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At least 55 records · Page 3

Coiled Brine Recovery Assembly (CoBRA): A New Approach to Recovering Water from Wastewater Brines

Brine water recovery represents a current technology gap in water recycling for human spaceflight. The role of a brine processor is to take the concentrated discharge from a primary wastewater processor, called brine, and recover most of the remaining water from it. The current state‐of‐the‐art primary processor is the ISS Urine Processor Assembly (UPA) that currently achieves 70% water recovery. Recent advancements in chemical pretreatments are expected to increase this to 85% in the near future. This is a welcome improvement, yet is still not high enough for deep space transit. Mission architecture studies indicate that at least 95% is necessary for a Mars mission, as an example. Brine water recovery is the technology that bridges the gap between 85% and 95%, and moves life support systems one step closer to full closure of the water loop. Several brine water recovery systems have been proposed for human spaceflight, most of them focused on solving two major problems: operation in a weightless environment, and management and containment of brine residual. Brine residual is the leftover byproduct of the brine recovery process, and is often a viscous, sticky paste, laden with crystallized solid particles. Due to the chemical pretreatments added to wastewater prior to distillation in a primary processor, these residuals are typically toxic, which further complicates matters. Isolation of crewmembers from these hazardous materials is paramount. The Coiled Brine Recovery Assembly (CoBRA) is a recently developed concept from the Johnson Space Center that offers solutions to these challenges. CoBRA is centered on a softgoods evaporator that enables a passive fill with brine, and regeneration by discharging liquid brine residual to a collection bag. This evaporator is meant to be lightweight, which allows it to be discarded along with the accumulated brine solids contained within it. This paper discusses design and development of a first CoBRA prototype, and reports initial test results.

Pensinger, Stuart J.↗

Development of Low-Toxicity Wastewater Stabilization for Spacecraft Water Recovery Systems

Wastewater stabilization was an essential component of the spacecraft water cycle. The purpose of stabilizing wastewater was two-fold. First, stabilization prevents the breakdown of urea into ammonia, a toxic gas at high concentrations. Second, it prevents the growth of microorganisms, thereby mitigating hardware and water quality issues due to due biofilm and planktonic growth. Current stabilization techniques involve oxidizers and strong acids (pH=2) such as chromic and sulfuric acid, which are highly toxic and pose a risk to crew health. The purpose of this effort was to explore less toxic stabilization techniques, such as food-grade and commercial care preservatives. Additionally, certain preservatives were tested in the presence of a low-toxicity organic acid. Triplicate 300-milliliter volumes of urine were dosed with a predetermined quantity of stabilizer and stored for two weeks. During that time, pH, total organic carbon (TOC), ammonia, and turbidity were monitored. Those preservatives that showed the lowest visible microbial growth and stable pH were further tested in a six-month stability study. The results of the six-month study are also included in this paper.

Mitchell, Julie L.↗

A Comparative Analysis of Phase-Change Wastewater Processing Approaches for Microgravity

Two phase-change wastewater processing candidates, the ISS Vapor Compression Distillation (VCD) System and the Cascade Distiller System (CDS), are compared based on dynamic modeling of both technologies. Differences in fluid handling and energy recovery for the technologies are described and contrasted. Model predictions are presented showing how temperatures, pressures, and compositions vary locally within each distiller. These dynamic variations are difficult to observe experimentally and have implications regarding non-condensable buildup and salt precipitation potential. Alternative architectures involving VCD and CDS components are analyzed in terms of predicted performance and equivalent system mass (ESM). The addition of a downstream brine processor to increase water recovery is also evaluated. Options for reducing overall ESM are discussed, including the possibility of developing a single precipitation-tolerant primary wastewater processor.

Lange, Kevin↗

Wastewater Brine Purification and Recovery through Electrodialysis Ion Exchange

Reutilizing resources onboard the International Space Station (ISS) and for future deep space missions are critical for mission longevity and sustainability. Wastewater brine produced from water recovery systems contain chemical species that could be processed into a potential fertilizer for future plant systems. This can be achieved through a process called electrodialysis ion exchange. Wastewater containing inorganic salt components are fed through a series of ion exchange membranes to produce fertilizer (a phosphate rich stream), electrolysis-grade water, and other useful commodities. Electrodialysis cells consisting of anion and cation exchange membranes, monovalent anion exchange membranes, and bipolar membranes were utilized to achieve selective ion exchange. The use of the electrodialysis cells were effective for both water extraction and ion separation. Ions successfully diffused across their respective membranes into the concentrate, acid, and base streams. This resulted in pure water, a phosphate rich stream, and a separate anion/hydrogen and cation/hydroxide stream. However, sulfate and some phosphate ions were able to diffuse through the monovalent anion exchange membrane into the acid stream. This resulted in predominantly phosphate ions remaining in the concentrate. Optimization of the process was accomplished by altering flowrates of each stream and initial volumes, adjusting the power input and resulting current through each cell, and varying the starting parameters by splitting the inorganic waste input into the diluate and the concentrate. As expected, increasing the flowrate and the power input to each cell reduced the overall time of the process. However, mission constraints may require a longer duration process in order to reduce the power consumption. Further analysis will be required to determine the power input necessary to achieve ion diffusion effectively and in a timely manner.

