Search Results

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.

Environmental Control and Life Support Systems (ECLSS) of Space Station Freedom are closed loop recirculating systems. Major subsystems of ECLSS (Air, Water, and Temperature and Humidity Control) will require particulate and microbial control. Elimination or reduction of these contaminants can be achieved through the appropriate placement of microbially retentive filters. Current technologies allow particulate removal from gases to 0.01 micron which eliminates all known viruses. Filtration of liquids can remove all particles to 0.04 micron which eliminates all known bacteria, fungi, and many viruses. In addition, sterilizing grade membrane filters can be periodically nondestructively in-situ tested to monitor integrity during service. This paper reviews state of the art technologies of gas and liquid filtration utilized in the semiconductor, pharmaceutical, health care, and food/beverage industries and how similar advanced filtration technology can be adapted for Space Station Freedom.