Development and application of a screening model for evaluating bioenhanced dissolution in DNAPL source zones

Area of Science:

• Environmental Engineering
• Environmental Microbiology
• Geochemistry

Background:

• In-situ bioremediation is a cost-effective technology for dense non-aqueous phase liquid (DNAPL) contaminated sites.
• Effective bioremediation relies on understanding complex transport, mass transfer, and biotransformation processes.
• Predicting the bioenhancement factor, crucial for remedy effectiveness, remains under-researched for real-world conditions.

Purpose of the Study:

• To extend existing bioenhancement factor expressions to zero-order and Monod kinetics.
• To validate these extended models using laboratory and field data.
• To provide practical tools, like nomographs, for predicting bioenhancement in DNAPL source zones.

Main Methods:

• Developed bioenhancement factor expressions for zero-order and Monod kinetics.
• Evaluated model utility with published laboratory and field experimental data.
• Created nomographs to visualize bioenhancement factor dependence on physicochemical properties.

Main Results:

• The extended models accurately predict bioenhancement factors for various experimental scales.
• Nomographs facilitate the assessment of dissolution enhancement in DNAPL source zones.
• Field and column-scale behaviors were successfully captured by the developed approach.

Conclusions:

• The developed bioenhancement factor models and nomographs are valuable for preliminary experimental design and analysis.
• In-situ biomass concentration is a critical factor influencing bioenhanced dissolution.
• This approach enhances the assessment of bioremediation effectiveness for DNAPL-contaminated sites.