Buried and surface oil degradation - Evaluating bioremediation to increase PAHs removal through linear mathematical models

A bioremediation approach with tide simulation for buried and surface oil degradation was tested for removal of two, three and four rings polycyclic aromatic hydrocarbons (PAHs). Linear models depicted degradation con-stants of individual PAH as simple additive function of their initial concentrations (C0) in contaminated sand, hydrophobicity, sampling layer and treatment conditions. For all PAHs and treatment conditions, the degrada-tion of oil in buried layers was faster than at the surface. Naturally-occurring microorganisms proved to be efficient for bioremediation of PAHs and were stimulated by fertilizer addition (biostimulation, BS). Bio-augmentation (BA) by addition of a slurry of a native oil-degraders pre-stimulated consortium did not show faster PAH degradation than BS. Degradation was more rapid for PAH present at low C0 and with intermediate hy-drophobicity. Bioremediation of beach sand either with surface or buried crude oil is a cost-effective strategy to clean-up different hydrocarbon families, including persistent ones, such as PAHs.

Automated summary

This study tested a bioremediation approach with tide stimulation to degrade buried and surface oil contamination, focusing on two, three, and four rings polycyclic aromatic hydrocarbons (PAHs). Linear models showed degradation constants of individual PAHs as a simple additive function of their initial concentrations (C0), hydrophobicity, sampling layer, and treatment conditions. Oil degradation in buried layers was faster than at the surface for all PAHs and treatment conditions. Naturally-occurring microorganisms were efficient in bioremediating PAHs and were stimulated by fertilizer addition (biostimulation, BS). Bio-augmentation (BA) with a slurry of pre-stimulated native oil-degrading consortium did not enhance PAH degradation compared to BS. Degradation was more rapid for PAHs with low initial concentrations and intermediate hydrophobicity. Bioremediation of beach sand with either surface or buried crude oil is a cost-effective strategy for cleaning up various hydrocarbon families, including persistent ones like PAHs.