The Application of Filtration Technology Within the Water Processor on Board Space Station Freedom

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. The proposed filtration scheme throughout the entire Water Processor will contain eleven filters including a final filter sized at 0.04 micron absolute.