Publications

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This document summarizes a three year Laboratory Directed Research and Development (LDRD) program effort to improve our understanding of algal flocculation with a key to overcoming harvesting as a techno-economic barrier to algal biofuels. Flocculation is limited by the concentrations of deprotonated functional groups on the algal cell surface. Favorable charged groups on the surfaces of precipitates that form in solution and the interaction of both with ions in the water can favor flocculation. Measurements of algae cell-surface functional groups are reported and related to the quantity of flocculant required. Deprotonation of surface groups and complexation of surface groups with ions from the growth media are predicted in the context of PHREEQC. The understanding of surface chemistry is linked to boundaries of effective flocculation. We show that the phase-space of effective flocculation can be expanded by more frequent alga-alga or floc-floc collisions. The collision frequency is dependent on the floc structure, described in the fractal sense. The fractal floc structure is shown to depend on the rate of shear mixing. We present both experimental measurements of the floc structure variation and simulations using LAMMPS (Large-scale Atomic/Molecular Massively Parallel Simulator). Both show a densification of the flocs with increasing shear. The LAMMPS results show a combined change in the fractal dimension and a change in the coordination number leading to stronger flocs.

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Chemical disinfection and inactivation of viruses is largely understudied, but is very important especially in the case of highly infectious viruses. The purpose of this LDRD was to determine the efficacy of the Sandia National Laboratories developed decontamination formulations against Bovine Coronavirus (BCV) as a surrogate for the coronavirus that causes Severe Acute Respiratory Syndrome (SARS) in humans. The outbreak of SARS in late 2002 resulted from a highly infectious virus that was able to survive and remain infectious for extended periods. For this study, preliminary testing with Escherichia coli MS-2 (MS-2) and Escherichia coli T4 (T4) bacteriophages was conducted to develop virucidal methodology for verifying the inactivation after treatment with the test formulations following AOAC germicidal methodologies. After the determination of various experimental parameters (i.e. exposure, concentration) of the formulations, final testing was conducted on BCV. All experiments were conducted with various organic challenges (horse serum, bovine feces, compost) for results that more accurately represent field use condition. The MS-2 and T4 were slightly more resistant than BCV and required a 2 minute exposure while BCV was completely inactivated after a 1 minute exposure. These results were also consistent for the testing conducted in the presence of the various organic challenges indicating that the test formulations are highly effective for real world application.

A non-toxic, non-corrosive aqueous foam with enhanced physical stability for the rapid mitigation and decontamination of CBW agents has been developed at Sandia. This technology is attractive for the protection of the Nuclear Weapons facilities as well as for civilian and military applications for several reasons including (1) it requires minimal logistics support, (2) a single decon solution can be used for both CW and BW agents, (3) mitigation of agents can be accomplished in bulk, aerosol, and vapor phases, (4) it can be deployed rapidly, (5) it exhibits minimal health and collateral damage, (6) it is relatively inexpensive, and (7) it has minimal run-off of fluids and no lasting environmental impact. A range of methods including systems that yield desirable properties for fire suppression foams can deliver the foam. Although the foam's effectiveness against CBW agents is well established, the additional capability of being used for fire suppression would provide a dual-use capability. If the foam can suppress and control fires, it could lead to a significant enhancement to the level of protection for critical nuclear weapon facilities in that existing foam-based fire suppression systems could now provide the additional protection of decontamination and CBW agent removal. Fire suppression properties of the foam were investigated with the assistance of Southwest Research Institute Department of Fire Technology in conjunction with EnviroFoam Technologies, Inc., a technology licensee.

The WIPP Case Study describes the compliance monitoring program, record keeping requirements, and passive institutional controls that are used to help ensure the Waste Isolation Pilot Plant (WIPP) will safety contain radioactive waste and indicate dangers and location of the wastes. The radioactive components in the waste are regulated by the U.S. Environmental Protection Agency (EPA) while the hazardous components in the waste are regulated by the New Mexico Environment Department (NMED). This paper addresses monitoring relating to radionuclide containment performance, passive institutional controls, and record keeping over a 10,000-year time frame. Monitoring relating to the hazardous components and the associated regulator are not addressed in this paper. The WIPP containment performance is mandated by release limits set by regulation. Regulations also require the radioactive waste containment performance of the WIPP to be predicted by a ''Performance Assessment.'' The EPA did not base the acceptance of the WIPP solely on predicted containment but included additional assurance measures. One such assurance measure is monitoring, which may be defined as the on-going measurement of conditions in and around the repository. This case study describes the evolution of the WIPP monitoring program as the WIPP project progressed through the planning, site characterization, regulatory promulgation, and eventual operational stages that spanned a period of over 25 years. Included are discussions of the regulatory requirements for monitoring, selection of monitoring parameters, trigger values used to identify unexpected conditions, assessment of monitoring data against the trigger values, and plans for post-closure monitoring. The United EPA established the requirements for Passive Institutional Controls (PICs) for disposal sites. The requirements state the a disposal site must be designated by the most permanent markers, records, and other passive institutional controls practicable to indicate the dangers of the wastes and their location. The PIC Task Force assessed the effectiveness of PICs in deterring inadvertent human intrusion and developed a conceptual design for permanently marking the Waste Isolation Pilot Plant (WIPP), establishing records, and identifying other practicable controls to indicate the dangers of the wastes and their location. The marking system should provide information regarding the location, design, contents, and hazards associated with WIPP. This paper discuss these controls including markers, records, archives, and government ownership and land-use restrictions.

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