Mark D. Tucker

Reduction of Cr, Mo, Se and U by Desulfovibrio desulfuricans immobilized in polyacrylamide gels

Intact cells of Desulfovibrio desulfuricans, immobilized in polyacrylamide gel, removed Cr, Mo, Se and U from solution by enzymatic-mediated reduction reactions. Lactate or H2 served as the electron donor and the oxidized Cr(VI), Mo(VI), Se(VI) and U(VI) served as electron acceptors. Reduction of the oxidized metal species resulted in the precipitation of solid phases of the metals. Metal removal efficiencies of 86–96% were achieved for initial concentrations of 1 mM Mo, Se, and U and 0.5 mM Cr. Insoluble metal phases accumulated on both the surface and the interior of the polyacrylamide gel. In column tests conducted for U removal, effluent concentrations less than 20 μg L−1 were achieved with initial concentrations of 5 mg L−1 and 20 mg L−1 U and residence times from 25–37 h. The enzymatic reduction of Cr, Mo, Se, and U by immobilized cells of D. desulfuricans may be a practical method for removing these metals from solution in a biological reactor.

Removal of U and Mo from water by immobilized Desulfovibrio desulfuricans in column reactors

Intact cells of Desulfovibrio desulfuricans were immobilized in polyacrylamide gel and used to remove soluble U and Mo from water by enzymatically mediated reduction reactions in column reactors. Formate or lactate served as the electron donor and oxidized U(VI) and Mo(VI) species served as electron acceptors. Greater than 99% removal efficiencies were achieved for both metals with initial concentrations of 5 mg/L U and 10 mg/L Mo. Hydraulic residence times in the columns were between 24 and 36 h. Sulfate concentrations as high as 2000 mg/L did not inhibit reduction of U or Mo in the columns. However, nitrate inhibited uranium reduction at concentrations near 50 mg/L and inhibited molybdenum reduction at concentrations near 150 mg/L. The results indicate that enzymatic reduction of U and Mo by immobilized cells of D. desulfuricans may be a practical method for removing these contaminants from solution in continuous-flow reactors.

Treatment of waste containing EDTA by chemical oxidation

Abstract Ethylenediaminetetraacetic acid (EDTA) is a chelating agent that has been extensively used to enhance the solubilization of heavy metal cations and release of EDTA contributes to environmental problems. EDTA is recalcitrant to microbial metabolism and chemical oxidation is considered a possible method of remedial treatment. The use of the commercially available process of MIOX Corporation generates mixed oxidants on site and this solution is markedly effective in the destruction of the chelating characteristic and the decarboxylation of EDTA. When measuring the release of C-14 from carboxyl labeled EDTA, the mixed oxidant solution was comparable to the Fentons reaction over a broad pH range. The presence of Mn 2+ , Cr 3+ , or Fe 3+ at levels equal to that of EDTA stimulated the rate of EDTA decomposition; however, the rate of EDTA breakdown was inhibited when the concentration of Cr 3+ or Mn 2+ exceeded the concentration of EDTA. The treatment of Co 2+ –EDTA or Cu 2+ –EDTA with mixed oxidants in the presence of ultra violet light resulted in the loss of chelation ability of EDTA. In the absence of chelated metals, over 75% of the chelation property of a 70 mM EDTA solution was destroyed in 45 min. The reaction products resulting from the use of mixed oxidants added to EDTA were non-toxic to bacteria and should not contribute to additional environmental problems.

A Systematic Methodology for Selecting Decontamination Strategies Following a Biocontamination Event

Decontamination and recovery of a facility or outdoor area after a wide-area biological incident involving a highly persistent agent (eg, Bacillus anthracis spores) is a complex process that requires extensive information and significant resources, which are likely to be limited, particularly if multiple facilities or areas are affected. This article proposes a systematic methodology for evaluating information to select the decontamination or alternative treatments that optimize use of resources if decontamination is required for the facility or area. The methodology covers a wide range of approaches, including volumetric and surface decontamination, monitored natural attenuation, and seal and abandon strategies. A proposed trade-off analysis can help decision makers understand the relative appropriateness, efficacy, and labor, skill, and cost requirements of the various decontamination methods for the particular facility or area needing treatment--whether alone or as part of a larger decontamination effort. Because the state of decontamination knowledge and technology continues to evolve rapidly, the methodology presented here is designed to accommodate new strategies and materials and changing information.

A Biological Decontamination Process for Small, Privately Owned Buildings

An urban wide-area recovery and restoration effort following a large-scale biological release will require extensive resources and tax the capabilities of government authorities. Further, the number of private decontamination contractors available may not be sufficient to respond to the needs. These resource limitations could create the need for decontamination by the building owner/occupant. This article provides owners/occupants with a simple method to decontaminate a building or area following a wide-area release of Bacillus anthracis using liquid sporicidal decontamination materials, such as pH-amended bleach or activated peroxide; simple application devices; and high-efficiency particulate air-filtered vacuums. Owner/occupant decontamination would be recommended only after those charged with overseeing decontamination-the Unified Command/Incident Command-identify buildings and areas appropriate for owner/occupant decontamination based on modeling and environmental sampling and conduct health and safety training for cleanup workers.

