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Pretreatment of urine using Oxone® and sulfuric acid is baselined in the International Space Station (ISS) waste water reclamation system to control odors, fix Ammonia and control microbial growth. In addition, pretreatment is recommended for long term flight use of urine collection and two phase separation to reduce or eliminate fouling of the associated hardware and plumbing with urine precipitates. This is important to the ISS application because the amount of maintenance time for cleaning and repairing hardware must be minimized. This paper describes the development of a chemical pretreatment system based on solid tablet shapes which are positioned in the inlet urine collection hose and are dissolved by the entrained urine at the proper ratio of pretreatment to urine. Building upon the prior success of the developed and tested solid Oxone tablet, a trade study and tests were completed to confirm if a similar approach would be appropriate for the sulfuric acid injection method.

A liquid/gas separator called the Mostly Liquid Separator (MLS) has been devised to provide liquid/gas separation with soapy fluids in a microgravity environment, and is an integral component of the International Space Station Water Processor. Now in its third generation of development, this paper describes the evolution of the MLS design, and presents a discussion of the development test data and results.

Water reclamation from human urine will be the basis of the closed loop Water Recovery Management (WRM) system on Space Station Freedom (SSF). Pretreatment is necessary to collect and process urine, fix and prevent ammonia formation, inhibit microbial growth and prevent solids precipitation. Pretreatment must be accomplished immediately upon collection to prevent damage to urine collection and handling equipment. Currently, a chemical injection scheme is an integral part of the SSF Urinal design. The reagents used will be based on compatibility with Urinal and Urine Processor components, performance of necessary pretreatment functions, quality of reclaimed water, resupply costs and development risks. These factors are compared for various pretreatment methods currently under consideration for use on SSF.