Assessment of Silver Based Disinfection Technology for CEV and Future US Spacecraft: Microbial Efficacy

Roberts, Michael S.; Hummerick, Mary E.; Edney, Sharon L.; Bisbee, Patricia; Callahan, Michael R.; Loucks, Sandy; Pickering, Karen D.; Sager, John C.

doi:10.4271/2007-01-3142

Cited by 5 publications

(4 citation statements)

References 4 publications

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“…After that, the observed Ag reduction continues only gradually even after several months of exposure. Likewise, Roberts et al [15] observed a considerable silver reduction, higher than 10% of the initial silver concentration, when SS316L solid surfaces were exposed to water containing 0.5 mg/L Ag at a ratio of S/V equal to 0.14 cm −1 . In this study, the overall reduction of Ag is calculated around 70% Figure 2b presents the evolution of Ag concentration in the bulk potable water with respect to exposure time under nitrogen headspace and S/V ratio equal to 0.1 cm −1 .…”

Section: Experimental Kinetic Datamentioning

confidence: 83%

Longevity Aspects of Potable Water Disinfected by Ionic Silver: Kinetic Experiments and Modeling

Petala

Tsiridis

Darakas

et al. 2020

Water

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In the International Space Station (ISS), Russian and European cosmonauts drink water disinfected by dissolved silver. For this to be effective, the concentration of silver should remain above a certain threshold from the moment of its initial disposition in storage tanks on earth until its final consumption in ISS. Unfortunately, during water tanks transportation to ISS and during storage in ISS, silver concentration has been reported to decrease intensively beyond any reason. This work examines the effect of different materials used in ISS water storage and distribution systems on the reduction of silver concentration. An experimental campaign has been organized where passivated stainless steel (SS), passivated and electropolished SS and titanium alloy coupons (official ISS grades) are exposed to simulated ISS potable water at different silver concentrations, different surface to volume ratios, and at stagnant or flow conditions. The evolution of silver concentration remaining in the bulk water is recorded with respect to the exposure time. A reaction engineering model for the Ag loss to the coupons is developed. The model is fitted to the experimental data in order to derive the reaction rate expression and the corresponding parameters. For passivated SS and electropolished SS the silver deposition rate depends on the initial silver concentration in water but is rather unaffected by the progress of silver deposition on the surface. On the other hand, for Ti alloy, while silver deposition rate still depends on initial silver concentration, it decreases continuously as silver deposition on the surface advances, implying that Ti alloy surface becomes gradually saturated and so prevents further silver deposition. Such a model can be useful for material selection and design of water storage and distribution facilities for ISS.

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Section: Experimental Kinetic Datamentioning

confidence: 83%

Longevity Aspects of Potable Water Disinfected by Ionic Silver: Kinetic Experiments and Modeling

Petala

Tsiridis

Darakas

et al. 2020

Water

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“…The human body excretes 90% of silver ions when ingested at low concentrations (i.e., 500 ppb). [9][10][11] If future space missions adopt a semi-continuous WRS and silver as a biocide, a passive biocide dosing system (PBDS) will be an indispensable WRS component. Thus, addressing the technical necessities in designing an efficient WRS for spacecraft or extraterrestrial bases, a unique design for a PBDS has been formulated by exploring the capabilities of dialysis as biocide dosing mechanisms.…”

Section: Introductionmentioning

confidence: 99%

Dialysis-based Passive Biocide Delivery System: An Exploratory Analysis on the Development of a Silver Dosing Alternative for Spacecraft Potable Water Systems

Garcia Fernandez

2024

Preprint

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This paper describes the use of a dialysis-based passive dosing system for silver ion delivery as a biocide for potable water systems in spacecraft and extraterrestrial bases. A silver dosing device has been developed for continuous water treatment, based on the International Space Station Water Processor Assembly framework. The Passive Biocide Delivery System is designed to supply a stream of product water with silver ions at a concentration range of 200-400 ppb, using a membrane to control dosing. Potable water with these silver concentrations can be safely consumed by humans. The dialysis approach is attractive since it does not require additional energy nor high pressure to function. Computational Transport Phenomena has been implemented to study the performance of the membrane setup at particular operational conditions and guide the choice of membrane properties. The results suggest that the dosing device can release silver ions at the target levels for at least eight hours without excessive silver salt consumption. This paper contains technical background and preliminary results from the Passive Biocide Delivery System development and presents the benefits and challenges of its implementations in spacecraft and Lunar/Martian bases.

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“…The refilled hose was left at room temperature for over 1 month before launch. Silver (ionic and colloidal) and iodine are commonly used to disinfect potable water systems onboard the ISS and Space Shuttles (Koenig et al 1995;Roberts et al 2007). After failing the ISS specifications, an in-flight treatment of the PWD ambient leg with 40 ppm iodine was attempted, but was not successful in reducing the bacterial concentration.…”

Section: Introductionmentioning

confidence: 99%

Efficacy of various chemical disinfectants on biofilms formed in spacecraft potable water system components

Wong¹,

Dudinsky²,

García³

et al. 2010

Biofouling

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Wong, Wing C.; Dudinsky, Lynn A.; Garcia, Veronica M.; Ott, Charlie M.; and Castro, Victoria A., "Efficacy of various chemical disinfectants on biofilms formed in spacecraft potable water system components" (2010 As the provision of potable water is critical for successful habitation of the International Space Station (ISS), life support systems were installed in December 2008 to recycle both humidity from the atmosphere and urine to conserve available water in the Station. In-flight pre-consumption testing from the dispensing needle at the Potable Water Dispenser (PWD) indicated that bacterial concentrations exceeded the current ISS specifications of 50 colony-forming units (CFU) ml 71. Subsequent investigations revealed that a corrugated stainless steel flex hose upstream of the dispensing needle in the PWD was filled with nonsterile water and left at room temperature for more than 1 month before launch. To simulate biofilm formation that was suspected in the flight system, sterile flex hoses were seeded with a consortium of bacterial isolates previously recovered from other ISS water systems, including Ralstonia pickettii, Burkholderia multivorans, Caulobacter vibrioides, and Cupriavidus pauculus. After incubation for 5 days, the hoses were challenged with various chemical disinfectants including hydrogen peroxide (H 2 O 2 ), colloidal silver, and buffered pH solutions to determine the ability of the disinfectants to decrease and maintain bacterial concentrations below ISS specifications. The disinfection efficacy over time was measured by collecting daily heterotrophic plate counts after exposure to the disinfectants. A single flush with either 6% H 2 O 2 solution or a mixture of 3% H 2 O 2 and 400 ppb colloidal silver effectively reduced the bacterial concentrations to 51 CFU ml 71 for a period of up to 3 months.

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Assessment of Silver Based Disinfection Technology for CEV and Future US Spacecraft: Microbial Efficacy

Cited by 5 publications

References 4 publications

Longevity Aspects of Potable Water Disinfected by Ionic Silver: Kinetic Experiments and Modeling

Longevity Aspects of Potable Water Disinfected by Ionic Silver: Kinetic Experiments and Modeling

Dialysis-based Passive Biocide Delivery System: An Exploratory Analysis on the Development of a Silver Dosing Alternative for Spacecraft Potable Water Systems

Efficacy of various chemical disinfectants on biofilms formed in spacecraft potable water system components

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