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Materials circulating in a closed ecological system are classified as metabolic ones and nonmetabolic ones. Nonmetabolic substances relate to environment constituents and cultural activities. Treatment of these materials are discussed from a view point of CELSS concept. The closed system, CEEF, will be constructed in Japan in the near future. CEEF is an experiment facility with processing capacity of two adult persons, consisting of a plant module, an animal module, a habitat module and supporting facilities for the three modules. The supporting facilities are composed of artificial processors of gases, waters and wastes. The plant module has artificial and natural lighting cultivating sections.

We propose a new recovery system for NaCl from human urine. The system has an electrodialysis (ED) part and a crystallization part. Separation and concentration characteristics of the system are discussed for fundamental experiments of the ED and crystallization parts. Concentrated NaCl-KCl mixed solution is obtained using the ED process from simulated oxidized urine and sweat which include Ca2+ and S042- ions. Then, the crystallization process is used to separate about 80% of the NaCl from the ED treated solution. The experimental studies indicate that the mineral recovery system we proposed can recover NaCl from waste water of a CEEF.

A unique recovery system for NaCI (salt) from urine, which consists of electrodialysis (ED) and crystallization processes is proposed. The possibility of the mineral recovery included in urine is shown in a previous report. To improve the purity of the produced salt, pH control is needed as a pretreatment. By controlling pH of the feed solution to about 10, multivalent ions such as Ca2+ and Mg2+ are crystallized as phosphate solids which can be separated by filtration. As well as raising the NaCI purity, this controls scaling b y multivalent ions.

The Nitrogen Fixation System (NFS) which produces ammonia and nitric acid from nitrogen and water has been developed. The NFS is one essential part of material circulation system of the CEEF (Closed Ecological Experiment Facility) the first Japanese CELSS experiment facility. Basically, physico-chemical and some new technologies are utilized as elemental processes in the NFS. Low pressure ammonia synthesis, ammonia enrichment with PSA and water electrolysis with SPE are such new technologies. We designed and installed the NFS as a subsystem of CEEF. The capacity of the NFS is 125g/day as fixed nitrogen. First operation of NFS is expected to be done early fiscal year of 1996 in CEEF.