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Heat Melt Compaction as an Effective Treatment for Eliminating Microorganisms from Solid WasteOne of the technologies being tested at Ames Research Center as part of the logistics and repurposing project is heat melt compaction (HMC) of solid waste to reduce volume, remove water and render a biologically stable and safe product. Studies at Kennedy Space Center have focused on the efficacy of the heat melt compaction process for killing microorganisms in waste and specific compacter operation protocols, i.e., time and temperature required to achieve a sterile, stable product. The work. reported here includes a controlled study to examine the survival and potential re-growth of specific microorganisms over a 6-month period of storage after heating and compaction. Before heating and compaction, ersatz solid wastes were inoculated with Bacillus amyloliquefaciens and Rhodotorula mucilaginosa, previously isolated from recovered space shuttle mission food and packaging waste. Compacted HMC tiles were sampled for microbiological analysis at time points between 0 and 180 days of storage in a controlled environment chamber. In addition, biological indicator strips containing spores of Bacillus atrophaeus and Geobacillus stearothermophilus were imbedded in trash to assess the efficacy of the HMC process to achieve sterilization. Analysis of several tiles compacted at 180deg C for times of 40 minutes to over 2 hours detected organisms in all tile samples with the exception of one exposed to 180deg C for approximately 2 hours. Neither of the inoculated organisms was recovered, and the biological indicator strips were negative for growth in all tiles indicating at least local sterilization of tile areas. The findings suggest that minimum time/temperature combination is required for complete sterilization. Microbial analysis of tiles processed at lower temperatures from 130deg C-150deg C at varying times will be discussed, as well as analysis of the bacteria and fungi present on the compactor hardware as a result of exposure to the waste and the surrounding environment. The two organisms inoculated into the waste were among those isolated and identified from the HMC surfaces indicating the possibility of cross contamination.
Document ID
20130013700
Acquisition Source
Kennedy Space Center
Document Type
Conference Paper
Authors
Hummerick, Mary P. (QinetiQ North America Kennedy Space Center, FL, United States)
Strayer, Richard F. (QinetiQ North America Kennedy Space Center, FL, United States)
McCoy, Lashelle E. (QinetiQ North America Kennedy Space Center, FL, United States)
Richards, Jeffrey T. (QinetiQ North America Kennedy Space Center, FL, United States)
Ruby, Anna Maria (NASA Kennedy Space Center Cocoa Beach, FL, United States)
Wheeler, Ray (NASA Kennedy Space Center Cocoa Beach, FL, United States)
Fisher, John (NASA Ames Research Center Moffett Field, CA, United States)
Date Acquired
August 27, 2013
Publication Date
January 1, 2013
Subject Category
Man/System Technology And Life Support
Report/Patent Number
KSC-2013-083R
KSC-2012-313
Meeting Information
Meeting: 43rd International Conference on Environmental Systems
Location: Vail, CO
Country: United States
Start Date: July 14, 2013
End Date: July 18, 2013
Sponsors: American Inst. of Aeronautics and Astronautics
Funding Number(s)
CONTRACT_GRANT: NNK11EA08C
Distribution Limits
Public
Copyright
Public Use Permitted.

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