Biomass plug development and propagation in porous media

Area of Science:

• Microbiology
• Biotechnology
• Environmental Science

Background:

• Exopolymer-producing bacteria offer potential for soil modification in enhanced oil recovery and bioremediation.
• Understanding biomass plug formation and propagation is crucial for effective application of this technology.

Purpose of the Study:

• To elucidate the mechanisms of biomass plug development and propagation in porous media using exopolymer-producing bacteria.
• To identify distinct phases of plugging behavior and the underlying physical processes.

Main Methods:

• Packed-bed and micromodel experiments were conducted to simulate plugging in porous media.
• Leuconostoc mesenteroides was utilized, with dextran (exopolymer) production controlled by varying carbon sources.
• Pressure drop dynamics were monitored to characterize different plugging phases.

Main Results:

• Three distinct pressure phases were observed: exopolymer-induction, plugging, and plug-propagation.
• Pressure changes correlated with biomass distribution, where flow channels within biofilms became restrictive.
• Biomass yielded like a Bingham plastic at maximum pressure, initiating plug propagation driven by nutrient flow.

Conclusions:

• Exopolymer production is the primary mechanism driving all three phases of plugging in porous media.
• Yield stress becomes an additional significant mechanism during the plug-propagation phase.
• This research provides critical insights into microbial plugging mechanisms for biotechnological applications.