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University of Calgary professors develop method to help clean tailings pond water

By in News
Biofilm on these glass balls helps clean heavy metals from tailings water.
What started in 2009 as a side project with low expectations has quickly yielded impressive results and garnered funding from the National Sciences and Engineering Research Council of Canada.

University of Calgary biochemistry professor Raymond Turner began working with Howard Ceri, a U of C biology professor, on creating a biofilm that would assist in the detoxification and reclamation of some tailings pond water left over after oil sands excavation.

Tailings ponds are large reserves of water runoff that contain toxins and heavy metals. The water in the “ponds,” which are sometimes as large as small lakes, is unsafe for plants and animals to come into contact with.

Turner is not working on providing an instant “solution to the tailings ponds,” as he worries some coverage has painted it. He and his team have grown a biofilm that will assist in the reclamation process of tailings water. The water is taken out of the ponds and treated before being reintroduced into the water cycle.

The problem with this water is that while it has settled into different layers of sediment, there are still many metals and compounds present that make it unsafe.

“We gave the project six months to see if it would work,” Turner said, laughing. “I never thought it would work in a lab…. Where we are now is where we thought we would be in five years.”

Turner and Ceri teamed up to use their respective specializations — Turner has been studying metal-resistant bacteria for 14 years, while Ceri has focused on biofilms — to create a biofilm that would absorb the heavy metals in tailings water without being degraded by them.

Biofilm is a group of microbes working in concert. They occur frequently in nature; tooth plaque is an example.

Turner was initially skeptical of the entire project because it was unknown when they began if they would even be able to create biofilm in a lab setting, but Turner said he was “actually able to grow a fairly good percentage of the community” he was dealing with, growing between 400 and 500 of the 900-odd organisms that were part of the community he was studying.

It was important to the group that they work with biofilm as opposed to the individual organisms that comprise it because many other groups are already working with isolated organisms, Turner explained. Studying a single organism, or even a family of organisms, prevents the resulting research from taking full advantage of biofilm’s ability to degrade dangerous elements in tailings water. The organisms work together in nature for a reason.

Since the project proved successful at creating whole biofilm in a lab, they have worked on making it more metal-resistant and metal-absorbent, testing it by growing it in various conditions — with and without oxygen, and with different amounts of fertilizer.

The different conditions are important because tailings ponds are not uniform. From company to company and even pond to pond, the water can have markedly different levels of alkalinity and acidity, as well as different organic compounds.

“The biofilms we have are incredible hardy,” Turner said. “They are able to accumulate lots of metal.”

Turner likened the biofilm’s function to the ballrooms many fast-food restaurants have for children: the biofilm is grown on small ball-bearings, and dirty water flows through them. As it passes, metals that are in the water stick to the biofilm-laden balls.

Once the biofilm is removed from the balls, it can be run through a smelter to extract the metals, many of which are precious. This makes Turner’s work beneficial not only environmentally, but also economically.

Turner and Ceri have almost concluded their work on this project, but that is simply the first step. They have struck up a partnership with two engineers at the University of Alberta who will soon begin testing the biofilm in a water treatment facility to see how it works in practice.


Photo: Supplied

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