Earthworm-assisted Bioremediation in a Clayey Soil Contaminated by Biodiesel.

Abstract The Success in bioremediation techniques depends on factors such as site characteristics, environmental factors, contaminant nature (temperature, pH, nutrients), presence of suitable biodegradable genes, the contamination nature, etc. Earthworms can aid in these on these factors, through their biological, chemical and physical characteristics, they aerate the soil, improve the nutritional status and help to release the contaminants binding in the soil particles, besides, they help the degrading microorganisms’ dispersion. Biodiesel is a contaminant widely used in the fuel industry, and its production is encouraged. Thus, the aim of this study is analyzed the efficiency of an earthworm species (Eudrilus eugeniae) to remediated a residual clayey soil contaminated with biodiesel, with and without assistance for biostimulated native microorganisms. Therefore, a clay soil was contaminated with biodiesel (24 g / kg) and the ability of the earthworms of the species (Eudrilus eugeniae) to degrade biodiesel with or without biostimulation (cattle manure) for a period of 90 days was analyzed. Earthworms and cow dung have proved to be efficient for remediation processes. Providing 100% degradation at the end of 90 days for "biostimulation and earthworm" and "biostimulation, microorganisms and earthworm" samples. Thus, the use of earthworms contributes to a faster remediation process and, together with microorganisms, they are a more sustainable solution for application in areas contaminated with fuels.