[Biodegradation of polycyclic aromatic hydrocarbons and its application to the bioremediation of contaminated soils and sludges].

Polycyclic aromatic hydrocarbons (PAHs) are a group of priority pollutants due to their toxic, mutagenic, and carcinogenic properties. They are found in high concentration in many soils and sludges, mainly those associated with petroleum, gas-production and wood-preservation industries. Application of microorganisms for the remediation of contaminated soils and sludges has gained interest as a promising technique in comparison to the conventional practices of landfilling, incineration or solvent extraction. This paper reviews the controlling variables of the biodegradation of PAHs as well as the use of solid-phase and slurry-phase bioremediation techniques. The acceptance of bioremediation technology requires the demonstration of its efficacy, reliability, predictability of the field performance from lab-scale treatability studies, and economical advantage. Some limitations in the biodegradation of high-molecular-weight PAHs and failures in the control of scale-depending factors (mass transport, spatial heterogeneities, abiotic losses) can reduce its effectiveness. Methodology used for the systematic evaluation of bioremediation is also reviewed.