Oil-Sands Produced Water Treatment by Electrocoagulation

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Several technologies are used in Canada whereby steam is injected into bitumen (oil-sands) reservoirs to reducebitumen viscosity and enable oil production. The oil is thus produced at high temperatures, mixed with aboutthree times the volume of water. Once the oil is separated, the water is treated, fed to the steam generators andrecycled to the wells. The produced water contains a complex mixture of inorganic and organic contaminantsthat can foul the boilers and contaminants are typically removed by a combination of physical and chemicaltreatment processes. Around 80% of the water is recycled as steam, the remaining 20% collected as aconcentrated 'blowdown', around of half of which can be recycled and the remaining part is disposed of. Thiswater treatment process has high capital and operating costs, and critically effects the environmentalperformance including the amount of disposal water and the consumption of make up water. In the currentclimate of low oil prices and increasing environmental regulation, new water treatment technology is needed toreduce costs and enhance the environmental performance of oil sands production. Electrocoagulation iseffective for removal of silica and other contaminants, and there is significant potential for the applicationelectrocoagulation as a new solution for treatment of produced water or blowdown. However, the complexchemistry in produced water systems can lead to operational and performance problems, and research is neededto understand removal mechanisms and electrode fouling processes to tailor the technology for theseapplications. Our industry partner is planning to apply electrocoagulation for the treatment of produced water.The project will enable them to ensure that electrocoagulation is used as efficiently and effectively as possible.This will reduce operating and capital costs and lead to a significant reduction in water use and disposal. Theproject will involve investigation of the interaction of contaminants with the electrocoagulation process, as afunction of the operating conditions. State of the art instruments will be used to investigate the contaminantremoval mechanisms, to provide reliable performance data and recommend suitable operating conditions.