LARGE SCALE BIOREMEDIATION OF PETROLEUM HYDROCARBON CONTAMINATED WASTE AT INDIAN OIL REFINERIES: CASE STUDIES

ABSTRACT The petroleum industry effluents, oily sludge and oil spills cause a serious threat to the environment as their constituents are toxic, mutagenic and carcinogenic. Safe disposal of these wastes is serious problem. None of the available conventional disposal methods are environment friendly. Biological methods have been well reviewed and acknowledged for remediation of petroleum hydrocarbon contaminated waste (oily waste). An indigenous microbial consortium was developed by assemble of 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 applied on field scale at different oil refineries in India and successfully bioremediated 48,914 tons of different types of oily waste. In 44 field case studies of different batch size of ex situ bioremediation process, the initial TPH content varying from 83.50 to 531.30 gm/kg of oily waste, has been biodegraded to < 10 gm/kg of oily waste in major cases in 2 -12 months. In one refinery due to coastal climate, the bioremediation time was > 20 months. The bioremediated soil was non-toxic and natural vegetation was found to be grown on the same. Bioremediation technology has helped various oil industries for the management of their hazardous oily wastes in environment friendly manner