Facts and challenges on hydrocarbons bioremediation

Abstract

[Excerpt] The intense activity of the oil industry generates substantial amounts of contaminated wastes and wastewaters. Moreover, accidental oil spills occur frequently, causing severe damages in the marine environment and in the soil. Subsurface soil contamination is generally caused by oil leakages from underground storage tanks and transport pipelines that can further lead to groundwater contamination. To date, common techniques for remediation of petroleum-contaminated environments include physical removal, washing by cosolvents or surfactants, thermal desorption, electrokinetic movement of contaminants and oxidation/reduction via chemical agents. Biological technologies can be an alternative to the more aggressive physicochemical methods, as bioremediation exploits the metabolic diversity of microorganisms and their ability to degrade organic contaminants. Aerobic bioremediation is frequently preferred over anaerobic processes, due to faster rates of hydrocarbons activation and biodegradation [1]. However, in subsurface environments oxygen is generally scarce and anoxic conditions prevail. Anaerobic microorganisms can biodegrade hydrocarbons coupled to the reduction of nitrate, iron(III), sulfate or under methanogenic conditions [2]. In situ bioremediation of hydrocarbons at anoxic conditions has not been extensively studied, despite the broad occurrence of these contaminants in the subsurface. Reduced knowledge on the catabolic mechanisms and microbial communities involved in anaerobic hydrocarbons biodegradation has limited this approach, and needs further research. [...]