Abstract
Bioremediation of hydrocarbons-contaminated soils, using enzymes, is considered an alternative technology for soil remediation, obtaining shorter remediation times, greater removal efficiencies, and less waste generation. The lipases from invasive plants such as castor bean (Ricinus Communis L.) could represent an opportunity for its application in this purpose. This paper reports the results of evaluating enzymatic treatment at different conditions for the remediation of used lubricating oil-contaminated soils. Four assays were performed for the removal of the contaminant in a soil sample: (1) natural attenuation and (2) biostimulation with urea (10% w/v), both used as blanks, (3) enzymatic treatment with lipases at ambient conditions (room temperature, soil pH) and (4) enzymatic treatment with lipases at ideal conditions (temperature 37 °C, pH 4.5). After seven weeks of treatment, removal percentages of 14.23 ± 1.92%, 35.71 ± 5.17%, 14.11 ± 6.71%, and 94.26 ± 1.91%, respectively, were obtained. The degradation of the contaminant was analyzed by Fourier-transform Infrared spectroscopy (FTIR) for each assay. Results show the potential of the lipases for catalyzing the degradation of this contaminant in the soil at ideal conditions, representing an alternative technology to be applied as treatment ex-situ. This paper is the first study known to show the utilization of castor bean lipase for the remediation of hydrocarbons-contaminated soils.