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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.

Space Station Freedom uses a semi-closed loop recirculating waste water system to regenerate potable water. A specific series of depth and membrane filters can be employed prior to the waste water holding tank to eliminate bacteria at the earliest portion of the Water Processor. Several advantages accrue by using a cold sterilizing method for microbial control. This methodology i) reduces the weight and power requirements needed for a heat sterilizer and exchanger, and ii) significantly reduces biocorrosion and biofilm associated problems. A series of six filters and a two component resin bed was used to process a mixture of laundry water, shower water, and urine distillate in a ratio of 63:28:9 by volume. The final effluent was free of bacteria when grown on R2A agar. Gravimetric analysis was performed on 100 ml of downstream effluent from four filters and compared to the raw water.