Laboratory studies of surfactant-enhanced washing of polychlorinated biphenyl from sandy material

Abstract

To assess the suitability of an alcohol ethoxylate surfactant for washing contaminants from soils, the sorption of the surfactant by a sandy soil was studied and the extent of washing of polychlorinated biphenyls (PCBs) from the soil was evaluated. The surfactant adsorption is described by an S-shaped isotherm, consistent with a Langmuir-type monomolecular adsorption followed by adsorption of the surfactant micelles. After only 10 washings with water, the surfactant concentration in the effluent samples decreased from as high as 10000 mg/L to less than 60 mg/L.PCBs could be effectively washed from the sand by using surfactant solutions. After 20 washings about 66, 86, and 56% of the PCBs were washed from the columns by 5000, 10000, and 20000 mg/L surfactant solutions, respectively. This is equivalent to a reduction in PCBs from 1728 mg/kg to about 614, 251, and 769 mg/kg, respectively. The mechanisms responsible for the PCB removal from the sand are presented and discussed.

Influence of a Nonionic Surfactant (Triton X-100) on Contaminant Distribution between Water and Several Soil Solids

“…Although surfactants effectively remove excess nonaqueousphase organic liquids (NAPLs) or solids from water (4)(5)(6)(7)(8)(9) or from soil-water mixtures (10)(11)(12), applications of surfactants to systems where contaminants are subsaturated may yield disparate results, depending on the system condition (13)(14)(15)(16). In the former case, i.e., when a large excess mass of contaminant(s) (e.g., NAPL) exists with a soil or a natural solid, the relatively small amount of the surfactant sorbed is unable to produce a significant change in the overall contaminant uptake, while the surfactant in water may readily enhance the solubilization of the excess contaminant.…”

Effect of a non-ionic surfactant added to the soil surface on the biodegradation of aromatic hydrocarbons within the soil

“…This enhancement even occurs when the substrate is sorbed to solids present in samples of soil and aquifer materials tested in the laboratory, and the stimulation is evident even when an appropriate surfactant is at a low concentration and does not bring about significant desorption (Aronstein and Alexander 1992;Aronstein et al 1991). It is of considerable importance to avoid the use of high concentrations of surfactants, as are sometimes used in soil washing to remove toxicants (Abdul and Gibson 1991;Vigon and Rubin 1989), because of the cost (Doscher 1977) and the possibilities of contaminating the underlying ground-water with the hydrocarbon (Vanloocke et al 1975) or inhibiting the microorganisms that are responsible for biodegradation (Laha and Luthy 1991).…”

Technologies for enhanced remediation of contaminated soils and aquifers: overview, analysis, and case studies

“…Lab-scale column studies have also been conducted on surfactant flushing for removal of sorbed-phase contaminants (e.g. Gannon et aI., 1989;Abdul and Gibson, 1991;Edwards et aI., 1991). More recent studies have evaluated the porescale processes governing nonequilibrium NAPL dissolution during surfactant flushing (Pennell et aI., 1993;1994).…”