Ion Exchange Membranes↗

The membrane bioreactor (MBR): A hybrid technology for bioregenerative wastewater treatment and resource recovery in space

Extraplanetary surface habitat life support systems (LSS) on the Moon and Mars, as well as long-duration space travel, will require novel capabilities to withstand anticipated unique, harsh conditions. In order to provide safe, habitable environments for the crew, water purification and waste processing systems will be required to treat all sources of water (condensate, Sabatier, urine, hygiene, fecal, food waste) in order to achieve the necessary levels of recovery needed to sustain life over the long-duration missions. The ability to recycle organic wastes creates an opportunity to recover critical elements (e.g., C, H, O, N, P) for subsequent food production, water purification, and atmospheric regeneration. Bioregenerative systems mimic functions of nature in engineered systems, or bioreactors, utilizing combination of prokaryotes, eukaryotes and archaea. While these systems are commonly used on Earth for wastewater treatment, bioreactors for space travel face additional challenges. Terrestrial bioreactors often rely on gravitational settling of dense flocs and granules for cell retention. For micro- or partial-gravity environments, density differential alone will not be adequate for cell retention; a gravity-independent means for cell retention is crucial. The membrane bioreactor represents the state of the art in wastewater treatment. This hybrid system combines biological processes with membrane filtration to achieve performance beyond what each can accomplish individually. The complete cell retention in an MBR allows for the decoupling of hydraulic retention time (HRT) and solids retention time (SRT), which result in a high-thruput, compact, treatment system. The Bioregenerative Water Technology Team at NASA Kennedy Space Center and the University of South Florida has developed a bioregenerative platform based on the hybrid MBR technology. The overall architecture is compact, modular, flexible, and adaptable to mission evolutions. The main subsystems of the bioregenerative architecture include: 1) Anaerobic membrane bioreactor (AnMBR): Also termed the Organic processor assembly (OPA), the function of the AnMBR is to treat organic wastes such as fecal and food wastes. These wastes are characterized by a concentration of suspended solids comprised of carbohydrates, proteins and lipids. The assigned function of the AnMBR is to break down and covert suspended solids to biogas (methane, hydrogen and carbon dioxide), reduce effluent chemical oxygen demand (COD), liberate organically-bound nutrients, and remove pathogenic organisms. 2) Phototrophic membrane bioreactor (PMBR): The PMBR is comprised of a co-culture of microalgae and bacteria. The assigned function of the PMBR is to polish the permeate of the AnMBR to further remove dissolved organic carbon, manage nutrients (nitrogen transformation, load dampening), and perform air revitalization. 3) Food processor assembly (FPA): The FPA is a food production platform (prokaryotic or eukaryotic), fueled by outputs from the AnMBR, or PMBR. For the presentation, we will describe each step of the bioregenerative architecture, and present performance data from extended trials treating analog and real metabolic wastes.

Bioreactor↗

Dormancy and Recovery Testing for Biological Wastewater Processors

Resource recovery and recycling waste streams to usable water via biological water processors is a plausible component of an integrated water purification system. Biological processing as a pretreatment can reduce the load of organic carbon and nitrogen compounds entering physiochemical systems downstream. Aerated hollow fiber membrane bioreactors, have been proposed and studied for a number of years as an approach for treating wastewater streams for space exploration.

Dormancy↗

Dormancy and Recovery Testing for Biological Wastewater Processors

Bioreactors, such as aerated membrane type bioreactors have been proposed and studied for a number of years as an alternate approach for treating wastewater streams for space exploration. Several challenges remain before these types of bioreactors can be used in space settings, including transporting the bioreactors with their microbial communities to space, whether that be the International Space Station or beyond, or procedures for safing the systems and placing them into dormant state for later start-up. Little information is available on such operations as it is not common practice for terrestrial systems. This study explored several dormancy processes for established bioreactors to determine optimal storage and recovery conditions. Procedures focused on complete isolation of the microbial communities from an operational standpoint and observing the effects of: 1) storage temperature, and 2) storage with or without the reactor bulk fluid. The first consideration was tested from a microbial integrity and power consumption standpoint; both room temperature (25 C) and cold (4 C) storage conditions were studied. The second consideration was explored; again, for microbial integrity as well as plausible real-world scenarios of how terrestrially established bioreactors would be transported to microgravity and stored for periods of time between operations. Biofilms were stored without the reactor bulk fluid to simulate transport of established biofilms into microgravity, while biofilms stored with the reactor bulk fluid simulated the most simplistic storage condition to implement operations for extended periods of nonuse. Dormancy condition did not have an influence on recovery in initial studies with immature biofilms (48 days old), however, a lengthy recovery time was required (20+ days). Bioreactors with fully established biofilms (13 months) were able to recover from a 7-month dormancy period to steady state operation within 4 days (approximately 1 residence cycle). Results indicate a need for future testing on biofilm age and health and further exploration of dormancy length.

