Hali Shaw

Brine Evaporation Bag Design Concept and Initial Test Results

The Brine Evaporation Bag (BEB) was designed for dewatering the residual brine generated from a spacecraft’s primary wastewater treatment systems. The BEB is a closed bag structure with hydrophobic membranes in its sidewalls to facilitate the dewatering of the concentrated brine that fills it. In order to provide the energy required to dewater the brine, the BEB is placed inside a heating chamber such as the Heat Melt Compactor (HMC). As the temperature of the brine increases, the water in the brine transforms to water vapor. The water vapor then leaves the brine and passes through the membrane installed in the sidewall of the BEB. The HMC provides the condensation and subsequent handling of the water produced by this process and delivers it to the primary water processor. As a result, the BEB is left with either a highly concentrated brine liquid or a solid inside the bag. The BEB process has an advantage over traditional drying techniques in that it is resistant to precipitation and scaling failure. The focus of this paper is on the initial design concepts and testing of the BEB. This includes the testing of various membrane materials: an expanded polytetrafloroethylene, two expanded polypropylene, and a reticulated polypropylene. The results of this study showed that the reticulated polypropylene was the most mechanically stable when compared to the other membrane materials. The BEB was also able to achieve 96% water recovery without fouling the membrane.

Forward Osmosis Cargo Transfer Bag

All human space missions, regardless of destination, require significant logistical mass and volume. The amount required is a function of the mission duration. Reducing this logistical mass and volume by reusing items that would otherwise become trash can reduce launch weight and consequently mission costs. This paper describes a logistics reduction technology based on repurposing International Space Station (ISS) Crew Transfer Bags (CTB). CTBs are fabric cargo containers, which conform to specific dimensional and material requirements for space flight. This paper describes the development of a Forward Osmosis Cargo Transfer Bag (FO-CTB) that can be reused on orbit to provide radiation sheading and water recycling capacity. The design, construction and testing of a prototype FO-CTB at the Desert Research and Technology Studies (D-Rats) Habitat Demonstration Unit (HDU) in 2011 is described. In addition, a summary of the results of a flight experiment performed to evaluate the effect of microgravity on the forward osmosis (FO) membrane bags used in the FO-CTB is also discussed. Future plans for the continued development of the FO-CTB are also discussed.

Osmotic Distillation for the Recycle of Spacecraft Wastewater

The osmotic distillation (OD) system is being developed as spacecraft water treatment system capable of recycling urine and humidity condensate to potable standards. This technology uses osmotic distillation followed by reverse osmosis (RO). OD is an isothermal distillation process. It uses the osmotic potential difference between a feed stream and an osmotic agent (OA) to distill water across a hydrophobic membrane. This membrane has pores small enough to allow water vapor to pass but acts as a barrier to the passage of liquid water. An RO system is used to remove the condensed water from the OA as product at the same rate that it crosses the OD membrane. The RO system also reconstitutes the OA. The OD system produces water with non-purgeable total organic carbon (NPTOCs) typically below 3 mg/l when treating human urine and produces water with TOC below 10 ppm when treating a combination of humidity condensate and urine. Total dissolved solids and ammonia are typically below NASA potable specifications. Post treatment with activated carbon or oxidation may be required to address residual odor issues in some cases. The OD system is being developed as an emergency backup to more conventional water treatment systems or as primary water treatment system for shorter missions such as early stages of a Lunar base, extended lunar rover missions, Mars transit missions, near Earth asteroid missions, or LaGrange point “Great Observatory” type missions. This paper provides results of testing of the OD system to date.

Habitat Water Wall for Water, Solids, and Atmosphere Recycle and Reuse

The membrane water wall concept proposes a system for structural elements that provide, thermal, radiation, water, solids and air treatment functions that are embedded into the walls of inflatable or rigid habitats. It provides novel and potentially game changing mass reduction and reuse, along with additional structural advantages over current mechanical life support hardware, structural materials, and radiation protection functions. The approach would allow water recycling, air treatment, thermal control, and solids residuals treatment and recycling to be removed from the usable habitat volume, and placed in the walls by way of a radiation shielding water wall. It would also provide a mechanism to recover and reuse water treatment (solids) residuals to strengthen the habitat shell. Water wall treatment elements would be a much-enlarged version of the commercially available hydration bag. Some water bags would have pervaporation membranes facing inward, which would provide the ability to remove H 2 O, CO 2 and trace organics from the atmosphere. This paper provides the results of experimental work evaluating the performance of the X-Pack TM hydration bag to treat simulated wastewater and solid wastes and determine the maximum water recover ratio that can be achieved.

Sustainability Base Graywater Recycling System

This paper describes the design history, prototyping, and predictive testing of a graywater recycling system designed for the new NASA Ames green Federal building. The goal of developing this water recycling system is to both reduce the building’s water consumption and provide a laboratory for the long duration testing of a next generation spacecraft water recycling system. The project will also demonstrate the feasibility of recycling graywater inside an office building and will help to define a permitting and monitoring process that can be applied to other sites. The Sustainability Base water recycling system has been designed to treat hygiene water and reuse it as toilet flush water. The technology is based on the integration of forward and reverse osmosis membrane systems. The system is expected to reduce water consumption in the building by about 60%. The graywater treatment system is a larger version of a technology developed by NASA for the treatment of spacecraft wastewater. Operational testing of this system in the Sustainability Base building will provide the long duration performance data which is required to evaluate the technology for future human space flight applications.

Governing Parameters of the Osmotic Distillation System: A Spacecraft Wastewater Recycling System

The osmotic distillation (OD) system is a membrane-based wastewater treatment process that can function as a water treatment system for long duration human space flight missions. This system was designed specifically to produce potable water from a mixture of human urine and humidity condensate. The process consists of two stages starting with osmotic distillation, which is followed by reverse osmosis. When treating a mixture of human urine and simulated humidity condensate, this system can produce water with a total organic carbon (TOC) concentration below 10 ppm. 4