16 th International Conference on Environmental Science and Technology Rhodes, Greece, 4 to 7 September 2019 CEST2019_00659 Hybrid zero liquid discharge (ZLD) membrane/chemical process for the treatment of oil sands produced water Mohammadtabar F. 1 , Khorshidi B. 1 , Sadrzadeh M. 1,* 1 Department of Mechanical Engineering, 10-367 Donadeo Innovation Center for Engineering, Advanced Water Research Lab (AWRL), University of Alberta, Edmonton, Alberta T6G 1H9, Canada *corresponding author: Mohtada Sadrzadeh , e-mail: sadrzade@ualberta.ca Abstract In this study, the applicability of a hybrid chemical/membrane process for the treatment of the boiler blow-down (BBD) water from steam assisted gravity drainage (SAGD) operation was explored. For the chemical pre-treatment prior to the membrane filtration, another waste stream of SAGD, i.e., ion exchanger regeneration wastewater (IERW), was used as a coagulant to reduce the concentration of organic matter and silica. The proposed method involved the direct use of the NF process for the purification of BBD water, followed by an integrated IERW conditioning and nanofiltration (NF) to purify the concentrated retentate. This process could operate with a zero-liquid discharge (ZLD) configuration and it was found to be an efficient method in terms of water recovery and water product quality. Keywords: Wastewater treatment; Membrane; Nanofiltration; Process integration 1. Introduction Water is an essential material for the oil sands industry, and many studies are focused on the improvement of the water treatment process in the SAGD operation. Different chemical methods, such as coagulation and ion exchange resins, are currently used in the SAGD plants to remove contaminants, particularly silica, calcium, and magnesium as these ions are mainly responsible for causing fouling and scaling of boiler tubes (Hayatbakhsh et al., 2016; Maiti et al., 2012; Pillai et al., 2017; Sadrzadeh et al., 2015; Shamaei et al., 2018). Several studies have indicated the high efficiency of hybrid treatment processes regarding fouling mitigation and water recovery (Li et al., 2011; Yang and Kim, 2009). Therefore, in this work, a hybrid membrane-based separation process was proposed for the treatment of BBD water. This method involved direct filtration of the BBD water with an NF process with 50% water recovery ratio (NF1) followed by the treatment of concentrated retentate by the IERW as a coagulant. IERW conditioning was conducted as a novel chemical pre-treatment for another post-treatment by an NF as the final polishing stage (NF2 in Figure 1). The IERW conditioning indicated a high removal of organic matter and silica. The effectiveness of the process was investigated regarding permeate flux, contaminant removal and fouling characteristics of the NF process. Figure 1. The proposed hybrid treatment process illustrating the ZLD configuration 2. Materials and Methods Table 1 shows the properties of the main streams in the proposed hybrid process. Membrane filtration tests were conducted using the DOW FILMTEC NF90 membrane and a cross-flow filtration setup. Table 1: Properties of IERW and BBD water. Paramet er Unit BBD water IERW water IERW inlet IERW outlet TDS ppm 6525 66625 8500 16750 pH --- 11.6 6.2 10.9 11.6 Turbidity NTU 0.86 0.25 0.9 1.2 TOC ppm 230 6.7 443 108 Silica ppm 78 5.2 111 3.2 Mg 2+ ppm 0.24 2200 0.16 0.07 Ca 2+ ppm 2.97 9450 2.78 3.82 Na + ppm 1806 22165 3975 8069