August 8, 2011 at 9:36 pm #2173
August 1, 2011 – This is not a fish tale
Oilsands by-product filters water clean enough to support aquatic life
At Syncrudes research facility in Edmonton, Warren Zubot still occasionally stops in front of an 80-gallon fish tank of filtered tailings pond water to see how his fish are doing. And they seem to be doing just fine.
Images in this article
It has been more than a year that two koi and two goldfish have been swimming behind the glass. The koi have grown from the size of a thumbnail to the size of a hand. The two goldfish have grown as best as goldfish can. No casualties, no mutant third-eye growth as of yetand none expected because this water has been treated by a new petroleum cokebased water treatment technology.
After initial water testing using this filtering method, everyone was reasonably certain it would provide a happy home for these adorable little non-tetrapod craniates.
While the tank isnt actually a part of Zubots research at Syncrude, it is a compelling demonstration of petroleum cokes ability to purify contaminated water, much like running foul well water through a Brita activated-carbon water filter.
An accidental discovery
Syncrude has been storing petroleum coke in accordance with an Energy Resources Conservation Board directive that requires producers to squirrel away coke for future generations as a potential fuel source. To get the coke to storage, Syncrude mixes it with water recycled from tailings ponds and hydrotransports the slurry from the upgrader to the storage destination. During my work with the Syncrude tailings group, I noticed that the tailings water after it was mixed with coke and pipelined to the Mildred Lake settling basinwas clear and colourless, says Zubot, a senior engineering associate with the massive Syncrude joint venture.
That surprising observation stayed with Zubot. But it wasnt until he was sitting through a water treatment course at the University of Alberta, listening to a segment about activated carbon, that he connected the dots.
It occurred to me there was a possibility that the petroleum coke was actually working like an activated carbon filter that you buy commercially to treat water, he says. Zubot followed up his idea with some water-sample tests and found that was exactly what was happening.
He describes his discovery as accidental, but its a fortunate accident that adds another patent to Syncrudes lengthy roster of some 130 technology U.S. patents to date.
The field study
Water seems to flow through Zubots veins and fuel his imagination. Outside of work, hes a passionate whitewater rafter who has descended wild rivers all over North America. At Syncrude, perhaps less exciting but equally compelling, is his work on water treatment technologies.
Nine years ago, Zubot first put his undergraduate chemistry and civil engineering degrees to work as a contact engineer for Syncrude at its Mildred Lake site. Four years later, he moved to its research centre in Edmonton. Syncrude supported me in doing a Masters degree in water treatment technologies so I went back to school. School was my work and vice versa, he says.
Having completed his Master s in Environmental Engineering in 2009, all of Zubots research today is focused on furthering the development of petroleum coke as a filtering material. Its gone from a paper study to a laboratory study to, this summer, a field-scale study.
Well build a storage cell on our site and fill it with petroleum coke and filter water through it, he says. Well be doing all our tests and experiments on that filtered water to confirm that its not acutely toxic and that its consistent with what we understand based on the experiments weve completed to date.
The exact size of the coke bed is still being determined, but its expected to contain between 1,000 and 2,000 cubic metres of petroleum coke that will filter about 500 cubic metres of tailings process water. Since this is a technology pilot, after being run through the petroleum coke, the water will just be returned to the recycle water system of the tailings pond.
Some of the questions Zubot wants to answer with these experiments are how quickly the water drains out of the coke, whether the coke will plug up with fines and clays (the research to date indicates it wont) and other questions that can best be answered by scaling up.
What adds to petroleum cokes appeal as a filtering material is that it needs no additional processing to do its work. After it completes its effective life, it is returned to storage. In other words, using it as a filter doesnt compromise it as a potential fuel resource for future generations.
The full cycle of construction, tests, analysis and write-up of the pilot will take about a year.
Adding it up: Another step to cleaning up tailings
Syncrude has a number of research trajectories underway targeting different aspects of the quagmire that is oilsands tailings ponds. To this end, it is also working closely with the University of Alberta and its Centre for Oil Sands Innovation to make development more sustainable.
Under the umbrella of tailings pond reclamation, a number of technologies are being developed simultaneously. There are technologies to skim off the duck-killing bitumen layer that floats on tailings ponds, techniques looking at separating the clays and fines from the water, and technologies to remove the dissolved hydrocarbons in the water. The latter is where Zubots work fits in.
Theres also the separation of sand from the tailings water, but thats the least challenging, notes Syncrude spokeswoman Cheryl Robb. Sand drops out of the solution in settling basins very quickly. Were able to remove that sand and use it in the construction of the sites.
As for cleaning up the bitumen surface layer, one direction of investigation is to introduce less bitumen into the tailings in the first place. Another is to skim the bitumen off the surface. (Syncrude piloted a skimming option last summer and is now analyzing the results.)
Clays and fines present a separate vexing problem as they doggedly cling to water molecules, but centrifuge technologies may eventually provide an answer.
Together with Zubots work, all of this research is still unlikely to immediately transform oilsands tailings ponds into quaint boreal ponds, attracting sports fisherman and koi enthusiasts world-over in search of rest, relaxation and a uniquely industrial recreational experience. It does, however, provide Syncrudes management with better tools to manage the business. It offers another use for what is, currently at least, an economically useless upgrading by-product, and it provides the industry with a fighting chance of reigning in the most visible and damning problem in oilsands mining.
August 8, 2011 at 9:40 pm #4981
We made petcoke work as water & solids filter at COP/Venco Moundsville Calciner – long before this Syncrude guy thought about using petcoke to clean up outgoing effluent water!
The guys at the plant used old railcar (took off wheels, put in baffle system & used waste fines as filter to catch storage run-off water which had some coke particles & oil films from volatiles.
We dumped the railcar fines often & sold them as fuel and added fresh fines bake in. Water going into river was cleaner than the river water.
I’ve mentioned to lots of people over years & even posted it on coking.com.
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