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Laboratory screening tests were performed to select microorganisms for their ability to destroy nitrates and carbon tetrachloride in Hanford groundwaters. The microorganisms were subsequently tested in bench-scale experiments to determine the fundamental kinetic constants for denitrification with acetate. The microorganisms were also used as the inoculum for the pilot-scale bioreactor system, which was designed, constructed, and operated in FY 1988. The bench-scale denitrification kinetic data were analyzed using two rate models. The best fit was obtained using a first-order expression. The kinetic constants determined in the bench-scale experiments were later used to set operating parameters for the pilot-scale bioreactor test. The pilot-scale bioreactor system consisted of a 50-L continuous-stirred tank bioreactor, a 280-L clarifier, associated feed components, and a data acquisition and control system. The pilot plant was designed as a module for ease of installation and to facilitate relocation for on-site demonstration testing. The pilot-scale bioreactor was installed and operated in FY 1988, but steady-state operating data are not yet available. Preliminary denitrification data show destruction of nitrate to concentrations less than drinking water standards. A preliminary engineering evaluation was also completed in FY 1988 that examined the engineering feasibility of biodenitrification for the UO{sub 3} Plant process condensatemore » through microorganism laboratory testing, development of flowsheets, and equipment size and cost estimates. 15 refs., 16 figs., 8 tabs.« less |
