Treatment of an in situ oil sands produced water by polymeric membranes

AbstractCross-flow ultrafiltration (UF), nanofiltration (NF), and reverse osmosis (RO) were applied for the first time on a produced water obtained from a thermal in situ bitumen recovery process called steam-assisted gravity drainage (SAGD), with the intent to remove salt, silica, and dissolved organic matter (DOM) so that the produced water could be re-used as high-quality boiler feedwater. It was found that more hydrophilic and more negatively charged membranes were less susceptible to fouling. The UF membrane tested rejected a maximum of 30% of the salt and silica and 50% of the DOM. Nanofiltration with loose membranes removed more than 70% of the salt and DOM. The tight NF membranes tested removed more than 86% of the salt, silica, and DOM, and consumed less energy than RO, which showed almost the same rejection. An instantaneous increase in water flux resulting from a step change in feedwater pH demonstrated the critical role of pH in flux recovery and in fouling mitigation. Analysis of the fouled m...