Microcosm evaluation of bioaugmentation and biostimulation efficacy on diesel‐contaminated soil

BACKGROUND: Diesel oil broad utilisation has led to its dispersion in the environment. In this work, biostimulation and biostimulation coupled with indigenous bioaugmentation were investigated for the bioremediation of soil artificially contaminated with diesel oil. RESULTS: Soil microcosms were prepared and monitored. The most effective strategy and the influence of glucose addition, both in soil or during the biomass “enrichment” phase, were evaluated by means of respirometric analyses, microbial counts and residual contaminant concentration measurements. The respirometric activity was always higher in all the microcosms contaminated with diesel oil than in the biotic controls. The presence of the contaminant did not inhibit the microbial activity. The microbial counts performed on diesel oil medium showed that the contaminant was prevalently biodegraded by the indigenous bacterial species. In terms of diesel oil degradation, similar results were obtained in biostimulated and bioaugmented microcosms, a degradation percentage in the range of 65-70% after 34 days was achieved. The addition of glucose in soil, though favouring the growth of microorganisms, did not improve the degradation of contaminant. CONCLUSION: In this work, biostimulation, with no addition of a primary substrate, was the simplest and most cost effective strategy for the biodegradation of diesel oil.