STATISTICAL EVALUATION OF BIOREMEDIATION OF PETROLEUM-CONTAMINATED SITES BY BACTERIA AND PLANTS

A research project was designed to conduct a series of laboratory experiments with the final goal of developing a new method of bioremediation. The geochemical and physical characteristics of soils were taken into consideration beside other controlling factors. 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. The experiments were conducted according to a full factorial design with three factors (PLANT with 3 levels, SOIL with 4 levels, BACTERIAL ACTIVITY with 2 levels). The Analysis of Variance (ANOVA) was used to perform the statistical analyses of the data.

The contamination degradation reactions followed a second-degree equation pattern. The statistical analyses of data showed presence of strong statistical significance between the soil-plant interaction, plant-bacteria interaction and also between soil-bacteria interaction. It was also 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 soil.