A bio-remediation technique involving the use of ‘oil zapping’ bacteria has been employed to clean up the Mumbai shoreline affected by the oil spill that occurred earlier this month.
The oil spill happened when a merchant vessel M V Khalijia collided with a cargo ship MSC Chitra 10 km off the coast of Mumbai. MSC Chitra tilted 15 degrees soon after the collision but there was no loss of life. The cargo ship eventually tilted to about 80 degrees dropping around 250 containers into the sea. Before the spill could be plugged 400 tonnes of oil had leaked into the sea.
MSC Chitra was containing about 2,600 tonnes of oil, 300 tonnes of diesel and 89 tonnes of lubricating oil at the time of the collision. Due to the fear of contamination, the local authorities had warned fishermen against fishing near the shore and had advised people not consume fish for few days. The Bhabha Atomic Research Center had also been ordered not to use sea water for its operations. National media outlets also reported recovery of bottles of harmful pesticides from near the accident site.
The oil has washed ashore in several places and creating a ‘huge mess’. While pollution control vessels sprayed the oil dispersants in the sea, it is also important to clean up the oil washed ashore. Mumbai’s beaches are major tourist attractions and they also support a micro-sized economy of their own with several thousand businesses thriving on the daily inflow of visitors. This makes the cleanup effort even more significant.
For this purpose, the Maharashtra Pollution Control Board has taken the services of The Energy and Resources Institute (TERI) which has developed the oil zapping bacteria.
The oil zapping bacteria was developed over a period of seven years by TERI and the project was supported by the Department of Biotechnology (Government of India) and the Ministry of Science and Technology.
The Oilzapper is essentially a cocktail of five different bacterial strains that are immobilized and mixed with a carrier material (powdered corncob). The Oilzapper feeds on hydrocarbon compounds present in crude oil and oily sludge (a hazardous hydrocarbon waste generated by oil refineries) and converts them into harmless CO2 and water. The Oilzapper is neatly packed into sterile polythene bags and sealed aseptically for safe transport. The shelf life of the product is three months at ambient temperature.
This technology has been successfully used in treating 130,000 tonnes of oily sludge/ oil contaminated soil and is being used by almost all the leading oil companies in India.
The operations have been started at one of the affected beaches and will be repeated at other beaches subsequently. Over 100 volunteers removed the oil-soaked sand from a 1.2 km stretch on the beach and dumped it into treatment ditches 200 meters away from the beach. The oil zapping bacteria was then added to the contaminated sand. The bacteria would take about two months to treat the sand.
While the bio-remediation seems to be the best process to treat the contaminated sludge it does produce carbon dioxide in the process, which can be harmful or harmless according to its rate and quantity of production. Hopefully, the rate of carbon dioxide emission is within limits of the affected areas’ assimilative capacity and it is ‘used up’ in the natural processes.
A news report footage from the site of the accident
Image: ZeNahla (Wikimedia Commons)
The views presented in the above article are author’s personal views and do not represent those of TERI/TERI University where the author is currently pursuing a Master’s degree.
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