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Optimizing biodegradation of phenanthrene dissolved in nonaqueous-phase liquids
1Department of Soil, Crop and Atmospheric Sciences, Cornell University, Ithaca, NY 14853, USA.
Applied Microbiology and Biotechnology
|March 1, 1996
Summary
Optimizing bioremediation of phenanthrene in nonaqueous-phase liquids (NAPLs) involves specific microbial inoculums and vigorous agitation. These methods enhance the biodegradation rate and extent, crucial for contaminated site cleanup.
Area of Science:
- Environmental microbiology
- Bioremediation technologies
- Organic pollutant degradation
Background:
- Phenanthrene, a polycyclic aromatic hydrocarbon, often exists in nonaqueous-phase liquids (NAPLs) at contaminated sites.
- Biodegradation of phenanthrene in NAPLs is typically slow and requires optimization for effective remediation.
- Understanding factors influencing microbial degradation is key to developing efficient bioremediation strategies.
Purpose of the Study:
- To optimize the biodegradation of phenanthrene present in various nonaqueous-phase liquids (NAPLs) within soil slurry systems.
- To investigate the impact of microbial inoculum characteristics and physical conditions on phenanthrene mineralization rates.
- To identify effective strategies for enhancing the bioremediation of phenanthrene-contaminated environments.
Main Methods:
- Utilizing soil slurries with phenanthrene dissolved in different NAPLs (dibutyl phthalate, hexadecane, diesel oil, 150 Bright stock oil).
- Employing phenanthrene-degrading microorganisms, with variations in inoculum preparation (growth medium composition, pre-exposure to hydrocarbons).
- Implementing physical process modifications, including vigorous agitation and sequential addition of surfactants and inoculums.
Main Results:
- Addition of adapted phenanthrene-degrading microorganisms significantly increased degradation rates in dibutyl phthalate.
- Vigorous agitation enhanced both the rate and extent of phenanthrene mineralization across various NAPLs.
- Pre-growth of inoculum in hydrocarbon-containing media shortened acclimation periods; intense agitation and adapted inoculums were most effective for hexadecane and diesel oil.
- Sequential addition of surfactant and inoculum improved biodegradation in 150 Bright stock oil and dibutyl phthalate.
Conclusions:
- Optimized microbial inoculation and vigorous agitation are critical for efficient phenanthrene biodegradation in NAPLs.
- The effectiveness of specific bioremediation strategies is influenced by the type of NAPL and microbial inoculum.
- These findings provide improved methods for the bioremediation of sites contaminated with NAPLs, enhancing environmental cleanup efforts.