Remediation of Deep Vadose Zone Radionuclide and Metal Contamination: Status and Issues

Abstract

Table S.1. (contd) Technology Description State of Development Development Path Electrokinetic mobilization and recovery Application of an electric field in the soil induces contaminant mobilization through electromigration, electroosmosis, or electrophoresis. Particularly applicable to lowpermeability sediments. Method has been implemented in selected shallow vadose zone contaminant areas. Ability to deploy at depth and/or over large areas may be an issue. This area is not considered a high priority for R&D. Identify suitable chemical enhancements for particular applications if considering deployment on a site-specific basis. Hybrid electrokinetic delivery of treatment chemicals Mobilization of fluids to target areas by application of electric fields. Laboratory testing performed for reduction of chromate. Control of subsurface chemical conditions is critical. This area is a high priority for R&D applied to remedial design. Recommend further R&D for chemical fixation in low-permeability sediments and enhancement of other remediation systems. Hybrid electrokineticpermeable reductive barrier Electrical fields can enhance the reductive effectiveness of permeable barriers. Laboratory testing performed for reduction of chromate. Placement of electrodes and barriers in deep vadose zone may be problematic. May be useful in areas of low-permeability, high saturation sediments. This area is not considered a high priority for deep vadose zone R&D. Assess local geochemical and hydrological conditions when considering deployment on a site-specific basis. Enhanced Volatilization Volatilization by heating is limited to zero-valent mercury (Hg), organic mercury species, and potentially iodine-129. Hg(II) would have to be reduced to Hg(0) for volatilization. Conceptually simple but only laboratoryscale evaluations were found. This area is not considered a high priority for R&D. Assess local geochemical and hydrological conditions when considering deployment on a site-specific basis. viii Table S.1. (contd) Technology Description State of Development Development Path Enhanced Sorption Chemical manipulation of solution or solid surfaces to retard transport. Addition of materials to increase sorptive surfaces (altered mineralogy or particle size) or to alter aqueous speciation can retard chemical movement. Mature concept. Less fundamental information on desorption processes than for sorption. This area is not considered a high priority for R&D applied to remedial design. Fundamental research on desorption processes would be valuable. xiii Table S.1. (contd) Technology Description State of Development Development Path Hydraulic Control Caps and covers Caps and covers control infiltration and recharge, thus, reducing contaminant transport to the water table. Covers may be combined with other fixation technologies. Cap and cover technologies are well established but may need engineering for site-specific applications. This area is not considered a high priority for deep vadose zone R&D. Consider deployment on a site-specific basis. A...

Basic Research Needs for Environmental Management

“…For additional details on the technologies listed beyond the discussion provided above, see NRC (1999) and the references contained therein. For additional discussion on technologies that can be applied to remediate deep vadose zone metals and radionuclides, see Dresel et al (2008).…”

Transport of stabilized iron nanoparticles in porous media: Effects of surface and solution chemistry and role of adsorption

“…Zero valent iron (ZVI) nanoparticles have received considerable attention for in-situ remediation of contaminated soil and groundwater [1][2][3]. ZVI nanoparticles hold great potential for diverse remediation applications, from reductive dechlorination [4] to immobilization of metals and radionuclides [5,6] in the subsurface. Based on a preliminary survey conducted by the U.S. Environmental Protection Agency (USEPA) [7], ZVI had been the most employed particulate materials used for in situ remediation.…”

Development the Economical Chemical Treatment Plant for Chromium Recovery From Tannery Waste Water

“…Pre-tanning chemicals,these chemicals are not fully reacting with the skins or fiber and finally they are not retained by the skins of leather. Pre-tanning chemicals after performing their functions are discharged into the wastewaterwith high rate of pollution rate [3]. Tanning chemicals are reacted with the collagen fiber protein of the skin and then convert it into leather finished form.…”