Updated Effluent Analysis of the Heat Melt Compactor: Water Quality and Dewpoint Simulation of Gas Effluent

The Trash Compaction and Processing System (TCPS) processes astronaut trash through volume reduction, biological safening, trash stabilization, effluent management, and resource recovery. TCPS development for the International Space Station (ISS) and risk reduction activities are supported by testing the Heat Melt Compactor (HMC) at NASA Ames Research Center (ARC). Processing trash extracts water vapor that can be recovered and releases volatile gases that must be managed. Part of the effluent is condensed and collected for analysis. The evaluation of the liquid effluent includes total organic carbon (TOC) concentrations, which provide a general indication of overall water quality, other defining characteristics such as pH and conductivity, and identified chemical components. On the other hand, the gas effluent may be recovered through a contaminant control system and vented to ISS cabin or vented overboard into space through the ISS Vacuum Exhaust System (VES). In the latter venting scenario, a constraint is the dewpoint of the gases disposed into the VES must be less than 15.5 oC. With simulations using Aspen Plus� and the HMC gas effluent results, flash calculations were conducted in the modeling study to calculate feed temperature and dewpoint at fixed pressures. Saturated vapor curves were also produced and provide a preliminary result on optimal feed conditions that satisfy the dewpoint and vapor-phase only requirements upon venting to VES. This paper serves as an update on the ongoing liquid and gas effluent analysis of the HMC/TCPS.