Contaminants removal remediation

REMOVAL OF CONTAMINANTS AS REMEDIAL ACTIONS 18.8.1 Removal and Recovery of Free Product... 

One conclusion from the SITE evaluation was that the cost of the technology is small compared to the benefits of enhanced remediation and the reduced number of wells needed to complete the remediation (D10054P, p. iv). In addition, the DOE concluded that hydraulic fractioning decreased the time required to cleanup a site due to more efficient contaminant removal. As a result, the maintenance and operating costs over the life cycle of the project also decreased (D183771, section 5 p. 2). 

Selective colloid mobilization enhances removal of strongly sorbed contaminants, increasing remediation efficiency. 

At a Superfund site in Battle Creek, Michigan, DVE was nsed as part of a larger SVE system to treat 26,700 yd of VOC-contaminated soil. Excluding before-treatment cost elements, total remediation expenses at the site were 1,645,281. This valne translates to 62/yd of soil treated, or 37/lb of contaminant removed. Before-treatment costs at the site eqnaled 535,180. The EPA notes that overall costs at this site were higher becanse of the extensive sampling and analysis that were required (D13945R, pp. 225, 227 D125053, p. 871). 

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]. 

Natural attenuation by itself, however, often is not sufficient to achieve a desired extent or rate of contaminant removal from an aquifer. In these instances, one remedial option may be to enhance the natural rate of biodegradation of pollutant chemicals in the aquifer. This strategy, called in situ bioremediation, is considered to be one of the most attractive remedial techniques from a cost perspective, because many of the high costs associated with pumping and treating groundwater or excavating contaminated aquifer material are avoided. Furthermore, the potential exposure of cleanup workers to pollutant chemicals is reduced if many of the contaminants are mineralized while still in the aquifer. 

Figure 1.1. Schematic of the implementation of in situ electrochemical remediation systems. The electrodes are inserted into the soil and a direct electric field is applied to the contaminated site, which indnces the transport of the contaminants toward the electrodes. The electrode solntions are pumped, treated, and circulated for contaminant removal. Selected electrode conditioning solutions may be used to induce favorable chemistry at the electrodes and in the soil.

T vo types of remediation activities are possible under CERCLA removal and remedial actions. Remedial actions are longer-term permanent solutions to hazardous waste contamination. Removal actions are short-term cleanup actions that address immediate threats at a site. They are conducted in response to an emergency situation (e.g. to avert an explosion, to clean up a hazardous waste spill, or to stabilize a site until a permanent solution can be found). Electrokinetic remediation technologies are likely to be part of a CERCLA remedial action. There are nine general criteria that must be addressed by those wishing to implement electrokinetic technologies as part of CERCLA remedial actions ... 

A wide range of technologies are available for the remediation of contaminated sites, and the applicability of a particular method depends on the site conditions, the type and extent of contamination, and the extent of remediation required. In some situations, it may be possible to rely on natural decay or dispersion of the contaminants. Removal of contaminants from a site for disposal in an approved disposal facility has frequently been used. However, the costs involved in removal can be extremely high. On-site burial can be carried out by the provision of an acceptable surface barrier or an approved depth of clean surface filling over the contaminated material. This may require considerable earthwork. Clean covers are most appropriate for sites... 

Soil washing in ex situ (above ground) processing is a proven remediation technology that is also robust and versatile. Previous field demonstrations have shown that this technology can achieve high levels of contaminant removal at relatively low costs. As the technology matures, the cost of treatment may be expected to decrease. 

A number of methods can be employed to monitor remedial progress, including the use of monitoring wells, groundwater analysis, and effluent vapor analysis. Selected case studies are summarized in Table 14.1 and in this section to provide information on expected contaminant removal using air sparging systems. 

Buckley, K.R., and W.D. Vijayan. 1992. A process for contaminant removal and waste volume reduction to remediate groundwater containing certain radionuclides, toxic metals, and organics. U.S. Department of Energy DOE/CH-9201 Final Rep. Contract no. 02112415. U.S. Department of Energy, Washington, DC. 

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