Large Scale Bioremediation of Petroleum Hydrocarbon Contaminated Waste at Various Installations of ONGC. India: Case Studies

Abstract

In situ and ex situ bioremediation of oil contaminated effluent pits, sludge pits, oil spilled land and tank bottom, and effluent treatment plant (ETP) oily sludge was carried out at Ankleshwar, Mehsana, Assam and Cauvery Asset of Oil and Natural Gas Corporation Limited (ONGC), India. The types of contaminant were heavy paraffinic, asphaltic and light crude oil and emulsified oily sludge /contaminated soil. An indigenous microbial consortium was developed by assembling four species of bacteria, isolated from various oil contaminated sites of India, which could biodegrade different fractions of total petroleum hydrocarbon (TPH) of the oily waste to environment friendly end products. The said consortium was on a large scale field applied to the above oil installations and it successfully bioremediated 30,706 tonnes of different types of oily waste. In 65 case studies of different batch size of in situ and ex situ bioremediation processes, the initial TPH content varying from 69.20 to 662.70 g/kg of oily waste has been biodegraded to 5.30 - 16.90 g/kg of oily waste in a range of 2 to 33 months. Biodegradation rate varied in the range of 0.22 - 1.10 Kg TPH /day/m2 area due to the climatic condition of the treatment zone and the type of waste treated. The bioremediated soil was non-toxic and natural vegetation was found to be grown on the same ground. Successful eco-restoration of one large effluent pit of 26,000 m2 area was carried out by cultivation of local fish species after completion of bioremediation. Bioremediation technology has helped ONGC with the management of their hazardous oily wastes in an environment friendly manner. (English) [ABSTRACT FROM AUTHOR]