Advanced Technology Section semiannual progress report, April 1-September 30, 1977. Volume 1. Biotechnology and environmental programs. [Lead Abstract]

Research efforts in six areas are reported. They include: centrifugal analyzer development; advanced analytical systems; environmental research; bioengineering research;bioprocess development and demonstration; and, environmental control technology. Individual abstracts were prepared for each section for ERA/EDB. (JCB

Design of fluidized-bed, biological denitrification systems

Many commercial processes yield nitrate-containing wastewaters that are being discharged to the environment because traditional recovery or disposal methods are economically unacceptable. The anticipated discharge limits (i.e., 10 to 20 g (NO/sub 3//sup -/)/m/sup 3/) being considered by many states will not allow continued release of these wastewaters. The new discharge standards can be met economically by use of the fluidizied-bed, biological denitrification process. Research and development studies were conducted with 0.05-, 0.10-, 0.20-, and 0.50-m-diam fluidized-bed bioreactor systems. Feed nitrate concentrations were in the 0 to 10,000 g (NO/sub 3//sup -/)/m/sup 3/ range. Using the data from these studies, rate expressions were developed for the destruction of nitrate as a function of nitrate concentration. Methods were also developed for sizing bioreactors and biomass control systems. The sizing methods for fluidized-bed denitrification systems are described, and support systems such as sampling and analysis, instrumentation and controls, utilities, and bacteria storage are discussed. Operation of the process is also briefly discussed to aid the designer. Using the methods presented in this report, fluidized-bed, biological denitrification systems can be designed to treat nitrate wastewater streams

Ba(OH)/sub 2/. 8H/sub 2/O process for the removal and immobilization of carbon-14. Final report

The airborne release of /sup 14/C from various nuclear facilities has been identified as a potential biohazard due to the long half-life of /sup 14/C (5730 years) and the ease with which it may be assimilated into the biosphere. At ORNL, technology has been developed for the removal and immobilization of this radionuclide. Prior studies have indicated that /sup 14/C will likely exist in the oxidized form as CO/sub 2/ and will contribute slightly to the bulk CO/sub 2/ concentration of the gas stream, which is air-like in nature (approx.300 ppM/sub v/ CO/sub 2/). The technology that has been developed utilizes the CO/sub 2/-Ba(OH)/sub 2/.8H/sub 2/O gas-solid reaction with the mode of gas-solid contacting being a fixed bed. The product, BaCO/sub 3/, possesses excellent thermal and chemical stability, prerequisites for the long-term disposal of nuclear wastes. For optimal process operation, studies have indicated that an operating window of adequate size does exist. When operating within the window, high CO/sub 2/ removal efficiency (effluent concentrations 99%), and an acceptable pressure drop across the bed (3 kPa/m at a superficial velocity of 13 cm/s) are possible. Three areas of experimental investigation are reported: (1) microscale studies on 150-mg samples to provide information concerning surface properties, kinetics, and equilibrium vapor pressures; (2) macroscale studies on large fixed beds (4.2 kg of reactant) to determine the effects of humidity, temperature, and gas flow rate upon bed pressure drop and CO/sub 2/ breakthrough; and (3) design, construction, and operation of a pilot unit capable of continuously processing a 34-m/sup 3//h (20-ft/sup 3//min) air-based gas stream

Advanced biological treatment of aqueous effluent from the nuclear fuel cycle

Many of the processing steps in the nuclear fuel cycle generate aqueous effluent streams bearing contaminants that can, because of their chemical or radiological properties, pose an environmental hazard. Concentration of such contaminants must be reduced to acceptable levels before the streams can be discharged to the environment. Two classes of contaminants, nitrates and heavy metals, are addressed in this study. Specific techniques aimed at the removal of nitrates and radioactive heavy metals by biological processes are being developed, tested, and demonstrated. Although cost comparisons between biological processes and current treatment methods will be presented, these comparisons may be misleading because biological processes yield environmentally better end results which are difficult to price. The fluidized-bed biological denitrification process is an environmentally acceptable and economically sound method for the disposal of nonreusable sources of nitrate effluents. A very high denitrification rate can be obtained in a FBR as the result of a high concentration of denitrification bacteria in the bioreactor and the stagewise operation resulting from plug flow in the reactor. The overall denitrification rate in an FBR ranges from 20- to 100-fold greater than that observed for an STR bioreactor. It has been shown that the system can be operated using Ca/sup 2 +/, Na/sup +/, or NH/sub 4//sup +/ cations at nitrate concentrations up to 1 g/liter without inhibition. Biological sorption of uranium and other radionuclides (particularly the actinides) from dilute aqueous waste streams shows considerable promise as a means of recovering these valuable resources and reducing the environmental impact, however, further development efforts are required

Tapered fluidized-bed bioreactor: an improved device for continuous cultivation

The bioreactor concept utilizing a tapered fluidized bed has shown considerable promise for use in bioprocesses where the biological agents can be immobilized on a fluidizable solid phase, but the operating characteristics of such a reactor are not yet fully understood. A simple mathematical model (steady state, plug flow conditions) has been developed and tested with experimental data, and calculated values compare favorably with experimental values. A more complete and presumably more valid mathematical model incorporating void volume changes and particle size distribution is being developed

Logic-based Agent Communication Protocols

An agent communication protocol specifies the rules of interaction governing a dialogue between agents in a multiagent system. In non-cooperative interactions (such as negotiation dialogues) occurring in open societies, the problem of checking an agent's conformance to such a protocol is a central issue. We identify di#erent levels of conformance (weak, exhaustive, and robust conformance) and explore, for a specific class of logic-based agents and an appropriate class of protocols, how to check an agent's conformance to a protocol a priori, purely on the basis of the agent's specification

A Social Approach to Communication in Multiagent Systems

Abstract. This paper aims at defining the semantics of Agent Communication Languages (ACLs) in terms of changes in the social relationships between agents, represented in terms of social commitments. We take commitment to be a primitive concept underlying the social dimension of multiagent systems, and define a basic artificial institution that provides agents with the means to affect the commitment network that binds them to each other. Two different approaches are adopted for the presentation of our proposal: a logical formalization and an operational specification.