Enhanced Bioremediation of Heavy Oil Contaminated Soil by Bacterial Consortium Amended with Biosurfactant

Abstract

The bioremediation of the heavy oil is often limited by high viscosity and low bioavailability. The aim of the present study was to find methods for enhancing rates of heavy oil biodegradation. Biodegradation of heavy oil by mixed bacterial consortium (BC) amended with Glycolipid biosurfactant (GBS) was monitored in shake flask conditions, which showed a significant reduction of the heavy oil at two concentrations [1% and 2% (w/v)] of the liquid culture media compared with that of no addition of the GBS at the end of 180 hours. Then different enhancement combinations of non-sterile soil (NS) from Liaohe oil fields were carried out using BC and GBS. During biodegradation process of 60 days, heavy oil degradation, total microbial counts, dehydrogenase activity (DHA) and pH were measured. Maximum heavy oil degradation occurred in the treatment NS+BC+GBS with degradation rates approximately 72%, and the increase of degradation rate was more pronounced than that of the treatment NS+BC. Moreover, in the treatment NS+BC+GBS, the microorganism population kept 108 CFU/g of soil higher than those of other treatments, and the DHA increased significantly. The results indicated that GBS has great potential for increasing the interfacial surface area between water and oil, consequently, bacteria growth and oil degradation rates being promoted as well as the solubility and bioavailability of heavy oil. Thereby, additive BC and GBS had significant positive effects on the bioremediation of the soil contaminated with heavy oil.