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A microelectrode-based electrochemical detection method was used for quantitation of bacteria in water samples. The redox mediator, benzoquinone, was used to accept electrons from the bacterial metabolic pathway to create a flow of electrons by reducing the mediator. Electrochemical monitoring electrodes detected the reduced mediator as it diffused out of the cells and produced a small electrical current. By using a combination of microelectrodes and monitoring instrumentation, the cumulative current generated by a particular bacterial population could be monitored. Using commercially available components, an electrochemical detection system was assembled and tested to evaluate its potential as an emerging technology for rapid detection and quantitation of bacteria in water samples.

Electrochemical oxidant generation has been combined with UV photolysis to provide a highly effective means of water purification, decomposition of bacterial organic substances, microbiological control and sterilization. Ozone is an oxidant with many unique features that make it a valuable tool for biomedical applications. It is an excellent bactericidal, virucidal and sporicidal agent making it ideal for use as a sterilant. Combining O3 with UV radiation stimulates formation of hydroxyl radicals (OH·) which accelerates a wide range of organic oxidations. While in some instances maintenance of an oxidant residual is necessary, the residual can be rapidly removed by UV light at the point of use (i.e., Water For Injection). Test results on pyrogen decomposition, bacterial organic decomposition, microbiological sterilization, residual removal and water purification as a final step for producing pharmaceutical grade water are discussed.

The purification of reclaimed water is essential to water reclamation technology life-support systems in lunar/Mars habitats. Lynntech, Inc., working with NASA-JSC, is developing an electrochemical UV reactor which generates oxidants, operates at low temperatures and requires no chemical expendables. The reactor is the basis for an advanced oxidation process, in which electrochemically generated ozone and hydrogen peroxide are used, in combination with ultraviolet light irradiation, to produce hydroxyl radicals. Results from this process are presented which demonstrate concept feasibility for removal of organic impurities and disinfection of water for potable and hygiene reuse. Power, size requirements, Faradaic efficiency and process reaction kinetics are discussed. At the completion of this development effort, the reactor system will be installed in JSC's regenerative water recovery test facility for evaluation to compare this technique with other candidate processes.