Optimizing a biostimulation process in a soil of Río Gallegos, Argentina, for use in bioremediation of hydrocarbons

Abstract

Biostimulation is an accepted methodology to promote the bioremediation of hydrocarbons in a soil. The objective of this work was to optimize the C: N: P ratio, humidity and concentration and type of hydrocarbons to study the viability of a hydrocarbon biodegradation process in a soil in the city of Río Gallegos, Argentina. Four experiences were developed in microcosms, testing different C:N:P ratios (100:7.5:0.75, 100:5:0.5, 100:2.5:0.25 and 100:1:0.1), relative humidity (0% - 15 %), hydrocarbon concentrations (0% - 5%), and contaminants (gasoline, diesel, lubricating oil and mixtures of them). Monitoring included the mineralization and quantification of hydrocarbons and of heterotrophic and hydrocarbon degrading bacteria. The results showed that the optimal C:N:P ratio was 100:2.5:0.25, with a moisture incorporation range of 10-15% for a soil with 3% hydrocarbons. It was observed that with the application of adequate biostimulation, bioremediation can be effective, estimating that the hydrocarbons in the gasoline may volatilize, generating an inhibition of bacterial activity. The results also showed that when the hydrocarbons of the gasoline are eliminated from the soil 100%, the bacterial activity can recover and develop the biodegradation of the diesel oil, and to a lesser extent those of the oil, providing an auspicious panorama for the application of this large-scale technology in the region.