Bioremdiation of motor oil contaminated soils using biostimulants obtained from sewage sludge

Abstract

The aim of this work was to evaluate the bioremediation capacity of three biostimulants (BS) produced from sewage sludge in a motor oil contaminated soil. Two of the BS (BS1 and BS2) were obtained by a fermentation process with Bacillus licheniformis and the third (BS3) by enzymatic hydrolysis. Motor oil has a high content of polycyclic aromatic hydrocarbons (PAHs) and caused a strong inhibition of the soil microbial activity. The degradation of these PAHs depended on the number of aromatic rings, being observed that hydrocarbons with 5 and 6 aromatic rings were not degraded in non-organically amended soils. The soil dehydrogenase activity as well as the degradation of PAHs increased respect to the non-amended soil when the three BS were used. The effect of these amendments not only depended on the structure of PAHs but also on the chemical composition of BS, being the better results those of the soils amended with the enzymatic hydrolysate.