Environmental and Hazardous Waste Research

Protection of human health and the environment is of vital concern to the process industries. There is a continuing demand for new and modified processes that will further reduce air and water emissions of toxic compounds while virtually eliminating solid waste generation. Additionally, many sites have been previously contaminated and must be remediated. Currently, industries, government agencies, and consulting firms have a tremendous number of openings nationwide for chemical engineering professionals in treatment, management, and minimization of waste streams and in remediation of contaminated sites. Via their developed links with the process industries and with federal and state agencies, WSU Chemical Engineering faculty have developed a focused program of research in these areas.

Biological systems appear to be one of the most economical alternatives available to remediate contaminated sites. In cooperation with researchers at Battelle Pacific Northwest Laboratories, ongoing research is directed toward the development of in situ techniques for the biological destruction of chlorinated aliphatic compounds. Bacteria that are indigenous to the site have been shown to degrade CCl4. Ongoing experiments are designed to determine the kinetics of this degradation process under a variety of conditions. Additionally, these kinetics are being incorporated into a mathematical description of the subsurface remediation. This simulation is then being used to determine strategies for the introduction of nutrients to the subsurface such that well life is maximized.

The slow step in the cleanup of subsurface volatile organics to very low desired levels appears to be the desorption of these species from micropores in the associated soil or rock. In a collaborative project with INEEL, investigations are underway concerning the fundamental mechanisms which influence volatile organic desorption rates from soils. Microbalance studies are being used to directly follow amounts adsorbed on simulated soils, which are being prepared to have controlled pores sizes, moisture content, organic content, and surface mineralization. In addition, more traditional column studies are being pursued, as well as large-scale flow model experiments.

Additional research is aimed at determining the nature of the interaction of indigenous bacteria with heavy metal compounds. In multiple projects in collaboration with PNNL and the INEEL, Professors Peyton and Petersen are examining the direct microbial reduction and precipitation of chromium, technetium, and uranium as a means to stop the underground movement of these toxic metals. In addition, the use of biologically generated hydrogen sulfide is being studied as an in-situ method to stop the movement of lead in groundwater. Conditions are being examined where these heavy metal ions can be reduced to a more stable, less toxic form that prevents their migration to more sensitive environments.

For example, we have found that the chromate ion, Cr6+ can be biologically reduced to the much less toxic form. Cr3+. Additionally, Cr3+ will tend to form an insoluble precipitate in the soil, and thus be immobilized.

Halogenated solvents and heavy metals are widespread environmental contaminants that often occur together in soils and groundwater. Interactions between metals and halogenated compounds in soils are poorly understood at the present time and are being studied in collaboration with researchers from the Department of Chemistry and the Department of Crop and Soil Sciences. Competitive adsorption and redox reactions between halogenated solvents and metals such as Cr, Cu and Fe on clay mineral surfaces are investigated by electrochemical techniques. The information obtained will indicate whether these solvents will be degraded under subsoil conditions and whether they, their reaction products, or heavy metal species have significant migration rates in clay soils.

Another recent project focuses on fieldable hand-held sensing packages for environmental monitoring. The technology involves research on ion-selective electrodes, potentiometric enzyme electrodes and other electrochemical componentry to determine levels of metal ions including heavy metals, bacterial contamination, oxygen levels, oxidation/reduction potential and other indicators of water quality. Applications include monitoring of copper ions leached from ship hulls, effects of effluents from industry and liquid wastes from the shipping industry, and determination of effectiveness of environmental remediation efforts.

Because of the proximity of WSU to the Hanford Nuclear Reservation, the Department is engaged in a number of projects in support of environmental cleanup at the Hanford site. In one project, efforts are under way to determine whether organic constituents dissolved in highly alkaline waste waters can be successfully destroyed by taking advantage of the oxidizing capabilities of dissolved nitrate/nitrite salts. The research is aimed at an understanding of the oxidation mechanisms as well as a determination of the optimum processing conditions to achieve total remediation.

In a second project, we are studying the kinetics of the solid state reactions that result when ferrocyanide compounds decompose and react with accompanying nitrate salts. The ferrocyanides, which were used as chelating agents in nuclear fuel reprocessing, are currently stored in waste tanks and since these reactions are highly exothermic, there is an underlying safety problem. A knowledge of kinetics is necessary in order to assess the safety issue and to provide the basis for safe remediation. Remediation of Hanford tank wastes will require the handling of many particulate laden streams. The first problem to be overcome is the removal of the sludges that have formed at the bottom of the many waste tanks. These sludges consist primarily of metal (iron and aluminum) hydroxide/oxide particles with particle sizes in the submicron range. Because of their composition and size changing the chemistry of the suspending medium can alter the colloidal properties of these particles. In cooperation with the contractors at the Hanford site we have been studying the effect that the solution pH has on the ease with which these sludges can be resuspended in a submerged fluid jet. By changing the pH we have been able to control the surface charge, and thus the zeta potential, of the particles forming the sludge. By increasing the surface charge on the sludge particles the rate at which the particles are resuspended in the jet can be dramatically increased.

