http://dspace.nitrkl.ac.in:8080/dspace/bitstream/2080/539/1/review-ser-v5-parias.pdf

Surfactant-enhanced remediation of organic contaminated soil and water

Biodegradation of hydrophobic organic compounds in polluted soil is a process involving interactions among soil particles, pollutants, water, and micro-organisms. Surface-active agents or surfactants are compounds that may affect these interactions, and the use of these compounds may be a means of overcoming the problem of limited bioavailability of hydrophobic organic pollutants in biological soil remediation. The effects of surfactants on the physiology of micro-organisms range from inhibition of growth due to surfactant toxicity to stimulation of growth caused by the use of surfactants as a co-substrate. The most important effect of surfactants on the interactions among soil and pollutant is stimulation of mass transport of the pollutant from the soil to the aqueous phase. This can be caused by three different mechanisms: emulsification of liquid pollutant, micellar solubilisation, and facilitated transport. The importance of these mechanisms with respect to the effect of surfactants on bioavailability is reviewed for hydrophobic organic pollutants present in different physical states. The complexity of the effect of surfactants on pollutant bioavailability is reflected by the results in the literature, which range from stimulation to inhibition of desorption and biodegradation of polluting compounds. No general trends can be found in these results. Therefore, more research is necessary to make the application of surfactants a standard tool in biological soil remediation.

Microbiological aspects of surfactant use for biological soil remediation

A compositional simulator for modeling surfactant enhanced aquifer remediation, 1 Formulation

Heavy metal cation retention by unconventional sorbents (red muds and fly ashes)

Multiphase flow and transport modeling in heterogeneous porous media: challenges and approaches

A mathematical model is developed to describe surfactant-enhanced solubilization of nonaqueous-phase liquids (NAPLs) in porous media. The model incorporates aqueous-phase transport equations for organic and surfactant components as well as a mass balance for the organic phase. Rate-limited solubilization and surfactant sorption are represented by a linear driving force expression and a Langmuir isotherm, respectively. The model is implemented in a one-dimensional Galerkin finite element simulator which idealizes the entrapped residual organic as a collection of spherical globules. Soil column data for the solubilization of residual dodecane by an aqueous solution of polyoxyethylene (20) sorbitan monooleate are used to evaluate the conceptual model. Input parameters were obtained, where possible, from independent batch experiments. Calibrated model simulations exhibit good agreement with measured effluent concentrations, supporting the utility of the conceptual modeling approach. Sensitivity analyses explore the influence of surfactant concentration and flushing strategy on NAPL recovery. 45 refs., 6 figs., 3 tabs.

Surfactant-enhanced solubilization of residual dodecane in soil columns. 2. Mathematical modeling

The influence of field-scale heterogeneity on the infiltration and entrapment of dense nonaqueous phase liquids in saturated formations

The influence of field-scale heterogeneity on the surfactant-enhanced remediation of entrapped nonaqueous phase liquids

Impact of surfactant flushing on the solubilization and mobilization of dense nonaqueous-phase liquids.

Sorption processes in subsurface systems are complex, often involving non-linear phase relationships and rate-limited conditions. These processes unquestionably impact reactive solute behavior under typical field scale conditions, and therefore must be considered in attempts to model or otherwise predict contaminant fate and transport in the subsurface. The thoughtful selection of equilibrium and rate models that accurately describe the inherently complex and system-specific dynamics of sorption processes is an imperative for accurate fate and transport modeling.

Timothy J. Dekker

Papers

Surfactant-enhanced solubilization of residual dodecane in soil columns. 2. Mathematical modeling

The influence of field-scale heterogeneity on the infiltration and entrapment of dense nonaqueous phase liquids in saturated formations

The influence of field-scale heterogeneity on the surfactant-enhanced remediation of entrapped nonaqueous phase liquids

Impact of surfactant flushing on the solubilization and mobilization of dense nonaqueous-phase liquids.

Sorption and Retardation of Organic Contaminants in Subsurface Systems: Effects on Transport and Fate