Laboratory determination of diffusion and distribution coefficients of contaminants using undisturbed clayey soil

1988 ◽  
Vol 25 (1) ◽  
pp. 108-118 ◽  
Author(s):  
R. Kerry Rowe ◽  
Chris J. Caers ◽  
Frank Barone
Keyword(s):  
Diffusion Coefficient ◽  
Clayey Soil ◽  
Distribution Coefficients ◽  
Effective Porosity ◽  
Hydrodynamic Dispersion ◽  
Contaminant Migration ◽  
Mechanical Dispersion ◽  
Simple Theoretical Model ◽  
Test Parameters

This paper describes a technique for determining the diffusion coefficient and the distribution coefficient for contaminants using saturated, intact (undisturbed) clayey soil samples. The technique is illustrated with reference to a number of laboratory tests involving advective-diffusive migration of potential contaminants through an intact clayey soil from Sarnia, Ontario. An important aspect of the proposed technique is that the mass of contaminant in the system is kept constant and so significant decrease in source leachate concentration occurs during each test. A simple theoretical model is used to analyze this case and it is shown that this phenomenon can be used to deduce both the diffusion coefficient and the distribution/partitioning coefficient from a single test. Parameters are deduced for a number of salt solutions passing through the clay from the Sarnia area. On the basis of these tests it is suggested that for the Sarnia soil and advective velocities up to the maximum examined (0.035 m/a), mechanical dispersion does not measurably affect the magnitude of the "coefficient of hydrodynamic dispersion" (i.e., there is no significant dispersion). It is also suggested that the effective porosity corresponds to that deduced from the water content of the soil. Key words: contaminant migration, soil, laboratory study, experimental, analysis, diffusion, advection, clays, groundwater.

Eleventh Canadian Geotechnical Colloquium: Contaminant migration through groundwater—the role of modelling in the design of barriers

1988 ◽  
Vol 25 (4) ◽  
pp. 778-798 ◽  
Author(s):  
R. Kerry Rowe
Keyword(s):  
Key Words ◽  
Fractured Rock ◽  
Distribution Coefficients ◽  
Glacial Till ◽  
Contaminant Migration ◽  
Finite Mass ◽  
Potential Contaminant ◽  
Migration Analysis

The role of analysis in the evaluation and design of barriers is discussed. Factors considered include (i) the mechanisms controlling contaminant migration through barriers; (ii) the determination of diffusion and distribution coefficients; (iii) leachate mounding and the effect of clogging of leachate collection systems upon contaminant migration through barriers; (iv) the importance of considering the finite mass of contaminant available for transport into the soil and a method of modelling the effect of finite mass of contaminant; and (v) examples of how analysis may improve the geotechnical engineer's feel for the effectiveness of potential contaminant attenuation mechanisms in both glacial till deposits and fractured rock. Key words: contaminant migration, analysis, diffusion, advection, clays, groundwater, fractured rock, design, barriers.

Effect of multiple contaminant migration on diffusion and adsorption of some domestic waste contaminants in a natural clayey soil

1989 ◽  
Vol 26 (2) ◽  
pp. 189-198 ◽  
Author(s):  
F. S. Barone ◽  
E. K. Yanful ◽  
R. M. Quigley ◽  
R. K. Rowe
Keyword(s):  
Diffusion Coefficient ◽  
Clayey Soil ◽  
Chemical Constituents ◽  
Soil Layer ◽  
Laboratory Model ◽  
Contaminant Migration ◽  
Adsorption Parameters ◽  
Domestic Waste ◽  
Diffusion Parameters ◽  
Initial Source

This paper describes laboratory model tests involving the placement of domestic landfill leachate on top of a layer of saturated undisturbed clayey soil and allowing chemical constituents to migrate into the soil by diffusion only. During the testing period (15 days), samples from the overlying leachate were regularly collected and analyzed for the chemical constituents of interest (i.e., Cl−, Na+, K+, Mg++, and Ca++). At the end of the test, the soil layer was sectioned to determine the pore-water and adsorbed concentration variations with depth for each species. Mathematical model POLLUTE was then used to back-figure both the diffusion coefficient (D) and the adsorption term (ρK). The measured diffusion coefficients at a temperature of 10 °C were determined to be [Formula: see text], [Formula: see text], and [Formula: see text]. The corresponding adsorption terms were [Formula: see text], [Formula: see text], and [Formula: see text].Ca++ and Mg++, originally predominant on the clay exchange sites, were heavily desorbed to accommodate the adsorption of migrating Na+, K+, and possibly NH4+, causing hardness halo effects that the model could not fit. This behaviour corresponds to that commonly observed at domestic waste sites in southern Ontario.The importance of multiple contaminant migration on diffusion rates was assessed by comparing the leachate models with similar models using a variety of single salts dissolved in distilled water as the source solutions. For the single-salt models, all species considered, including Ca++ and Mg++, behaved in a way that could be described by conventional Fickian theory. A comparison of the diffusion and adsorption parameters obtained from the two types of models indicated that for both Na+ and K+, the measured D and ρK from the leachate models were 20 and 60% lower, respectively, than the values obtained from the single-salt models. For Cl−, the diffusion coefficient obtained from the leachate models was 25% higher than that obtained from the single-salt models.For the Sarnia grey soil used, both D and ρK are significantly influenced by the types and amounts of co-diffusing species present in the initial source solutions. Laboratory tests conducted to determine diffusion parameters for use in design should be run with soils and source solutions chemically identical to those expected in the field. Key words: domestic waste leachate, multiple contaminant migration, clayey soil, diffusion, adsorption, laboratory study.

