Slurry Biocascade for the Enhanced Degradation of Fuels in Soils

摘要

A slurry biocascade for the degradation of fuels in highly contaminated, weathered, clay-rich soils has been developed. In this biocascade approach, different bacterial populations are optimized for sequential steps in the petroleum hydrocarbon degradation. In the first step of the cascade, the simplest fuel components (e.g., n-alkanes) are biodegraded. Then, the soil is transferred to the next steps in the cascade, in which different 'microbial soups' degrade the next groups of hydrocarbons (e.g., the more recalcitrant components, such as multi-ring PAHs). In such a system, each successive step of the cascade maintains a microbial consortium that is optimized to consume organic components of increasing complexity. This 'biological chemostat' has been demonstrated for the degradation of total petroleum hydrocarbons (TPH). When compared to the batch approach (in which the microbial population must constantly adapt to a depleting and more recalcitrant carbon source), the biocascade was shown to be much more effective both in terms of the rate and degree of degradation. Pilot-scale studies have demonstrated the feasibility of the cascade biotreatment approach in off-the-shelf commercial bioreactors. The results from these bench and pilot studies and the lessons learned are discussed.