Polycyclic aromatic hydrocarbon behavior in bioactive soil slurry reactors amended with a nonionic surfactant

Area of Science:

• Environmental Science
• Microbiology
• Soil Science

Background:

• Polycyclic aromatic hydrocarbons (PAHs) are persistent organic pollutants found in creosote-contaminated soils.
• Surfactants like Tween 80 are explored for enhancing PAH bioavailability for bioremediation.
• Understanding surfactant-soil-PAH interactions is crucial for effective soil remediation strategies.

Purpose of the Study:

• To investigate the impact of Tween 80 on the bioavailability of PAHs in soil systems.
• To assess the microbial utilization of Tween 80 in creosote-contaminated soil.
• To evaluate the effectiveness of Tween 80 in mobilizing PAHs for bioremediation.

Main Methods:

• Experiments were conducted using soil-free and dense-slurry systems with creosote-contaminated soil.
• The bioavailability of PAHs and microbial utilization of Tween 80 were monitored.
• Solubilization ratios and partition coefficients were measured to assess micelle stability and PAH mobilization.

Main Results:

• Dispersed-micelle-phase PAHs were not readily bioavailable to indigenous microbes.
• Microbes preferentially consumed Tween 80 as a carbon source (16-18% of dose).
• High Tween 80 concentrations (>20 g/L) were needed for PAH mobilization due to soil sorption, and released PAHs were rapidly re-sorbed or associated with surfactants, limiting biological access.

Conclusions:

• Tween 80 alone is ineffective in enhancing PAH bioavailability for bioremediation under the tested conditions.
• Microbial degradation of Tween 80 destabilizes micelles, reducing its efficacy.
• Effective bioremediation strategies require careful consideration of surfactant sorption and microbial interactions with both surfactant and contaminants.