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Microorganism selection and performance in bioslurry reactors treating PAH-contaminated soil
1Department of Geosciences, Western Michigan University, Kalamazoo 49008, USA.
Environmental Technology
|October 4, 2002
Summary
Soil slurry-sequencing batch reactors (SS-SBR) effectively removed polycyclic aromatic hydrocarbons (PAH) by promoting biosurfactant production, unlike continuous-flow reactors (CSTR). Reactor operation mode significantly influences microbial consortia and contaminant degradation efficiency.
Area of Science:
- Environmental Microbiology
- Bioremediation Engineering
- Environmental Chemistry
Background:
- Polycyclic Aromatic Hydrocarbons (PAH) are persistent organic pollutants posing significant environmental risks.
- Bioremediation using microbial consortia offers a sustainable approach for PAH-contaminated soil treatment.
- Optimizing reactor conditions is crucial for enhancing microbial activity and contaminant removal.
Purpose of the Study:
- To compare the efficacy of a continuous-flow reactor (CSTR) and a soil slurry-sequencing batch reactor (SS-SBR) for PAH bioremediation.
- To investigate the role of biosurfactant production and microbial consortia in PAH degradation within different reactor types.
- To determine the impact of operational mode switching on reactor performance and microbial community structure.
Main Methods:
- Operation of CSTR and SS-SBR systems for 200 days treating PAH-contaminated soil.
- Quantification of bulk biosurfactant concentrations and PAH emulsification in filtered slurry samples.
- Identification and quantification of specific bacterial species (e.g., Corynebacterium aquaticum, Pseudomonas species) using fatty acid methyl ester (FAME) analysis.
- Monitoring of total PAH removal efficiency and PAH stripping.
Main Results:
- SS-SBR achieved 93% total PAH removal, significantly higher than the CSTR's 66% removal.
- SS-SBR demonstrated substantial biosurfactant production, reaching 4 times the critical micelle concentration (CMC), leading to effective PAH emulsification.
- CSTR showed no measurable biosurfactant production, resulting in lower PAH emulsification and degradation.
- Reversing reactor operation modes led to a complete shift in microbial consortia and reactor performance.
Conclusions:
- SS-SBR operation significantly enhances PAH bioremediation through stimulated biosurfactant production and microbial activity.
- Reactor design and operational strategies are critical determinants of success in bioremediation of PAH-contaminated soils.
- The study highlights the potential for manipulating bioslurry reactor operations to optimize contaminant removal and microbial community dynamics.