Enhancement of Hydrocarbon Removal in a Clay and Drilling-Waste Polluted Soil

Abstract

The application of biological processes in restoring oil polluted sites is growing due to their efficiency in removing different classes of pollutants. The aim of this study was to determine the ability of microorganisms present in a drilling-waste polluted soil (36,200 mg TPH kg −1 soil) to remove weathered hydrocarbons under stimulated and non-stimulated soil conditions. The hypothesis under study was whether petroleum hydrocarbons removal could be enhanced by manipulating C/N ratio, water content and addition of three agroindustrial wastes. A Box-Behnken design was employed to evaluate the effect of each variable. Results demonstrated that, for orange peels and banana trunk treatments, the variable with the largest effect (p < 0.01) on hydrocarbon removal was the C/N ratio, indicating that higher ratio (100/3) improved removal (79.5-82%). The largest effect (p < 0.001) on hydrocarbon removal for pineapple wastes was observed with higher water content (60%) achieving the highest removal (89%). After 90 days of experimentation, the type of agricultural waste and the agricultural waste/soil ratio were not statistically significant in any treatment. However, their addition was important relative to non-stimulated soil, which showed a hydrocarbon removal of 17%. Data reported in this study showed the application of bioremediation in clay and drilling waste-polluted soils.

Effect of fertilizer formulation and bioaugmentation on biodegradation and leaching of crude oils and refined products in soils

“…Bulking agents have frequently been used during bioremediation to improve soil structure, break up and mix the soil, lower the bulk density and increase porosity to facilitate better transfer of oxygen, water and nutrients into the soil and enhance removal of oily products [30][31]. Bulking agents also increase the surface area of contaminated soil exposed to microbial processes by increasing the surface to volume ratio [31,32].…”

“…However, no major increase in TPH biodegradation compared to the slow release fertiliser microcosms was observed between week 8 and 12 (Figure 4), indicating that the slow TPH decline after the first month represents the degradation of the less readily biodegradable hydrocarbons in TBS and OBM, rather than a N or P limitation. The extent of hydrocarbon biodegradation is strongly dependent on the nature of the contaminant, the soil chemistry and the partitioning of specific compounds into the aqueous phase where the biological uptake occurs readily [5,31,35,36,37]. In some cases, bioavailability is relatively unimportant, while in others it may be critical.…”

Effect of sulphur species on the hydrocarbon biodegradation of oil sludge generated by a gas processing facility

“…The organic extracts were free asphaltenes, purified by hexane precipitation. Concentrated samples (1 ll) were analysed by FID-gas chromatography (Agilent Technologies, model 6890) under the conditions described by Rojas-Avelizapa et al (2006), but increasing the duration of the last step (290°C for 25 min). Helium was used as the carrier gas at a flow rate of 1.4 ml min -1 .…”