Chennai oil spill: An expert explains how best to clean it up
As Chennai continues to grapple with a massive oil spill off its coast, HT spoke to Dr Banwari Lal at The Energy and Resources Institute, on how such a disaster is tackled.india Updated: Feb 06, 2017 16:40 IST
It’s now been a week that authorities have been battling a massive oil spill off the Chennai coast that has raised fears of serious ecological damage.
For an insight into how such an oil spill is contained and neutralised, HT spoke to Dr Banwari Lal at The Energy and Resources Institute (TERI), who has been working on bioremedial methods to clean up oil spills for over two decades. His work focuses on cleaning of crude oil spills and treatment of oily sludge.
His team has developed a technology called Oilzapper, a cocktail of different bacteria that feed on oil. This technology, for which the patent is held by a joint ONGC TERI Biotech Ltd, was used during the last major oil spill near Mumbai in 2010.
How are offshore oil spills cleaned?
In the case of an oil spill in the sea, you have to barricade the area with booms, which are like floating tyre tubes. This arrests the spread of oil due to water currents. The first option is always physical recovery, once the oil is contained to use a vacuum sucker to remove the oil.
What is the role of dispersants?
Only after efforts have been made to physically remove the oil do you resort to chemical dispersants. Most dispersants are man-made chemicals and some are toxic. There are now regulations across the world that require using environmentally-friendly dispersants.
Oil floats on water because of high surface tension, dispersants work by reducing the surface tension between oil and water. So oil would dilute and spread or it will fall to the ocean floor.
There are also bacteria present in the sea too that feed on the oil, breaking it down. But this natural process can take months. Chemical dispersants work immediately, that’s why people use dispersants. People are increasingly saying dispersants are not a solution because the oil won’t be visible but it will remain in the water.
What about oil on beaches?
In the case of the oil spill near Chennai, a clean-up is harder because some of the shorelines are rocky; when the oil sticks to rocks it is harder to clean. For oily sludge on the beach, it is to be removed by putting the contaminated sand on a synthetic liner, which is like a thick rubber sheet. Microbes have to be mixed with the contaminated sand so they can completely degrade the hydrocarbons.
What is Oilzapper?
Oil is a complex mixture, it contains four major fractions of hydrocarbons. We have developed a patented powder, which is light brown in colour, that is a cocktail of four different bacteria that degrade these hydrocarbons.
In the sea too, there are bacteria that feed on oil. Many of these bacteria are slow, so we selected few that are faster and more effective. Once the oil is finished they will die because their food is gone.
We used it during the 2010 oil spill near Mumbai. Because of rough seas, the oil had spread over a large area and on many beaches. We created a space, put a liner and on that, we put the oil-contaminated black coloured sand, then we applied the bacterial powder. The powder can be used both on the sea and also on land.
We have a bigger problem of oil leakage on land than on sea. These can be a result of ruptures of oil pipelines or at oil fields and refineries. We are currently treating 4 lakh meter cube of soil in India with the Oilzapper technology, including sites in the oil fields of Gujarat and Assam.