2013 Elsevier Ltd. All rights reserved. http://dx.doi.org/10.1016/j.watres.2013.11.026