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In a harmonized ESA/NIVR project the performance of membrane gas absorption for the simultaneous removal of carbon dioxide and moisture has been determined experimentally at carbon dioxide and humidity concentration levels representative for spacecraft conditions. Performance data at several experimental conditions have been collected. Removal of moisture can be controlled by the temperature of the absorption liquid. Removal of carbon dioxide is slightly affected by the temperature of the absorption liquid. Based on these measurements a conceptual design for a carbon dioxide and humidity control system for the Crew Transport Vehicle (CTV) is made. For the regeneration step in this design a number of assumptions have been made. The multifunctionality of membrane gas absorption makes it possible to combine a number of functions in one compact system.

A mathematical model has been developed in order to support the design, engineering and testing of a membrane based biological air filter, removing and converting gas phase contaminants present within a closed environment, like manned space habitats, before they reach toxic concentrations. The configuration of the system is described by a gas phase, containing the contaminants, and a liquid phase, separated by membrane material, supporting a film of selected innocuous microorganisms in a near resting state, catabolizing the contaminants to inert materials, mainly carbon dioxide, water and salts. The process simulation and its results are discussed, considering the different diffusion and biochemical processes taking place inside the biological system.

A biological airfilter (BAF) is designed for the recycling of cabin air in crewed spacecraft. A literature study was conducted to select an appropriate method for the detection, identification, and enumeration of autochtonous bacterial strains and possible (pathogenic) infections in the air filter. The most suitable technique appears to be the use of fluorescently labeled 16S rRNA probes. The DNA labels can selectively bind to intact bacterial cells, thus enabling a quantitative detection with flow cytometry or fluorescence microscopy. Detection of possible infections can be performed with 16S rRNA probes or with PCR detection kits for a more sensitive detection.