21 March 2012

Oil spills – bugs to the rescue

Dr Moritz Mueller

Many of us will have by now heard about or even been affected by the current oil spill in Miri. And who hasn’t heard about the 2010 catastrophic oil spill in the Gulf of Mexico in which an oil rig exploded and sank? In such cases, we often ask who is to blame for these tragic accidents and who is to pay for the clean-up. These are some questions lawyers will have to find answers to, but in the meantime can we actually clean up oil spills? These are questions science can answer.

Traditional methods involves chemical and physical approaches like putting barriers, called booms, on the surface of the water to prevent the oil from spreading. It is then pumped onto boats or burned but burning releases harmful toxic chemicals into the atmosphere. Burning is efficient and fast but only works if the oil does not get mixed with seawater. If this happens it turns into something called mousse. When mousse is formed, oil loses most of its flammable and more toxic components. This makes mousse much easier to control and collect as it is very sticky, and does not spread like normal oil. To enhance the formation of mousse various chemicals called emulsifiers can be added. The mousse is then removed using skimmers.

However, once the oil reaches shore it will stick to everything and fill every hole it can find. Hoses can be used to spray seawater at high pressure to flush the oil into the water where it can be collected using brooms and removed with skimmers. Besides seawater, chemicals such as the popular BP1100X, can be used.

Today, a more environmentally-friendly and effective approach is bioremediation, a process where biological systems or mostly bacteria and fungi organisms are applied. Bioremediation has become the major mechanism for removing oil residues, especially on affected coasts and shorelines around the world. It is relatively low-cost and can often be carried out on-site. Compared to other methods, it is more promising in cleaning up contaminated soil and water.

The 1989 Exxon Valdez oil spill in Prince William Sound, Alaska, is perhaps one of the most well-known cases. Until today scientists continue to study the affected shorelines to try to understand how a pristine ecosystem responds to and recovers from an oil spill. The contamination was so devastating that practically all available methods, instruments and chemicals were tested. An estimated 100 miles of boom – practically all types of boom available on the market – were deployed. An important observation was that natural cleaning processes on both sheltered and exposed beaches were in many cases effective at degrading oil. However, it took longer for some sections of the shoreline to recover from invasive cleaning methods, hot water flushing in particular, than from the oil itself. Until today some areas have not yet fully recovered. Although it was a dramatic incident, it is somewhat small compared to the 2010 Deepwater Horizon oil spill in the Gulf of Mexico where five million barrels of oil were released. In the Exxon Valdez case about a quarter of a million barrels were released. Of the Deepwater Horizon’s five million, half were dissolved in water, evaporated or became residual. This means that 10 times the amount of oil spilled by Exxon Valdez is still floating around and needs to be removed, although microbes in the ocean will remove it slowly as there are many adapted to eat oil. A limitation of bioremediation is that some bacteria consume only certain types of oil, so different strains have to be deployed for certain types of spills.

In one of our undergraduate biotechnology classes, five types of bacteria isolated from sand collected from the beach in Pasir Panjang near Kuching were able to degrade or eat oil. In another recent final year project, a student isolated another bacterial strain that was effective in consuming oil. One of our postgraduate students isolated 12 fungi from a mangrove plant which grows in a polluted area. Of these, eight were able to absorb copper and zinc. This indicated that they might also be used to help clean up industrial wastewater. In yet another project, we are trying to isolate and identify bacteria from the arsenic-contaminated Tasik Biru in Bau so that they can be used to remove the toxic metal from the lake.

These projects, and many around the world, show that although we can’t see them with our naked eyes, microorganisms are proving that they have the potential to come to the rescue of many of the problems we face today.  So, the solution to cleaning up oil spills and toxic metals might be right outside your doorstep.

Dr Moritz Mueller is a senior lecturer with the School of Engineering, Computing and Science at Swinburne University of Technology Sarawak Campus. He can be contacted atmmueller@swinburne.edu.my