Browse Publications Technical Papers 2003-01-2568

Selection of an Alternate Biocide for the International Space Station Internal Active Thermal Control System Coolant Loops 2003-01-2568

The International Space Station (ISS) IATCS (Internal Active Thermal Control System) includes two internal coolant loops that use an aqueous based coolant for heat transfer. A silver salt biocide was used initially as an additive in the coolant formulation to control the growth and proliferation of microorganisms in the coolant loops. Ground-based and in-flight testing has demonstrated that the silver salt is rapidly depleted and not effective as a long-term biocide. Efforts are now underway to select an alternate biocide for the IATCS coolant loop with greatly improved performance.
An extensive evaluation of biocides was conducted to select several candidates for test trials. Selection criteria included: the need for safe, non-intrusive implementation and operation in a functioning system; the ability to control existing planktonic and biofilm residing microorganisms; a negligible impact on system-wetted materials of construction; and a negligible reactivity with existing coolant additives.
Candidate testing is underway to provide data to select an optimal alternate biocide. That testing includes rapid biocide effectiveness screening using Biolog MT2 plates, minimum inhibitory concentration determination defined as the amount of test substance that will inhibit growth of microorganisms, materials compatibility evaluations, and coolant compatibility studies. In parallel with this effort, methods to introduce and maintain effective system biocide concentrations in-flight are being investigated.
This effort will result in the selection of an optimal alternate biocide and delivery method that will subsequently undergo ground verification testing before implementation.
This paper reports the current status of the effort to select an alternate biocide for the ISS IATCS coolant loops. The evaluation that was conducted to select candidates for test trials is presented.


Subscribers can view annotate, and download all of SAE's content. Learn More »


Members save up to 17% off list price.
Login to see discount.
Special Offer: Download multiple Technical Papers each year? TechSelect is a cost-effective subscription option to select and download 12-100 full-text Technical Papers per year. Find more information here.
We also recommend:

Development of Waste Bag Air Flow and Drying Models for Solid Waste Management


View Details


Lyophilization for Water Recovery II, Model Validation


View Details


Selection of an Alternate Biocide for the ISS Internal Thermal Control System Coolant - Phase II


View Details