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A flex hose assembly containing aqueous coolant from the International Space Station (ISS) Internal Active Thermal Control System (IATCS) consisting of a 2 foot section of Teflon hose and quick disconnects (QDs) and a Special Performance Checkout Unit (SPCU) heat exchanger containing separate channels of IATCS coolant and iodinated water used to cool spacesuits and Extravehicular Mobility Units (EMUS) were returned for destructive analyses on Shuttle return to flight mission STS-114. The original aqueous IATCS coolant used in Node 1, the Laboratory Module, and the Airlock consisted of water, borate (pH buffer), phosphate (corrosion control), and silver sulfate (microbiological control) at a pH of 9.5 rt 0.5. Chemical changes occurred after on-orbit implementation including a decrease to pH 8.4 due to the diffusion of carbon dioxide through the Teflon hoses, an increase in nickel ions due to general corrosion of heat exchanger braze coatings, a decrease in phosphate concentration due to precipitation of nickel phosphate, and the rapid disappearance of silver ions due to deposition on hardware surfaces. Also associated with the coolant chemistry changes was an increase in planktonic microorganisms from less than 100 colony forming units (CFU) per 100 ml to approximately 1 million CFU per 100 ml. Attachment and growth of microorganisms to the system surfaces (biofilm) was suspected due to the levels of planktonic microorganisms in the coolant. Biofilms can reduce coolant flow, reduce heat transfer, amplify degradation of system materials initiated by chemical corrosion, and enhance mineral scale formation.Enumerations of microorganisms on hardware surfaces were performed by membrane filtration and spread plating on R2A, 1 /1 0-strength tryptic soy agar, and fluid thioglycollate medium agar incubated for 14 days at 25 -30°C.Enrichments of viable microorganisms from surfaces of the flex hose and SPCU heat exchanger were performed in R2B (R2A without agar), 1MO-strength tryptic soy broth, and fluid thioglycollate medium. Bacterial colonies isolated from these assays were isolated and identified by several methods.This initial paper reports the results of the membrane filtration analyses performed to assess biofilm on IATCS hardware exposed to coolant and microorganisms during five years of on-orbit operation.

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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

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