Bacteria could clean up tar sand pollution

Toxins that can normally last in the environment for up to 10 years can be broken down in a matter of days using a mix of microbes, according to researchers from the University of Essex.

Microbiologists from the university used a mix of bacteria to completely degrade acidic compounds from crude oil and tar sands in just a few days.

The researchers’ achievement is significant, as so-called tar sand deposits are believed to be the world’s largest source of oil. Extracting and refining oil from tar sands and super heavy crudes, however, produce large amounts of highly concentrated toxic by-products.

The most toxic of these are a mixture of compounds known as naphthenic acids, which are resistant to breakdown and persist as pollutants in the water used to extract oil and tar. This water is stored in large tailing ponds, and the number and size of these ponds are growing daily. One estimate puts the amount of naphthenic acids-contaminated water in Athabasca, Canada, alone, at around 1 billion cubic metres and rising.

Consequently, any efforts to safely exploit tar sand deposits will depend upon finding environmentally friendly ways to eliminate the resulting pollutant.

‘The chemical structures of the naphthenic acids we tested varied,” said PhD researcher Richard Johnson. “Some had more side branches in their structure than others. The microbes could completely break down the varieties with few branches very quickly; however, other more complex naphthenic acids did not break down completely, with the breakdown products still present. We are now piecing together the degradation pathways involved which will allow us to develop more effective bioremediation approaches for removing naphthenic acids from the environment.”