A case study of bioremediation of petroleum-hydrocarbon contaminated soil at a crude oil spill site

Laboratory and field pilot studies were carried out on the bioremediation of soil contaminated with petroleum hydrocarbons in the Borhola oil fields, Assam, India. The effects of aeration, nutrients (i.e. nitrogen and phosphorus) and inoculation of extraneous microbial consortia on the bioremediation process were investigated. The beneficial effects of these parameters on the bioremediation rate were realised equally in laboratory and field pilot tests. The field tests revealed that up to 75% of the hydrocarbon contaminants were degraded within I year, indicating the feasibility of developing a bioremediation protocol. A complementary computer simulation study was carried out to enhance the understanding of the basic processes and the rate determining factors for bioremediation under the practically relevant conditions of Borhola oil fields. The simulations indicated that due to the high initial contaminant concentrations, the bioremediation process was restricted mostly to the macropores of the system within the period of 1 year and had not penetrated into the soil aggregates sufficiently. Certain shortcomings of the model have been identified and possible refinements suggested. (C) 2002 Elsevier Science Ltd. All rights reserved.