The dissolution of benzene, toluene, m-xylene and naphthalene from a residually trapped non-aqueous phase liquid under mass transfer limited conditions

1999 ◽  
Vol 36 (3-4) ◽  
pp. 313-331 ◽  
Author(s):  
Sanjay Garg ◽  
William G. Rixey
Keyword(s):  
Mass Transfer ◽  
Aqueous Phase ◽  
Benzene Toluene ◽  
Phase Liquid

Advection–dispersion mass transport associated with a non-aqueous-phase liquid pool

2000 ◽  
Vol 413 ◽  
pp. 49-63 ◽  
Author(s):  
MARIOS M. FYRILLAS
Keyword(s):  
Mass Transfer ◽  
Integral Equation ◽  
Boundary Element Method ◽  
Boundary Element ◽  
Aqueous Phase ◽  
Perturbation Technique ◽  
Transfer Coefficients ◽  
Advection Dispersion ◽  
Phase Liquid ◽  
Element Method

The two-dimensional problem of advection–dispersion associated with a non-aqueous-phase liquid (NAPL) pool is addressed using the boundary element method. The problem is appropriately posed with an inhomogeneous boundary condition taking into consideration the presence of the pool and the impermeable layer. We derive a Fredholm integral equation of the first kind for the concentration gradient along the pool location and compute the average mass transfer coefficient numerically using the boundary-element method. Numerical results are in agreement with asymptotic analytical solutions obtained for the cases of small and large Péclet number (Pex). The asymptotic solution for small Pex, which is obtained by applying a novel perturbation technique to the integral equation, is used to de-singularize the integral equation. Results predicted by this analysis are in good agreement with experimentally determined overall mass transfer coefficients.

Evaluation of surfactant efficiency in remediation on non aqueous phase liquid (NAPL) contaminated soils

2000 ◽  
Vol 42 (1-2) ◽  
pp. 325-330 ◽  
Author(s):  
H. Rubin ◽  
U. Zoller ◽  
D. Dveyrin
Keyword(s):  
Mass Transfer ◽  
Aqueous Phase ◽  
Contaminated Soils ◽  
Soil Column ◽  
Soil Columns ◽  
Water Flows ◽  
Phase Liquid ◽  
Flow Experiments ◽  
Remediation Of Soil

This study represents a possible approach for the determination of the parameters characterizing the efficiency of surfactant mix for the remediation of soil and aquifers contaminated by entrapped non aqueous phase liquid (NAPL). The method incorporates the performance of two sets of experiments and their appropriate analysis. In one set, called the “vessel experiments”, the CMC of the surfactant mix is determined. The second set of experiments is called the “flow experiments”. In this set of experiments soil columns are contaminated by entrapped NAPL. Water flows through these columns with various types of surfactant mix solutions. According to the soil permeabilityvariation and the dissolved NAPL concentration in the water leaving the soil column, the effect of the surfactant mix on the coefficient of mass transfer is determined.

scholarly journals Bacterial Chemotaxis to Naphthalene Desorbing from a Nonaqueous Liquid

2003 ◽  
Vol 69 (10) ◽  
pp. 5968-5973 ◽  
Author(s):  
Aaron M. J. Law ◽  
Michael D. Aitken
Keyword(s):  
Mass Transfer ◽  
Pseudomonas Putida ◽  
Aqueous Phase ◽  
Concentration Gradient ◽  
Bacterial Chemotaxis ◽  
Wild Type ◽  
Concentration Gradients ◽  
Mutant Strains ◽  
Hydrophobic Pollutants ◽  
Phase Liquid

ABSTRACT Bacterial chemotaxis has the potential to increase the rate of degradation of chemoattractants, but its influence on degradation of hydrophobic attractants initially dissolved in a non-aqueous-phase liquid (NAPL) has not been examined. We studied the effect of chemotaxis by Pseudomonas putida G7 on naphthalene mass transfer and degradation in a system in which the naphthalene was dissolved in a model NAPL. Chemotaxis by wild-type P. putida G7 increased the rates of naphthalene desorption and degradation relative to rates observed with nonchemotactic and nonmotile mutant strains. While biodegradation alone influenced the rate of substrate desorption by increasing the concentration gradient against which desorption occurred, chemotaxis created an even steeper gradient as the cells accumulated near the NAPL source. The extent to which chemotaxis affected naphthalene desorption and degradation depended on the initial bacterial and naphthalene concentrations, reflecting the influences of these variables on concentration gradients and on the relative rates of mass transfer and biodegradation. The results of this study suggest that chemotaxis can substantially increase the rates of mass transfer and degradation of NAPL-associated hydrophobic pollutants.

scholarly journals A Screening Model to Predict Entrapped LNAPL Depletion

Water ◽  
2020 ◽  
Vol 12 (2) ◽  
pp. 334
Author(s):  
Elias Hideo Teramoto ◽  
Hung Kiang Chang
Keyword(s):  
Aqueous Phase ◽  
Jet Fuel ◽  
Source Zone ◽  
Saturated Zone ◽  
Depletion Rate ◽  
Benzene Toluene ◽  
Phase Liquid ◽  
Time Required ◽  
Dissolved Phase ◽  
Btex Compounds

Accidental leakage of hydrocarbons is a common subsurface contamination scenario. Once released, the hydrocarbons migrate until they reach the vicinity of the uppermost portion of the saturated zone, where it accumulates. Whenever the amplitude of the water table fluctuation is high, the light non-aqueous phase liquid (LNAPL) may be completely entrapped in the saturated zone. The entrapped LNAPL, comprised of multicomponent products (e.g., gasoline, jet fuel, diesel), is responsible for the release of benzene, toluene, ethylbenzene, and xylenes (BTEX) into the water, thus generating the dissolved phase plumes of these compounds. In order to estimate the time required for source-zone depletion, we developed an algorithm that calculates the mass loss of BTEX compounds in LNAPL over time. The simulations performed with our algorithm provided results akin to those observed in the field and demonstrated that the depletion rate will be more pronounced in regions with high LNAPL saturation. Further, the LNAPL depletion rate is mostly controlled by flow rate and is less sensible to the biodegradation rate in the aqueous phase.

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