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Water recycling in a nutshell

November 2015 – We’ve gone nutty on water recycling – literally. We’re using crushed walnut shells to treat and filter some of the water we use to get oil out of the oil sands. It turns out that walnut shells are really good at separating oil from water – like a magnet attracting metal. We use them as a natural, reusable filter to remove trace amounts of oil from the water we use to make steam, allowing us to use the same water over and over again. While the idea to use walnut shells for filtration isn’t new, we believe it’s a perfect fit with our creative approach to solving problems and our efforts to continuously improve our environmental performance.

“In this case, we’re using another industry’s byproduct that contributes to our water recycling efforts. This is good for the environment as well as our bottom line,” says Jeffry Pancoast, Chemical Treatment Specialist. “We’re always looking for ways to improve the efficiency of our operations and be environmentally friendly at the same time. Using crushed walnut shells as a natural filter is helping us achieve that.”

At Cenovus, efficient use of water is a big deal to us. That’s because we use a technology called steam-assisted gravity drainage (SAGD) where we heat water to make steam. We inject the steam into our reservoirs deep underground to soften the thick oil so it can be pumped to the surface. When the oil reaches our facilities, it comes mixed with condensed water from the steam, which we then separate out so it can be reused. At that point, there are still small amounts of oil left in the water. And that’s where the crushed walnut shells come in.

We have 40 large filters throughout our oil sands operations using crushed walnut shells to separate water from oil. In 2014, more than 80 percent of the water used to make steam for SAGD operations at our Foster Creek and Christina Lake oil sands projects came from recycled water.

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