Updated Performance Evaluation of the ISS Water Processor Multifiltration Beds

Abstract

The ISS Water Processor Assembly (WPA) produces potable water from a waste stream containing humidity condensate and urine distillate. The primary treatment process is achieved in the Multifiltration Beds, which include adsorbent media and ion exchange resin for the removal of dissolved organic and inorganic contaminants. Two Multifiltration Beds (MF Beds) were replaced on ISS in July 2010 after initial indication of inorganic breakthrough of the first bed and an increasing Total Organic Carbon (TOC) trend in the product water. The first bed was sampled and analyzed Sept 2011 through March 2012. The second MF Bed was sampled and analyzed June 2012 through August 2012. The water resident in the both beds was analyzed for various parameters to evaluate adsorbent loading, performance of the ion exchange resin, microbial activity, and generation of leachates from the ion exchange resin. Portions of the adsorbent media and ion exchange resin were sampled and subsequently desorbed to identify the primary contaminants removed at various points in the bed in addition to microbial analysis. Analysis of the second bed will be compared to results from the first bed to provide a comprehensive overview of how the Multifiltration Beds function on orbit. New data from the second bed supplements the analysis of the first bed (previously reported) and gives a more complete picture of breakthrough compounds, resin breakdown products, microbial activity, and Tube 1 -Adsorbent Water -2.2E+07 CFU/100 mL; Resin -2.24E+04 CFU/g Tube 2 -Adsorbent Water 2.6E+06 CFU/100 mL; Resin -2.56E+03 CFU/g Tube 3 -Adsorbent Water -2.0E+07 CFU/100 mL; Resin -1.15E+04 CFU/g Tube 4 -Mixed Ion Exchange Resin Water -7.4E+03 CFU/100 mL; Resin -2.02E+03 CFU/g Tube 5 -Mixed Ion Exchange Resin Water -3.7E+07 CFU/100 mL; Resin -3.54E+02 CFU/g Tube 6 -Mixed Ion Exchange Resin Water -4.9E+07 CFU/100 mL; Resin -2.27E+02 CFU/g Tube 7 -Mixed Ion Exchange Resin Water -8.3E+05 CFU/100 mL; Resin -<2 CFU/g Tube 8 -Mixed Ion Exchange Resin Water -<1 CFU/100mL; Resin -<2 CFU/g Tube 9 Weak-Base Anion Exchange Resin Resin -<2 CFU/g Tube 10 -Mixed Ion Exchange Resin Water 9.3E+02 CFU/100 mL; Resin 3.97E+02 CFU/g Tube 9-Strong-Acid Cation Exchange Resin Resin -6 CFU/g Water -3.3E+05 CFU/100 mL; Resin -3.00E+04 CFU/g Tube 2 -Adsorbent Water <10 CFU/100 mL; Resin -1.01E+05 CFU/g Tube 3 -Adsorbent Water -1.9E+06 CFU/100 mL; Resin -2.00E+04 CFU/g Tube 4 -Mixed Ion Exchange Resin Water -7.4E+03 CFU/100 mL; Resin -1.53E+02 CFU/g Tube 5 -Mixed Ion Exchange Resin Water -3.2E+04 CFU/100 mL; Resin -49 CFU/g Tube 6 -Mixed Ion Exchange Resin Water -3.9E+05 CFU/100 mL; Resin -2.42E+02 CFU/g Tube 7 -Mixed Ion Exchange Resin Water -2.0E+04 CFU/100 mL; Resin -2.03E+06 CFU/g Tube 8 -Mixed Ion Exchange Resin Water -<10 CFU/100mL; Resin -1.84E+03 CFU/g Tube 9 Weak-Base Anion Exchange Resin Resin -1.33E+03 CFU/g

Status of ISS Water Management and Recovery

“…A detailed review of this investigation and results can be found elsewhere 7 . However, a key finding was that several polydimethylsiloxanes (PDMS) had saturated the adsorbent and ion exchange resin.…”