Transport of inorganic compounds through compacted clay
Compacted clay liners are widely utilized as leachate barrier in landfills for waste. The main purpose of this research was to study the transport of inorganic compounds through compacted clay. The subjects of interest included the diffusional migration of chemicals at low flow rates, the effective porosity of fine-grained soils, the transport of solutes in unsaturated clays, and the effect of adsorption processes on the transport of reactive solutes. Two clay soils, kaolinite and Lufkin clay, were used in the laboratory column tests and subjected to constant hydraulic gradients of 1 to 50. Inorganic tracers (Cl{sup {minus}} Br{sup {minus}}, K{sup +}, and Zn{sup 2+}) were added to the permeating water as a step input. Conclusions are: (a) the experimental data from soil specimens subjected to various gradients showed that diffusional transport did affect the migration of the tracers in fine-grained media. At low gradients, hydrodynamic dispersion was almost solely related to molecular diffusion rather than mechanical mixing; (b) the breakthrough curves for kaolinite specimens showed that the ratios of effective porosity to total porosity were 0.25 to 1.0. The effect of low effective porosity on transport of the tracers was much greater than that of diffusion; (c) the soils that were not presoaked before tracers were introduced had lower effective porosity and greater dispersion of solutes that did the presoaked soils; (d) no evidence of the existence of a threshold gradient was observed; and (e) the retardation factors predicted from batch equilibrium tests matched the results from column tests poorly, probably due to hydrodynamic effects or geochemical differences between the two soil/solution systems.
- Research Organization:
- Texas Univ., Austin, TX (USA)
- OSTI ID:
- 6652732
- Resource Relation:
- Other Information: Thesis (Ph. D.)
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
BROMIDES
ENVIRONMENTAL TRANSPORT
CHLORIDES
CLAYS
PERMEABILITY
POTASSIUM
ZINC
ADSORPTION
BENCH-SCALE EXPERIMENTS
DIFFUSION
FLOW RATE
HYDRAULIC CONDUCTIVITY
HYDRODYNAMICS
KAOLINITE
LEACHING
POROSITY
S CODES
SANITARY LANDFILLS
SOILS
TIME DEPENDENCE
ALKALI METALS
ALUMINIUM COMPOUNDS
ALUMINIUM SILICATES
BROMINE COMPOUNDS
CHLORINE COMPOUNDS
COMPUTER CODES
DISSOLUTION
ELEMENTS
FLUID MECHANICS
HALIDES
HALOGEN COMPOUNDS
MANAGEMENT
MASS TRANSFER
MECHANICS
METALS
MINERALS
OXYGEN COMPOUNDS
SEPARATION PROCESSES
SILICATE MINERALS
SILICATES
SILICON COMPOUNDS
SORPTION
WASTE DISPOSAL
WASTE MANAGEMENT
540320* - Environment
Aquatic- Chemicals Monitoring & Transport- (1990-)