Hydrocarbons, surfactant remediation

Common surfactants such as Tween, Triton,5 and sodium dihexyl sulfosuc-cinate, among many others, have been used to extract organic compounds from soil. In the field, they have been particularly useful in the remediation of soils contaminated with halogenated organic compounds, oils, and other hydrocarbon compounds [24],... 

Microcat (meaning microbial catalysts) products constitute a bioremediation technology used on wastewaters, sludges, and soils. Microcat products include specialized microbial cultures, nutrients, and surfactants to remediate organic contaminants such as petroleum hydrocarbons. The products used in site remediation include ... 

The CRS process is a commercially available closed-loop technology that is designed to separate hydrocarbon contaminants from soil without the use of surfactants or other additives. According to the vendor, this technology can be used to remediate petroleum production facilities, refineries, and other industrial sites including airports, military bases, tank farms, fuel storage and transportation terminals, and waste sites. 

This technology, along with similar technologies such as surfactant flushing, was originally developed in the petroleum industry to improve hydrocarbon recovery. Its use in environmental apphcations such as aquifer remediation is relatively new, with most laboratory and field trials having been carried out during the past 8 years. 

Micro-foam, or colloidal gas aphrons have also been reportedly used for soil flushing in contaminated-site remediation [494—498], These also have been adapted from processes developed for enhanced oil recovery (see Section 11.2.2.2). A recent review of surfactant-enhanced soil remediation [530] lists various classes of biosurfactants, some of which have been used in enhanced oil recovery, and discusses their performance on removing different type of hydrocarbons, as well as the removal of metal contaminants such as copper and zinc. In the latter area, the application of heavy metal ion complexing surfactants to remediation of landfill and mine leachate, is showing promise [541]. 

L.J. Pinto and M.M. Moore, Release of Polycyclic Aromatic Hydrocarbons from Contaminated Soils by Surfactant and Remediation of this Effluent by Penicillium spp. Environ. Toxicol. Ghent. 19(7), 1741-1748, June (2000). 

All the systems described thus far require relatively high salinity, which is considered to be critical in soil remediation processes [60]. Another approach for effective microemulsification of organic liquids is the use of co-surfactants. Sodium mono- and dimethyl naphthalene sulphonate were found to be effective co-surfactants in formulations with Aerosol OT (sodium bis(2-ethylhexyl) sulphosuccinate) for diverse chlorinated hydrocarbons and their mixtures between 15 and 25°C [60, 61]. All types of microemulsions could be obtained with this approach. 

Saichek RE, Reddy KR (2005b). Surfactant-enhanced electrokinetic remediation of polycyclic aromatic hydrocarbons in heterogeneous subsurface environments. Journal of Environmental Engineering Science 4(5) 327-339. 

Cosolvent-enhanced electrokinetic remediation of chlorinated pesticides has yet to be explored. Few studies have shown enhancements in the transport of polycyclic aromatic hydrocarbons (PAHs) when cosolvents were used (Maturi and Reddy, 2008 Reddy and Saichek, 2003). The potential success of cosolvents depends on their ability to mobilize the HOCs and to increase the EOF. It was shown that 10% n-butylamine generated the greatest EOF, followed by 20% n-butylamine and water (Maturi and Reddy, 2008). The sorption of solvents to the soil matrix may not be as high as the surfactants, which cause a better solubilization with the same amount of electro-osmotic transport. 

Beside the presentation of the SMART concept, the objectives of this paper are (i) to examine how organic contaminant transport is influenced by properties of natural aquifer material and (ii) to show how surfactants may enhance the remediation of sites contaminated with polycyclic aromatic hydrocarbons (PAH). This is done in an exemplary way by applying the transport model to a simplified field-scale remediation scenario where Phenanthrene (PHE) and the non-ionic surfactant Terrasurf G50 (TG50) are considered as solutes. 

Finkel, M. Liedl, R. Teutsch, G. (1999) Modelling surfactant-enhanced remediation of polycyclic aromatic hydrocarbons. Environment Modelling Software 14, 203-211. 

Metal removal from a sandy soil contaminated with 1710 mg/kg of Cd and 2010 mg/kg of Ni was later evaluated [3]. Maximum removal was obtained by foam produced by 0.5% rhamnolipid solution, after 20 pore volumes. Removal efficiency for the biosurfactant foam was 73.2% of Cd and 68.1% of Ni. For the biosurfactant liquid solution, 61.7% Cd and 51.0% Ni were removed. This was superior to Triton X-100 foam which removed 64.7% Cd and 57.3% Ni and liquid Triton X-100 which removed 52.8% Cd and 45.2% Ni. Distilled water removed only 18% of both Cd and Ni. Concentrations of 0.5,1.0 and 1.5% rhamnohpid at pH values of 6.8,8 and 10 were also evaluated but did not show significant effects. For a 90% foam quaUty, the average hydraulic conductivity was 4.1 X 10 cm/s, for 95%, it was 1.5 X 10 cm/s and for 99%, it was 2.9 X 10 cm/s. Increasing foam quality decreases substantially the hydraulic conductivity. All these values are lower than the conductivity of water at 0.02 cm/s. This higher viscosity will allow better control of the surfactant mobihty during in situ use. Therefore, rhamnohpid foam may be an effective and non-toxic method of remediating heavy metal, hydrocarbon... 

The effects of electrokinetic treatment have been studied in the presence of other components, such as surfactants like Triton X-114. This has yielded a hydrocarbon removal percentage of about 49 % after 6 h and 66 % after 24 h. This compares with individual chemical and electrokinetic treatments after 6 h of treatment at 1.5 mL min , showing 12 % and 35 % removal, respectively. The coupled system was very successful, although inconvenient in the permanency of Triton X-114 in the soil following remediation [18]. 

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