Density-modification displacement using colloidal biliquid aphron for entrapped DNAPL contaminated aquifer...

Area of Science:

• Environmental Science
• Chemical Engineering
• Geochemistry

Background:

• Dense nonaqueous phase liquids (DNAPLs) pose significant environmental risks.
• Understanding DNAPL displacement and density modification is crucial for effective remediation.
• Current methods for DNAPL removal often leave residual contaminants.

Purpose of the Study:

• To investigate the mechanisms of density modification and displacement of tetrachloroethylene (PCE) using colloidal biliquid aphrons (CBLA).
• To evaluate the efficiency of CBLA in removing DNAPLs from contaminated environments.
• To compare the effectiveness of CBLA-based remediation with traditional surfactant flushing.

Main Methods:

• Batch, column, and sandbox experiments were conducted.
• Density modification and PCE removal were monitored.
• Viscosity ratios and phase analysis were employed to understand displacement mechanisms.

Main Results:

• Less than 1% of PCE was retained in the column and sandbox under optimal conditions.
• PCE density in the effluent was reduced to below that of water (0.74-0.96 g/cm³).
• CBLA reduced residual PCE mass 165 times more effectively than surfactant flushing, with no risk of downward migration.

Conclusions:

• CBLA is a potent density modifier for DNAPLs like PCE.
• The high viscosity ratio of CBLA to PCE is a key factor in the displacement process.
• This density-modification displacement technique offers a promising solution for remediating entrapped DNAPLs in aquifers.