INFLUENCE OF SOIL CHARACTERISTICS ON BIOREMEDIATION OF PETROLEUM-CONTAMINATED SOILS

Soil is one of the key components of a bioremediation system. It is this medium that promotes the growth of both plants and microorganisms. It would, therefore, be expected that research on bioremediation should take into account the influence of the physical and chemical properties of soil, in addition to the type of plants, microorganisms, and related factors. This aspect, however, has not received much attention of researchers in the bioremediation field, which led to development and formulation of the proposed study.

The overall objective of the project was to conduct a series of laboratory experiments with the final goal of developing a new method of bioremediation that, besides other controlling factors, took into account the geochemical and physical characteristics of soils for remediation of petroleum-contaminated sites. The project aimed at identifying the most suitable soil type in terms of its geochemistry and physical properties and determining its control on bioremediation potential of petroleum-contaminated soil, utilizing both microorganisms and plants.

The research utilized a consortia of oil-degrading bacteria commonly found in petroleum-contaminated soils, along with three species of plants – alfalfa, mustard and tall fescue –in various combinations, to evaluate their potential in cleaning up petroleum contamination. Four different soil types – silt, silt loam, loam and sandy loam – were utilized in the lab-scale experiment. It was observed that individually, tall fescue and alfalfa in association with a consortium of pre-isolated oil-degrading bacteria were most effective in remediating contaminated silt-loam. On an average 80% reduction of total petroleum hydrocarbon (TPH) was noted. Field scale studies are being proposed to validate the laboratory results.