Carpathian Journal of Earth and Environmental Sciences

Colombia has had large oil spills in old oil extraction areas and in oil infrastructure (associated to attacks and illegal valves) causing serious damages to natural ecosystems. In this study laboratory pilot tests were carried out on the bioremediation of oil contaminated soils from Silvania in Colombia. The objective of the current investigation is assessing the effect of Tween 80 surfactant in the degradation of TPH in the bioremediation (Biostimulation and Bioaugmentation) treatments in anaerobic conditions. Two Bioaugmentation treatments and three Biostimulation treatments were proposed: Bioaugmentation (B), Surfactant Bioaugmentation (SB), Biostimulation (Bs), Surfactant Biostimulation (SBs) and Surfactant Biostimulation with D-Limonene (SBsDL). For the Bioaugmentation treatments, the bacterial density was increased using composting and in Biostimulation treatments nutrients and amendments were applied. Additionally, Natural Attenuation treatment (NA) and Control treatment (C) were carried out. After 90 days the degradation of TPH the results for each treatment are Control (53.8%), NA (57.7%) B (65.4%), SB (69.2%), Bs (75.0%), SBs (76.9%) and SBsDL (76.9%). The results indicate that bioremediation treatments with surfactant have higher percentages of biodegradation of TPH, both B and Bs treatments show a decrease in the remaining TPH compared with the Natural Attenuation Treatment. The increase of the microbial population and the stimulation with nutrients in the bioremediation treatments under anaerobic conditions has a positive effect to decrease the number of hydrocarbons present in a contaminated site. The laboratory tests revealed that up to 76.9% of the oil contaminants were degraded within 90 days, indicating the feasibility of developing a bioremediation protocol on a large scale.