Sometimes nature does it best

oil sands wetland

At Imperial’s Kearl project, there’s a corner of the oil sands mine property where grasses and bulrushes grow thick and tall in the summer. At a distance, this area might look like just any marshland in this northern Alberta region. 

But up close there are signs this is no ordinary wetland. Its outline is rectangular. It’s surrounded by an engineered berm, and a raised bank of earth. If this property is different, and it is—that’s because it’s a pilot project by Imperial to test the use of a constructed wetland to clean oil sands process-affected water (water that has come into contact with the oil sands).

For the past five years, scientists have been studying the capacity of this one-hectare wetland to treat water that’s pumped into it. One of those experts is Alex Cancelli, a PhD candidate at Simon Fraser University’s School of Resource and Environmental Management.

“What we’ve been trying to do is harness the natural ability of this ecosystem to treat oil sands process-affected water from the mine,” says Cancelli, who has spent the past five summers conducting field studies. According to Cancelli, constructed treatment wetlands have been used successfully for years in other industries to treat agricultural runoff, industrial wastewater and municipal water systems.

“They’re used because they are so cost-effective and easy to operate and because they’re natural. They host active microorganisms (unseen microbial life) that can extract unwanted chemicals to essentially clean the water,” Cancelli explains.

The wetland at Kearl was initially developed seven years ago, making it one of the first features of its kind in the oil sands. Since 2015, the company has been pumping different types of oil sands process-affected water through the wetland to assess the results in a controlled and monitored fashion. 

The water is directed through a series of rectangular depressions, or cells, excavated at different depths and carefully lined to prevent any process water from seeping into the groundwater. Specialized sampling devices dotted throughout the site measure chemical concentrations in the water.

For some time now, Cancelli and staff at Kearl have been taking instrument readings and gathering water samples to analyze the quality and toxicity of water entering and leaving the wetland. They’ve been supported in this research by scientists at Imperial’s Calgary Research Centre and ExxonMobil’s Biomedical Sciences Laboratory in New Jersey. 

For his part, Cancelli has focused on the wetland’s ability to remove problematic chemicals (complex hydrocarbons like naphthenic acids) which are widely present in oil sands process-affected water. While the water that has been transferred to the treatment wetland to date is not particularly high in these and other constituents of potential concern, the results, he says, are very promising. 

“We’ve been able to show that this wetland system can efficiently remove a large portion of these chemicals from oil sands process-affected water,” Cancelli says. “We want to better understand how and why, and optimize that capability using water with higher concentrations of these chemicals of concern.”

To take the project to the next step, the company has begun flying drones over the area to track changes in vegetation from the air. Cancelli and researchers at Imperial have also developed, and are currently testing, a computer model to help better understand how these chemicals behave in wetland systems. The model will provide a tool that can be used to further assess the wetland’s efficiency and optimize the construction and operation of future treatment wetland projects. 

“There’s a lot of opportunity to engineer constructed wetlands and incorporate other related technologies to enhance this natural treatment system,” Cancelli says.

Interested in other innovation stories like these? Check out these other COSIA blogs.
•    We can build wetlands, now what? 
•    Bugs help vegetation grow on tailings 
•    Water management 101: Using water wisely 

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