BIOREMEDIATION OF CONTAMINATED SOIL BY SLUDGE OIL USING THE BIOPILES AMELIORATED

Abstract

The bioremediation of contaminated soil by sludge oil from petroleum refinery using amended biopiles through bio-stimulation and/or bio-augmentation was objective of this work. Four biopiles were constructed as follows: B1. control; B2. Bio-supplemented with oil-sludge-degrading bacteria and fungus; B3. Bio-supplemented and bio-stimulated with nutrients (N and P); B4. Bio-supplemented and bio-stimulated with nutrients and rice husk. The study lasted 50 weeks and three different biodegradation stages were found during this period: an initial stage in which the reduction of oil and grease was greatest (up to 10 weeks); a stage with low biodegradation rates of the residue (10-30 weeks), and a late stage (30-50 weeks) in which it was observed an increase of the oily sludge biodegradation after the biopiles were covered with black plastic in thirtieth week. This procedure increased the internal temperature of biopiles and showed the importance of this parameter in the biodegradation process. The bio-stimulation using rice husk improved soil aeration and allowed the development of microorganisms added and increased their metabolic activities; consequently, the oil and grease removal was greater (79.1%). The bacteria and fungus added in biopiles B2 and B3 did not survive, so it is necessary to produce inoculum more competitive and adapted. The biopiles system proved to be a viable technology for the bioremediation of soil polluted by oily sludge from petroleum refinery and the bio-stimulation by addition of materials such as rice husk increases its efficiency.