Surface-Modified Multi-lumen Tubular Membranes for SAGD-Produced Water Treatment

Abstract

The extraction of bitumen from oil sands using steam-assisted gravity drainage (SAGD) produces a considerable amount of oily process water that must be recycled. Ceramic membranes are well suited for this task, but membrane fouling remains a significant barrier to their widespread application. Bituminous clays in produced water are heavily charged and interact with the charged surfaces of ceramic membranes in a way that reduces membrane performance. To address this problem, the surfaces of commercially available multi-lumen tubular ceramic membranes were chemically modified using several charge-neutral polyethylene oxide (PEO)-based organosilanes. Membranes with a pore size of 10 nm and selective layers of either γ-Al 2 O 3 or TiO 2 were modified based on protocols previously used on small-scale ceramic membrane disks and challenged with SAGD-produced water. Results indicate that the modification leads to an improvement in membrane performance. Modification of γ-Al 2 O 3 membranes by a 30% solution of straight-chain PEO-silane increased permeate flux by factors as high as 2.9. Modification of TiO 2 membranes also improved permeate flux. Flux recovery factors upon backflushing increased from 1.3 to 1.6. Furthermore, flux values for γ-Al 2 O 3 membranes ranged between 50 and 150 Lmh and increased over time, while flux values for TiO 2 membranes ranged between 220 and 350 Lmh and declined slightly over time. This indicates that γ-Al 2 O 3 is a stronger adsorbent for bituminous foulants than TiO 2 , with foulants being adsorbed quickly and subsequently released during filtration and backflushing. Finally, the decline in performance when switching to a SAGD feed, with a higher pH, total organic carbon and alkalinity, was significantly less severe for modified TiO 2 membranes compared to unmodified counterparts. Based on these results, surface modification of tubular ceramic membranes with PEO-based silanes was successful in improving the rejection of bituminous foulants from the membrane surface.

Textured ceramic membranes for desilting and deoiling of produced water in the Permian Basin

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Treatment Technologies for Organics and Silica Removal in Steam-Assisted Gravity Drainage Produced Water: A Comprehensive Review

“…It is worthy to note that most studies mentioned above were set up at about 50 °C due to the low thermal stability of the thin-film polymeric membrane. , In order to apply membrane filtration in a SAGD produced water treatment, where the actual operating temperature is between 80 and 90 °C, membranes that can withstand high temperature are required. Swenson et al used thin membranes that have a high natural zeolite content to treat synthetic SAGD produced water at high temperature (85 °C) .…”

State-of-the-Art Ceramic Membranes for Oily Wastewater Treatment: Modification and Application

“…Therefore, the grafting layer has long-term chemical stability. The precursors for grafting are mostly polymers such as fluoroalkylsilanes (FAS) [66], poly(vinylpyrrolidone) (PVP) [67], polyethylene oxide (PEO) [68] and poly(vinylacetate) (PVAc) [69]. To initialize the grafting, membrane surfaces may be pretreated by chemicals, UV-irradiation, plasma, or enzymes [70].…”

“…In this case, the attraction of these foulants to the ceramic membrane surface should be prevented. Atallah et al [68] modified the γ-Al 2 O 3 and TiO 2 ceramic membranes with polyethylene oxide (PEO) functional organosilanes for produced water treatment. The membrane became more hydrophilic but charge-neutral.…”