Abstract

Increasing public concern towards petroleum pollution demands for new and more environmentally efficient low-cost strategies for cleaning up contaminated sites. Diesel biodegradation by microbial communities was investigated in artificially contaminated soils by supplementing commercial fertilizers under laboratory conditions. The amounts of oil degraded at each sampling day were determined by the Soxhlet extraction method, the quantities of benzene, toluene, ethyl benzene, and xylene (BTEX) compounds and hydrocarbon content in the treated and non-treated soil samples were determined by gas chromatography-mass spectroscopy. The significant enhancement of diesel degradation was observed soon after the supplementation of fertilizers in loam soil and sea sand, but not in clay soil. The fertilizer supplements stimulated higher degradations, but no significant differences in contaminated sea sand and loam soil after 60 days of incubation period. The inhibitory effect of adding fertilizers was observed in the clay soil. The breakdown of hydrocarbon C>₁₆ were relatively faster than the shorter chain compounds such as C₉. In conclusion, the supplementation of fertilizer stimulates the diesel degradation rate in the contaminated soil and the effects of nutrient supplementation are dependant upon soil types, existing nutrients and microbial populations.

Key words: Diesel, bioremediation, biostimulation, fertilizers