Experimental Investigation of a Pilot-Scale Concerning Ex-Situ Bioremediation of Petroleum Hydrocarbons Contaminated Soils

Abstract

The soil samples were taken from the site of a former oil products depot from an industrial area (Romania). The soil samples taken were analyzed from a physical and chemical point of view: texture, ph, soil micronutrient content, metals concentration and petroleum hydrocarbon concentration (PHCs). The soil contaminated with TPH (4280 mgkg-1) was disposed in the form of a pile (LxWxH:3000x1400x500 mm). Experiments a pilot-scale were conducted over 12 weeks at constant pH (7.5–8), temperature (22–32oC), nutrient contents C/N/P ratio 100:10:1, soil aeration time (8 hour/day) and moisture (30%). Samples were taken every two weeks for the monitoring of the TPH and the microorganisms content. During experiment every two weeks were added microoganisms (Pseudomonas and Bacillus). Results of the analyzes regarding the concentration of PHCs were revelead a linear decrease of the concentration of PHCs after only two weeks of treatment. This decrease in concentration was also achieved in the following weeks. Following the analysis performed on the model at the pilot scale regarding the depollution process, it can be concluded that a soil contaminated with petroleum hydrocarbons can be efficiently depolluted by performing an aeration of 8 h/day, adding microorganisms Pseudomonas and Bacillus to ensure the conditions for increasing in the total number of germs (colony forming units–CFU) from 151x105 to 213x107 CFU/gram of soil, after 12 weeks of soil treatment - the depollution efficiency achieved is 83%.