Once removed from the tanks the resulting slurries will be pumped across the site to centralized treatment facilities. Despite their long history, slurry pipelines are difficult to design and operate. During the slurry transfers planned at Hanford, it will be essential to maintain flow velocities above the critical transport veloc-ity, the value at which solids begin to settle onto the bottom of the pipe. Excessively high pressure drops must also be avoided. The effects of slurry solids concentration, particle size, and particle size distribution on the rheology and flow characteristics are very complex. The available methods for predicting the critical velocity and head loss involve large uncertainties that in turn lead to overdesign of slurry conveying equipment. Once the slurry is delivered, the solids will be separated by settling. Overdesign is again an issue. The focus of our work is on the assessment of published correlations and the de-velopment of improved ones that will reduce these problems.

Participating Faculty
KNona Liddell, Professor
509 335-3710

Reid Miller, Professor
509 335-4001

Jim Petersen, Professor
509 335-1003

Brent Peyton, Assistant Professor
509 335-4002

Bernard J. Van Wie, Professor
509 335-4103

Richard Zollars, Professor
509 335-4332

Recent Publications
R. K. Sani, G. G. Geesey, and B. M. Peyton, "Assessment of Lead Toxicity to Desulfovirio desulfuri-cans G20: Influence of Components of Lactate C Me-dium" Adv. Envron. Res., In press (2001).

J. N. Petersen, and Y. Sun, "An Analytical Solution Evaluating Steady-State Plumes of Sequentially Reactive Contaminants" Trans. Porous Media, 41(3), 287 (2000).

T. P. Clement, B.M. Peyton, T.R. Ginn, and R.S. Skeen, "Modeling bacterial transport and accumulation processes in saturated porous media: a review," Advances in Nuclear Science and Technology, 26, 59 (1999).

J. L. Sherwood, J.N. Petersen, and R.S. Skeen, "Comparative Kinetics For The Biodegradation Of Carbon Tetrachloride By Various Denitrifying Consortia", Biotechnol. Bioeng. 64(3), 342 (1999).

M. A. Rege, D.R. Yonge, D.P. Mendoza, J.N. Petersen, Y. Bereded-Samuel, D.L. Johnstone, W.A. Apel, and J.M. Barnes "Selenium Reduction By A Denitrifying Consortium", Biotechnol. Bioeng. 62(4), 479 (1999).

Y. Sun, J.N. Petersen, J. Bear, T.P. Clement, and B.S. Hooker, "Mod-eling Microbial Transport and Biodegradation in a Dual-Porosity System", Transport in Porous Media 35(1), 49 (1999).

Y. Sun, J.N. Petersen, and T.P. Clement, "Analytical Solutions For Multiple Species Reactive Transport In Multiple Dimensions," J. Contam. Hydrol., 35(4), 429 (1999).

Y. Sun, J.N. Petersen, T.P. Clement, and R.S. Skeen, "Development of Analytical Solutions of Multi-species Transport with Serial and Parallel Reactions", Water Resources Research, 35(1), 185 (1999).

T. P. Clement, B.M. Peyton, T.R. Ginn, and R.S. Skeen, "Modeling bacterial transport and accumula-tion processes in saturated porous media: a review", Advances in Nuclear Science and Technology, 26, 59 (1999).

B. S. Hooker, R. S. Skeen, M.J. Truex, C. D. Johnson, B.M. Peyton, and D. B. Anderson. "In Situ Bioremediation of Carbon Tetrachloride: Field Test Results." Bioremediation Journal, 3, 181 (1998).

Y-Y. Yu, B. J. Van Wie, A. R. Koch, D. F. Moffett, and W. C. Davis, "Preparation and Characterization of Bifunctional biopolymers for Receptor-Based Liposomal Immunosensing," Biotechnology Progress, 14, 310 (1998).

S. Parab, B. J. Van Wie, I. Byrnes, E. J. Robles, B. M. Weyrauch, and T. O. Tiffany, "Modeling & Optimization Studies for a Sequential Flow Based Bio-Analytical Module," Analytica Chimica Acta, 359, 157 (1998).

M. J. Truex, B.M. Peyton, Y.A. Gorby, and N.B. Valentine. "Kinetics of U(VI) Reduction by a Dissimilatory Fe(III)-Reducing Bacterium Under Non-Growth Conditions". Biotechnol. Bioeng., 55(3), 490 (1997).