Researchers create method of cleaning toxins from oil sands

The method makes use of biofilms and could eventually be used in tailings water treatment plants that return clean water to the river system.

Oil sand is a naturally occurring mixture of sand, clay or other minerals, as well as water and bitumen, which is a heavy and extremely viscous oil that must be treated before it can be used by refineries to produce usable fuels such as gasoline and diesel. There are major reserves in Venezuela, the US and Russia, but the Athabasca deposit in Alberta, Canada, is the largest and most developed reserve.

Oil sand development uses a vast amount of water and, even though it is recycled multiple times, the recycling concentrates the toxins and metals left over from extracting and upgrading the bitumen, resulting in controversial tailings ponds that are a significant risk to the environment.

The current research project aimed at tackling the problem is a collaboration between biologists at Calgary University and engineers at Alberta University.

‘We’ve isolated biofilms that are indigenous to the oil sands environment and highly tolerant to the stress associated with toxins and metals found in tailings water. Those consortia of biofilms are able to slowly detoxify the water,’ said Prof Raymond Turner of Calgary University.

Turner and his team are actively growing biofilms on the support material to test in bioreactors, which are being developed by professors and their graduate students in the civil and environmental engineering department at Alberta University.

‘By altering the growth conditions and exposing the biofilms to different stressors, we could select for or against certain species and we began to learn how we could manipulate the biofilms to get the metabolic activities and characteristics we were looking for,’ Turner said.

The ultimate goal, he added, is to develop tailings water treatment plants for all the oil sands operations. ‘The plant would take all tailings water, completely clean it and then return it to the river system — just like wastewater in Calgary is cleaned and returned to the Bow River.’