Abstract
CELSS (Controlled Ecological Life Support Systems) is to be considered to construct the closed environment for sustaining the life including human beings without any material supply from outside. The water recycling system is a key subsystem of the integrated material recycling system which must be developed to obtain long-term, manned space activity. This paper presents the results of system study for designing water recycling system in which three kinds of membrane filters (UF, RO and TPV) are introduced to purify waste water discharged from men, animals and plants. In addition, the long duration processing tests utilizing artificial urine waste water were conducted to evaluate the appropriateness to adapt these membrane filters.
The following results were obtained: 1) The prototype water recycling system could be controlled and working smoothly. However, the system needed some maintenance of several parts of the equipments for it to operate completely in the given desired period. 2) The removable rate of water from artificial urine was below 60%. 3) The crystal materials namely MgKPO4⋅6H2O, Mg3 (PO4) 2⋅4H2O and CaHPO4⋅2H2O which shortened the life time of each filter were found in tank, pipe and filter. 4) The urine removable rate of RO filter was lower than that of commercially sold filters which extracted only NaCl water. In the special case of ammonia which could not be extracted completely even using TPV filter after RO system, it is necessary to develop a new filter that can remove ammonia for a further suitable process.
