Use of surfactants and slurrying to enhance the biodegradation in soil of compounds initially dissolved in nonaqueous-phase liquids | JoVE Visualize

Use of surfactants and slurrying to enhance the biodegradation in soil of compounds initially dissolved in nonaqueous-phase liquids

M H Fu¹, M Alexander

¹Department of Soil, Crop, and Atmospheric Sciences, Cornell University, Ithaca, NY 14853, USA.

Applied Microbiology and Biotechnology|July 1, 1995

View abstract on PubMed

Summary

Enhancing the biodegradation of hydrophobic compounds in nonaqueous-phase liquids (NAPLs) is crucial. Surfactants and soil slurrying show potential, but effectiveness varies with the specific compound and NAPL. Vigorous agitation can significantly boost degradation rates.

Area of Science:

Environmental microbiology
Bioremediation of contaminated soil

Background:

Hydrophobic organic compounds in nonaqueous-phase liquids (NAPLs) exhibit slow biodegradation in soil.
Understanding factors influencing NAPL biodegradation is essential for effective environmental cleanup strategies.

Purpose of the Study:

To investigate methods for enhancing the biodegradation of hydrophobic organic compounds within NAPLs.
To evaluate the impact of surfactants, NAPL identity, and agitation on biodegradation rates and extent.

Main Methods:

Experiments involved mineralizing phenanthrene, di-(2-ethylhexyl) phthalate (DEHP), and biphenyl in various NAPLs.
The study assessed the effects of adding specific surfactants (Triton X-100, Alfonic 810-60, Tergitol 15-S-9, Tween 80) and soil slurrying.
Biodegradation rates and extent were monitored under different conditions, including varying agitation levels.

Main Results:

Surfactant addition did not consistently enhance phenanthrene degradation in hexadecane or dibutyl phthalate.
Soil slurrying increased phenanthrene mineralization in hexadecane but not dibutyl phthalate.
Certain surfactants (Triton X-100, Alfonic 810-60, Tergitol 15-S-9) stimulated phenanthrene degradation in heptamethylnonane at concentrations below their critical micelle concentrations.
Slurrying and specific surfactants (Alfonic 810-60, Triton X-100) enhanced DEHP biodegradation in dibutyl phthalate.
Vigorous agitation or small NAPL volumes significantly improved DEHP and biphenyl degradation in acclimated soil slurries.

Conclusions:

The effectiveness of enhancing NAPL biodegradation is highly dependent on the specific hydrophobic compound and the NAPL matrix.
Soil slurrying and the strategic use of certain surfactants, particularly below their critical micelle concentrations, can promote biodegradation.
Physical factors like vigorous agitation and optimized NAPL volume are critical for maximizing the degradation of recalcitrant compounds like DEHP and biphenyl.