Atomic absorption determination of Hg (II), Cd (II), and As (III) in natural and waste water after preliminary group preconcentration

2019 ◽  
Vol 85 (2) ◽  
pp. 12-16
Author(s):  
I. V. Saunina ◽  
E. N. Gribanov ◽  
E. R. Oskotskaya
Keyword(s):  
Waste Water ◽  
Atomic Absorption ◽  
High Sensitivity ◽  
Distribution Coefficients ◽  
Neutral Medium ◽  
Atomic Absorption Determination ◽  
Absorption Determination ◽  
Relative Standard ◽  
Preliminary Group

The sorption of Hg (II), Cd (II), and As (III) by natural aluminosilicate is studied. It is shown that the mineral absorbs those toxicants in a rather wide pH range, quantitative extraction of analytes being achieved in a neutral or close to neutral medium (pH values range within 7.0 - 8.0; 6.3 - 7.5; 7.4 - 8.5 for Hg (II), As (III), and Cd (II), respectively). The effect of the time of phase contact on the degree of extraction of elements is shown. The sorption capacity of the mineral in optimal conditions of the medium acidity (0.06 mmol/g for mercury, 0.31 mmol/g for cadmium, and 0.52 mmol/g for arsenic) is determined. The distribution coefficients attain values of aboutnX 103-nX 104. A new combined method for determination of Hg (II), Cd (II), and As (III) in natural and waste water is developed and tested. The method consists in a preliminary group sorption concentration of the analytes by aluminosilicate, desorption of the analytes from the surface of the mineral and their subsequent atomic absorption determination. The correctness of the method is verified in analysis of spiked samples. The method is easy to use and exhibits high sensitivity, reproducibility and accuracy of analyte determination. The relative standard deviation does not exceed 0.13. Economic availability and possibility of using domestic sorption materials are the important advantages of the proposed procedure which can be used in the practice of laboratories monitoring the quality and safety of environmental objects.

TESTS COATINGS UNDER VARIABLE LOADS

2017 ◽  
pp. 95-98
Author(s):  
N. L. Venediktov ◽  
A. N. Venediktov ◽  
I. M. Kovenskiy
Keyword(s):  
Fatigue Testing ◽  
Laboratory Scale ◽  
Kinematic Scheme ◽  
Electrolytic Coating ◽  
Test Parameters ◽  
Experimental Laboratory

The experimental laboratory-scale plant for the fatigue testing of samples with electrolytic coating were designed and constructed. Shows the kinematic scheme and considered the principle of the plant. The dependences for determination of test parameters and the method of testing samples with coatings under variable loads were obtained.

Contaminant migration from sanitary landfill leachate through soil monoliths

1995 ◽  
Vol 32 (7) ◽  
pp. 215-219 ◽  
Author(s):  
Magdelinka Radenkova-Yaneva ◽  
Emilia Kostakeva ◽  
Dimiter Toshev
Keyword(s):  
Clayey Soil ◽  
Sanitary Landfill ◽  
Potential Danger ◽  
Contaminant Migration ◽  
Clay Liners ◽  
Domestic Waste ◽  
Solid Domestic Waste ◽  
Inorganic Substances ◽  
Sanitary Landfills ◽  
Sanitary Landfill Leachate

It is well known that the leachates from solid domestic waste sanitary landfills are heavily polluted with organic and inorganic substances. As they are of a potential danger for the environment, their uncontrolled seepage is avoided in the modern sanitary landfills by means of suitable insulation. This is mostly made of natural materials with a low filtration coefficient. The present paper considers the results of the filtration characteristics, studying natural clayey soil model liners. The leachate contaminants distribution from the sanitary landfill in Sofia (Suhodol) is traced out in different liner depths. The mechanism of pollutant attenuation in the liners is considered. It is found that a part of the leachate components (Fe, Mn, SO42−, PO43−) stays in clayey liners. Besides, as a result of pore colmatation the permeability of the liners is decreased. It is shown that soil monoliths with a proper thickness might serve as a sufficiently safe barrier against leachate filtration in adjacent aquifers. On the base of the results obtained the thickness of the clay liners in the solid domestic waste sanitary landfills could be optimized.

Equilibrium Sorptions in Heterogeneous Ion Exchange Membranes

1992 ◽  
Vol 57 (9) ◽  
pp. 1905-1914
Author(s):  
Miroslav Bleha ◽  
Věra Šumberová
Keyword(s):  
Experimental Data ◽  
Ion Exchange ◽  
Total Content ◽  
Distribution Coefficients ◽  
Exchange Capacity ◽  
Ion Exchange Membranes ◽  
Ion Exchange Capacity ◽  
Equilibrium Sorption ◽  
Inhomogeneity Factor

The equilibrium sorption of uni-univalent electrolytes (NaCl, KCl) in heterogeneous cation exchange membranes with various contents of the ion exchange component and in ion exchange membranes Ralex was investigated. Using experimental data which express the concentration dependence of equilibrium sorption, validity of the Donnan relation for the systems under investigation was tested and values of the Glueckauf inhomogeneity factor for Ralex membranes were determined. Determination of the equilibrium sorption allows the effect of the total content of internal water and of the ion-exchange capacity on the distribution coefficients of the electrolyte to be determined.

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