Microbial Characterization of Heat Melt Compaction for Treatment of Space Generated Solid Wastes

Date

7/10/2022

Journal Title

Journal ISSN

Volume Title

Publisher

51st International Conference on Environmental Systems

Abstract

One treatment process in development for solid waste management in space has been the Trash Compaction Processing System (TCPS). Heat Melt Compaction (HMC) technology, a TCPS liked hardware, which is operated to reduce trash volume and safen the trash by compaction and heat, while simultaneously removing water. Human space mission wastes typically contain large percentages contaminated wet solid waste. The HMC is being developed to be a multi-function means of water recovery, volume reduction, and the safening of contaminant-rich trash with the potential for waste stabilization and/or sterilization. To determine the efficacy of the HMC treatment to kill microorganisms in solid waste and remain biologically stable, testing was done on three tiles produced by HMC Gen 2 at Ames Research Center. Samples were shipped to Kennedy Space Center to test for microbial viability after compaction, determine the bio-stability of the HMC disks during storage (43 days), and assess potential airborne contaminate microbial growth on surfaces. In addition to the products of waste processing, there is a concern that the crew might come into contact with hardware surfaces that have been contaminated by microorganisms during waste processing. The extent of microbial surface contamination of waste processing hardware was determined by surface sample swabbing and analysis for total bacterial and yeast counts and cultivable counts of aerobic and anaerobic bacteria, spore-forming bacteria, and fungi. Results indicate that trash processing increased bacterial counts on the surfaces of the compacter. All but one biological indicator spore strip imbedded in the tiles were negative for growth after incubation for five days indicating effective sterilization through the heat melt compaction process. Analysis of core samples and surface growth of tiles inoculated with Aspergillus niger fungal spores incubated at three different humidities indicate that HMC created tiles do not support the proliferation of bacterial and fungal growth.

Description

Mary Hummerick, Amentum Services, US
Jason Fisher, Amentum Services, US
Raymond Wheeler, NASA, US
Tra-My Justine Richardson, NASA, ARC, US
Michael Ewert, NASA, ARC, US
Jeffrey Lee, NASA, ARC, US
Lawrence Koss, Amentum Services, US
ICES304: Physio-Chemical Life Support- Waste Management Systems- Technology and Process Development
The 51st International Conference on Environmental Systems was held in Saint Paul, Minnesota, US, on 10 July 2022 through 14 July 2022.

Keywords

Solid waste, Compaction, Biostability

Citation