Development of Biodegradable Isosaccharinate-Containing Foams for Decontamination of Actinides: Thermodynamic and Kinetic Reactions between Isosaccharinate and Actinides on Metal and Concrete Surfaces

The objective of this project is to develop fundamental information that will lead to the development of a new, more environmentally acceptable technology for decontaminating Pu and other actinides. The key component of this technology is isosaccharinate (ISA), a degradation product of cellulose materials that is biodegradable and binds strongly with tetravalent actinides. We are developing fundamental constants for (1) the effect of a wide range in pH and Ca concentrations on the speciation and thermodynamic reactions of ISA and (2) thermodynamic and kinetic reactions of ISA with tetravalent actinides and other competing ions such as Fe(III). We have successfully formulated and tested several ISA containing foams and gels for their effectiveness in removing tetravalent actinides from concrete and steel surfaces. These data along with a comprehensive thermodynamic mo del developed for Np(IV) and Ca(II) and applicable to a wide range in pH, ISA concentrations, and ionic strengths, will be presented.

Joint Sandia/NIOSH exercise on aerosol contamination using the BROOM tool.

In February of 2005, a joint exercise involving Sandia National Laboratories (SNL) and the National Institute for Occupational Safety and Health (NIOSH) was conducted in Albuquerque, NM. The SNL participants included the team developing the Building Restoration Operations and Optimization Model (BROOM), a software product developed to expedite sampling and data management activities applicable to facility restoration following a biological contamination event. Integrated data-collection, data-management, and visualization software improve the efficiency of cleanup, minimize facility downtime, and provide a transparent basis for reopening. The exercise was held at an SNL facility, the Coronado Club, a now-closed social club for Sandia employees located on Kirtland Air Force Base. Both NIOSH and SNL had specific objectives for the exercise, and all objectives were met.

Quick start users guide for the PATH/AWARE decision support system.

The Prioritization Analysis Tool for All-Hazards/Analyzer for Wide Area Restoration Effectiveness (PATH/AWARE) software system, developed by Sandia National Laboratories, is a comprehensive decision support tool designed to analyze situational awareness, as well as response and recovery actions, following a wide-area release of chemical, biological or radiological materials. The system provides capability to prioritize critical infrastructure assets and services for restoration. It also provides a capability to assess resource needs (e.g., number of sampling teams, laboratory capacity, decontamination units, etc.), timelines for consequence management activities, and costs. PATH/AWARE is a very comprehensive tool set with a considerable amount of database information managed through a Microsoft SQL (Structured Query Language) database engine, a Geographical Information System (GIS) engine that provides comprehensive mapping capabilities, as well as comprehensive decision logic to carry out the functional aspects of the tool set. This document covers the basic installation and operation of the PATH/AWARE tool in order to give the user enough information to start using the tool. A companion users manual is under development with greater specificity of the PATH/AWARE functionality.

Enhanced Micellar Catalysis LDRD

The primary goals of the Enhanced Micellar Catalysis project were to gain an understanding of the micellar environment of DF-200, or similar liquid CBW surfactant-based decontaminants, as well as characterize the aerosolized DF-200 droplet distribution and droplet chemistry under baseline ITW rotary atomization conditions. Micellar characterization of limited surfactant solutions was performed externally through the collection and measurement of Small Angle X-Ray Scattering (SAXS) images and Cryo-Transmission Electron Microscopy (cryo-TEM) images. Micellar characterization was performed externally at the University of Minnesotas Characterization Facility Center, and at the Argonne National Laboratory Advanced Photon Source facility. A micellar diffusion study was conducted internally at Sandia to measure diffusion constants of surfactants over a concentration range, to estimate the effective micelle diameter, to determine the impact of individual components to the micellar environment in solution, and the impact of combined components to surfactant phase behavior. Aerosolized DF-200 sprays were characterized for particle size and distribution and limited chemical composition. Evaporation rates of aerosolized DF-200 sprays were estimated under a set of baseline ITW nozzle test system parameters.

Enhancing activated-peroxide formulations for porous materials: Test methods and results

During an urban wide-area incident involving the release of a biological warfare agent, the recovery/restoration effort will require extensive resources and will tax the current capabilities of the government and private contractors. In fact, resources may be so limited that decontamination by facility owners/occupants may become necessary and a simple decontamination process and material should be available for this use. One potential process for use by facility owners/occupants would be a liquid sporicidal decontaminant, such as pHamended bleach or activated-peroxide, and simple application devices. While pH-amended bleach is currently the recommended low-tech decontamination solution, a less corrosive and toxic decontaminant is desirable. The objective of this project is to provide an operational assessment of an alternative to chlorine bleach for low-tech decontamination applications activated hydrogen peroxide. This report provides the methods and results for activatedperoxide evaluation experiments. The results suggest that the efficacy of an activated-peroxide decontaminant is similar to pH-amended bleach on many common materials.