Treatment of oil sands process-affected water with ceramic ultrafiltration membrane: Effects of operating conditions on membrane performance Alla Alpatova a , Eun-Sik Kim a,b , Shimiao Dong a , Nian Sun a , Pamela Chelme-Ayala a , Mohamed Gamal El-Din a,⇑ a Department of Civil and Environmental Engineering, University of Alberta, Edmonton, Alberta T6G 2W2, Canada b Department of Environmental System Engineering, Chonnam National University, 50 Daehak-ro, Yeosu, Jeonnam, 550-749, South Korea article info Article history: Received 4 June 2013 Received in revised form 4 November 2013 Accepted 5 November 2013 Available online 12 November 2013 Keywords: Ultrafiltration Ceramic membrane Oil sands Coagulation Fouling mechanism abstract This study investigated the performance of 1 kDa ceramic ultrafiltration membrane for the removal of inorganic and organic compounds from oil sands process-affected water (OSPW) generated after thermal operations of heavy oil recovery in Alberta, Canada. The OSPW was pretreated with alum coagulant, and the effect of operating conditions on subsequent membrane filtration was studied. While permeate flux increased with increasing trans-membrane pressure (TMP) from 1.4 bar to 3.5 bar, greater permeate flux decline was observed at TMP of 3.5 bar due to increased accumulation of foulants at the membrane sur- face. The membrane filtration performed at cross-flow velocity (CFV) of 0.2 L/min was characterized by the lowest initial and steady-state permeate fluxes and by the highest normalized flux decline compared to higher CFVs. This effect was attributed to lower turbulence at the membrane surface which might have promoted the buildup of contaminants. According to the resistance-in-series model, no irreversible mem- brane fouling was observed when OSPW was pretreated with coagulation–flocculation–sedimentation. The pore blocking and cake layer formation dominated at the beginning of filtration, whereas cake layer formation was the primary fouling mechanism at later stages. The final membrane permeates met the requirements for the high pressure-driven membrane processes (i.e., nanofiltration and reverse osmosis) with respect to turbidity and silt density index (SDI 15 ) values. Up to 38.6 ± 2.7% (depending on TMP and CFV values) of chemical oxygen demand (COD) was removed, and the removal percentages of the acid extractable fraction (AEF) and naphthenic acids (NAs) were less because of the small sizes of NAs and other organic compounds contributing to the AEF as compared to the membrane pore sizes. Ó 2013 Elsevier B.V. All rights reserved. 1. Introduction During thermal operations of heavy oil recovery in Northern Al- berta, Canada, the caustic soda is used to extract bitumen from the oil sands, and four cubic meters of the oil sands process-affected water (OSPW) are produced per one cubic meter of oil sands [1]. The water demand for this process is met by OSPW recycling and by the fresh water uptake from the Athabasca River [2]. As a result, the quality of OSPW which is a complex mixture of solids, dis- solved organic and inorganic species as well as metals [3], deterio- rates due to concentrating of organic and inorganic constituents during OSPW recycle. Under no-release policy, operating compa- nies store OSPW in tailing ponds in order to avoid its release into the receiving environment [2,4]. To achieve the sustainability of the oil sands operations, OSPW needs to be treated to decrease its toxicity and to facilitate its reclamation for safe release into the receiving environment and/or for treated-OSPW recycle for re- use to minimize the volume of the fresh water uptake. Various chemical, physical, physicochemical and biological treatments have been evaluated in order to develop a performance-efficient and cost-effective strategy for OSPW remediation [5–10]. The use of membrane filtration for water treatment has in- creased worldwide because of the advances in treatment efficiency and reduction in operational costs [11,12]. Low pressure-driven membrane processes such as microfiltration and ultrafiltration (UF) are being considered as attractive alternatives for municipal and industrial water treatment [13–15]. The use of ceramic mem- branes due to their excellent chemical resistance to inorganic acids, bases, oxidants, the tolerance to high temperatures and long- 1383-5866/$ - see front matter Ó 2013 Elsevier B.V. All rights reserved. http://dx.doi.org/10.1016/j.seppur.2013.11.005 ⇑ Corresponding author. Address: NSERC Senior Industrial Research Chair in Oil Sands Tailings Water Treatment, Helmholtz – Alberta Initiative Lead (Theme 5), 3-093 Markin/CNRL Natural Resources Engineering Facility, Department of Civil and Environmental Engineering, University of Alberta, Edmonton, Alberta T6G 2W2, Canada. Tel.: +1 780 492 5124; fax: +1 780 492 0249. E-mail address: mgamalel-din@ualberta.ca (M. Gamal El-Din). Separation and Purification Technology 122 (2014) 170–182 Contents lists available at ScienceDirect Separation and Purification Technology journal homepage: www.elsevier.com/locate/seppur