Controlling microbial growth in regenerative life support systems for closed environment in space is necessary to protect the health of the crew. The microbial control is one of key technologies of water recycling system for closed environment. The study of water recycle system for closed environment is being continued steadily also in our laboratory.
In this paper, the author carried out the experimental study as follows: (1) In order to provide the burden of microbe in waste water model, experiments holding rodents in closed environment for a month were performed. (2) Ozone disinfection was chosen as the subject of the study to evaluate applicability of use for water recycle system for closed environment, then microbe ozone sensitivity tests were performed.
The result, microbial species from experiment system include heterotrophs isolated from water and soil was obtained. Then, basic properties of ozone disinfection to accommodate water recycle system for closed environment were obtained.

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The paper have discussions on the effective elimination techniques of trace contaminants for CELSS.
The elimination of the trace contaminants produced inevitably from activities of plants and animals including a human being, and causing physiological symptoms is a matter of importance in order to sustain safe and comfortable controlled ecological environments. The result of s tudy on utilized elimination methods for the trace contaminants concludes that an application of catalyst filters with low pressure drop property to CELSS is a promissing elemental method.
Experiments on manufactured catalyst and activated carbon filters with a sectional honeycomb structure were carried out regarding specific surface area, benzene adsorption capacity, pressure drop, mechanical strength and an elimination performance for typical trace contaminants, such as, hydrogen sulfide, methyl mercaptan, ammonia, and trimethyl amine. Results of the experiments showed following conclusions.
(1) The sectional honeycomb structure was effective on a reduction in operational energy consumption, and a securement of wide surface area and required mechanical strength.
(2) Catalytst ingredients of the filter made a contribution toward higher elimination performance for the contaminants than an activated carbon, in spite of its less physical adsorption capacity.
The conclusions revealed the effect of the catalyst filters on an overall improvement of CELSS.

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The logarithmic gains, defined as a response of any dependent variable to a change in one independent variable in a steady state ofthe system, can be used to estimate the degree of stability of any closed ecological life support system (CELSS). However, understanding of its physical meaning is not sufficient. For this reason, therefore, dynamic simulation is carried out using the first-order kinetic model for the water circulation system of the plantation module in Biosphere-J. The calculated result shows that the logarithmic gain with respect to the amount of water has a close relationship with the dynamic behaviors of incoming and outgoing fluxes for a given tank and the meaning of the magnitude of its value must always be considered together with that of the logarithmic gain with respect to the flux when evaluating the performance of the system.

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Microalgae are a promising organism for bioregenerative gas revitalization, because of their high efficiency of light energy utilization and flexibility for fluctuation of CO₂ load.
Comparison of species of microalgae and effects of culture conditions on proliferation were studied to determine conditions for photo-bioreactor experiment. Germ-free strains of Spirulina platensis were chosen as promising candidates on the ground of proliferation rate, biomass composition and less possibility of interference of contaminated bacteria. Although the SOT medium resulted generally in sufficient proliferation rate and biomass concentration, proper concentration of sodium bicarbonate varied depending on luminous intensity.

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A performance characteristic of a small-sized microalgal CO₂/O₂ exchange system for the microgravity environment was investigated. The system consisted of a photosynthetic reactor with available capacity of 1.5 liter, a membrane module for gas recovery and a circulatory pump. Gas exchange experiment were carried out on Spirulina platensis with SOT medium. Oxygen generation rate per cell became maximum in the middle or latter of exponential growth phase. Oxygen generation rate per medium increase as cell concentration increased. The high irradiation intensity brought about the high cell growth rate and oxygen generation rate.

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Food and agricultural products are suggested from both farmers and consumers to select suitable plant caltivar which adapt high quantity and quality, and so it is required the system of high quality plant production. In this paper, we researched the effects of light spectral characteristics, especially the wavelength range of ultraviolet rays, on the growth and nutrient accumulation of leaf plant “Komatsuna”.
We cultivated the komatsuna by using different films in the greenhouse, which had ultraviolet rays (UV) enhanced and unenhanced. It was measured L-ascorbic acid (AsA), chlorophylla, chlorophyll-b, β-carotene, fresh weight and leaf length in komatsuna. As the results, it was found that the growth of plant decreased, but that ascorbic acid contents increased by UV rays enhanced. Komatsuna had higher ascorbic acid contents in young leaf and at winter season. Also, hydroculture induced higher accumuration of ascorbic acid contents than soil culture. But chlorophyll-a, chlorophyll-b and β-carotene contents did not change by that rays.

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