In Alberta, Canada, the oil-sands industry plays an important role in the local economy, however the industry is the largest water consumer and has a significant impact on the environment. Only 20% of the available bitumen can be extracted by surface mining, while the rest can be produced by in-situ methods. For in-situ methods, steam is typically injected into the reservoir to reduce the bitumen viscosity, allowing the bitumen to be pumped to the surface along with water. In order to avoid hardness and silica in the produced water from fouling the steam generators, water treatment processes are needed. The treatment of this produced water is challenging as it contains dissolved silica, a high level of hardness and complex organics. Our research has shown that electrocoagulation (EC) is a viable technology to remove a large variety of contaminants. This technology applies the concept of electrochemistry by using sacrificial metal electrodes in an electrochemical cell to produce metal hydroxide coagulants that can efficiently remove contaminants by either adsorption or charge neutralization [1].

In this study, a continuous flow-through cell was designed to remove the contaminants from produced water and synthetic produced water following the same inorganic compositions as the produced water. Mild steel and aluminum were evaluated as electrode materials for the EC treatment process. The results show that EC was very effective for removal of dissolved silica in both real and synthetic produced water. More than 90% of the silica was removed using a charge loading of less than 1000 coulomb of charge per liter of water treated, which corresponds to less than ten minutes of treatment under the experimental conditions used. The effect of design and operating parameters including: water flowrate, current density, dissolved oxygen concentration, and electrode spacing will be reported.

References:

[1] D. Moussa, M. El-Nass, M. Nasser, and M. Al-Marri. "A comprehensive review of electrocoagulation for water treatment: Potentials and challenges." Journal of Environmental Management, vol. 186, pp. 24-41, 2017.