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Cleaning up a small oil spill

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On August 8, 2010, two merchant ships collided in the Mumbai harbour, spilling oil and hazardous chemicals into the sea. Most of the spill still contaminates the nearby mangrove ecologies. Small sections of the beaches have now been cleaned. According to this report from India Education Review, the whole beach had to be dug up, and the sand transferred to a pit in order to clean it:

Dr Banwari Lal, Director, TERI (The Energy & Resources Institute) said: “We are happy to announce that the bioremediation of oil contaminated soil, using TERI’s Oilzapper technology, at INS Kunjali, a voluntary act by TERI, has been successful. The consequences of an oil spill can be devastating for both the environment and local communities, and we sincerely hope that the concerned regulatory authorities set standard limits for oil contamination in soil in India, which at the moment are not present, so that the polluters can be heavily penalized for such negligence in future. We are thankful to the MPCB and The Indian Navy for their cooperation and making the clean-up operation a success.”

To stave off this environmental disaster, TERI planned to clean around 1 km stretch of the sea beach with the help of volunteers. The non-biodegradables like plastic bottles and polythene as well as few pesticide bottles were segregated. The oily waste including Tar balls were collected to the bioremediation pit (8m X 8m), where the same was mixed with sand and Oilzapper microbes for bioremediation. Around 1000 kg Oilzapper and 20 kg nutrients were applied on the bioremediation site. Zero time samples from the bioremediation site were collected jointly by TERI and MPCB officials and thereafter samples from the bioremediation site as well as control site were collected at regular intervals. Also in the whole operation at INS Kunjali, Navy Nagar, the Oil-contaminated mangroves were not disturbed by TERI Volunteers.

As per the results, it is found that the oil content (in terms of total petroleum hydrocarbon, TPH) in the bioremediation site had been biodegraded from 38.1% (i.e. 3, 81,000 mg/kg) at zero days to 4.19% (i.e. 41,900 mg/kg) after 141 days, indicating 89.00% biodegradation in 141 days after application of Oilzapper. The above TPH of 4.19% is still higher, however it will now gradually biodegrade with time.

To compare the results, a control site was created without any microbial intervention. The control site indicated that the oil content (in terms of total petroleum hydrocarbon, TPH) was degraded from 45.60% (i.e. 4,56,000 mg/kg) at zero day to 41.31% (i.e. 4,31,000 mg/kg) in 141 days indicating very negligible degradation (only 9.41%) without Oilzapper. This indicated the effectiveness of the bioremediation process using Oilzapper.

What happened to the mangroves? Can an ecologically active zone be cleaned by this means without disturbing the ecology even more?

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Written by Arhopala Bazaloides

February 17, 2011 at 3:23 am

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