More than two months after the oil spill off the Mumbai coast, the contamination at Awas beach in Alibaug has reached permissible levels.
But the contamination level at Colaba’s Navy Nagar continues to be above the danger mark.
The site was most affected by the spill with oil content 381 times higher than the permissible limit of 1,000 parts per million (ppm) at 3,81,000 ppm.
The oil content here has decreased by 50 per cent and it will take two months for it to reach permissible limits, said scientists from Delhi-based The Energy and Resource Institute (TERI), which is carrying out the bio-remediation process for the affected areas.
Two ships had collided off the city’s coast on August 7, spilling furnace oil and contaminating the Colaba coast as well as beaches in Alibaug.
Furnace oil is heavier and more difficult to degrade than crude oil because it contains organo-sulphur compounds that are highly undesirable from the environmental perspective.
The nutrients comprising carbon, nitrogen, phosphorus and trace minerals will be added to microorganisms such as bacteria to break down the oil in the bio-remediation pit.
The bacteria when in contact with oil degrades the pollutants, converts it into carbon dioxide without leaving any harmful residue. This weekend, TERI scientists will land in Mumbai with an additional 15 kg of nutrients that will help quicken the process of oil degradation.
“Thrice since bio-remediation began, we have added more nutrients that will get the microbes more active and degenerate the oil,” said Banwari Lal, director for environment and industrial biotechnology at TERI. “In the absence of these nutrients, oil would not have degraded to 50 per cent.”
At Awas Beach, the clean-up drive has shown faster results. The bio-remediation process has brought the levels of contaminated soil in the pit to the global permissible limit of 1,000 ppm. Before, the level of oil content was 60 times higher at 60,000 ppm.
“The process has responded well in Awas because the oil content was not as high as Navy Nagar,” said Lal.