On the applicability of a hybrid bioreactor operated with polymeric tubing for the biological treatment of saline wastewater M. Concetta Tomei a, ⁎, Domenica Mosca Angelucci a , Valentina Stazi a , Andrew J. Daugulis b a Water Research Institute, C.N.R., Via Salaria km 29.300, CP 10, 00015 Monterotondo Stazione (Rome), Italy b Department of Chemical Engineering, Queen's University, Kingston K7L 3N6, Ontario, Canada HIGHLIGHTS • A novel tubing bioreactor was applied for treating saline wastewater. • Different polymer tubing have been tested: Hytrel G3548 gave the best per- formance. • Salt separation and biodegradation of organics was achieved in a single unit. • Organic removal efficiency of 99% was reached in the tubing stream. GRAPHICAL ABSTRACT abstract article info Article history: Received 23 March 2017 Received in revised form 3 May 2017 Accepted 4 May 2017 Available online 12 May 2017 Editor: D. Barcelo Effective biological treatment of high salt content wastewater requires consideration of both salt and organic tox- icity. This study treated a synthetic saline wastewater containing NaCl (100 g L -1 ) and 2,4-dimethylphenol (1.2 g L -1 ) with a hybrid system consisting of a biological reactor containing spiral-coiled polymeric tubing through which the mixed feed was pumped. The tubing wall was permeable to the organic contaminant, but not to the salt, which allowed transfer of the organic into the cell-containing bioreactor contents for degradation, while not exposing the cells to high salt concentrations. Different grades of DuPont Hytrel polymer were exam- ined on the basis of organic affinity predictions and experimental partition and mass transfer tests. Hytrel G3548 tubing showed the highest permeability for 2,4-dimethylphenol while exerting an effective salt barrier, and was used to verify the feasibility of the proposed system. Very high organic removal (99% after just 5 h of treatment) and effective biodegradation of the organic fraction of the wastewater (N 90% at the end of the test) were ob- served. Complete salt separation from the microbial culture was also achieved. © 2017 Elsevier B.V. All rights reserved. Keywords: Saline wastewater Continuous two-phase partitioning bioreactor Polymer tubing Hybrid bioreactors Selective mass transfer Biological treatment 1. Introduction The treatment of saline wastewater arising from a broad cross- section of industries such as agro-food operations, and textile process- ing poses significant challenges (Lefebvre and Moletta, 2006). This is be- cause saline wastewater contains not only high salt (inorganic) concentrations but is also contaminated with a variety of organic com- pounds. Such a combination of inorganic/organic pollutants makes the design of effective treatment facilities particularly difficult as overall treatment must be able to obtain high removal efficiency of the organic components while also achieving efficient removal or recovery of the salt. This challenge is generally met by combining a number of separate treatment operations (e.g. chemical/physical for salt removal and bio- logical for organics removal) into an integrated, multi-step treatment process, as no single treatment process for both types of contaminants is commercially available. Science of the Total Environment 599–600 (2017) 1056–1063 ⁎ Corresponding author. E-mail address: tomei@irsa.cnr.it (M.C. Tomei). http://dx.doi.org/10.1016/j.scitotenv.2017.05.042 0048-9697/© 2017 Elsevier B.V. All rights reserved. Contents lists available at ScienceDirect Science of the Total Environment journal homepage: www.elsevier.com/locate/scitotenv