Dormancy↗

Dormancy and Recovery Testing for Biological Wastewater Processors

Bioreactors, such as the aerated hollow fiber membrane type, have been proposed and studied for a number of years as an alternate approach for treating wastewater streams for space exploration. Several challenges remain to be resolved before these types of bioreactors can be used in space settings, including transporting the bioreactors with intact and active biofilms, whether that be to the International Space Station or beyond, or procedures for safing the systems and placing them into a dormant state for later start-up. Little information is available on such operations as it is not common practice for terrestrial systems. This study explored several dormancy processes for established bioreactors to determine optimal storage and recovery conditions. Procedures focused on complete isolation of the microbial communities from an operational standpoint and observing the effects of: 1) storage temperature, and 2) storage with or without the reactor bulk fluid. The first consideration was tested from a microbial integrity and power consumption standpoint; both ambient temperature (25 C) and cold (4 C) storage conditions were studied. The second consideration was explored; again, for microbial integrity as well as plausible real-world scenarios of how terrestrially established bioreactors would be transported to microgravity and stored for periods of time between operations. Biofilms were stored without the reactor bulk fluid to simulate transport of established biofilms into microgravity, while biofilms stored with the reactor bulk fluid simulated the most simplistic storage condition to implement operations for extended periods of nonuse. Dormancy condition did not have an influence on recovery in initial studies with immature biofilms (48 days old), however a lengthy recovery time was required (20+ days). Bioreactors with fully established biofilms (13 months) were able to recover from a 7-month dormancy period to steady state operation within 4 days (approx. 1 residence cycle). Results indicate a need for future testing on biofilm age and health and further exploration of dormancy length.

Recovery Testing↗

Feasibility demonstration of a hyperfiltration technique to reclaim shower wastewater at elevated temperatures

A feasibility demonstration of a hyperfiltration technique to determine its capability to reclaim shower wastewater at elevated temperature was conducted. Approximately twenty (20) gallons of typical shower water were processed through a dynamically formed membrane at a temperature of 167 F. Chemical and bacterial analyses of the product water are presented which show compliance with all potable water requirements established for extended manned space missions. In addition, subsystem characteristics and capabilities are discussed.

Hester, J. C.↗

Development of a chemiluminescent and bioluminescent system for the detection of bacteria in wastewater effluent

Automated chemiluminescent and bioluminescent sensors were developed for continuous monitoring of microbial levels in wastewater effluent. Development of the chemiluminescent system included optimization of reagent concentrations as well as two new techniques which will allow for increased sensitivity and specificity. The optimal reagent concentrations are 0.0025 M luminol and 0.0125 M sodium perborate in 0.75N sodium hydroxide before addition of sample. The methods developed to increase specificity include (1) extraction of porphyrins from bacteria collected in a filter using 0.1N NaOH - 50 percent Ethanol, and (2) use of the specific reaction rate characteristics for the different luminol catalysts. Since reaction times are different for each catalyst, the reaction can be made specific for bacteria by measuring only the light emission from the particular reaction time zone specific for bacteria. Developments of the bioluminescent firefly luciferase system were in the area of flow system design.

Thomas, R. R.↗

An analysis of the market potential of water hyacinth-based systems for municipal wastewater treatment

The potential U.S. market for tertiary municipal wastewater treatment facilities which make use of water hyacinths was investigated. A baseline design was developed which approximates the "typical" or "average" situation under which hyacinth-based systems can be used. The total market size for tertiary treatment was then estimated for those geographical regions in which hyacinths appear to be applicable. Market penetration of the baseline hyacinth system when competing with conventional chemical and physical processing systems was approximated, based primarily on cost differences. A limited analysis was made of the sensitivity of market penetration to individual changes in these assumptions.

Robinson, A. C.↗

Quantitative mapping of suspended solids in wastewater sludge plumes in the New York Bight apex

The purpose of this investigation was to apply the previously reported methodology to remotely sensed data that were collected over wastewater sludge plumes in the New York Bight apex on September 22, 1975. Spectral signatures were also determined during this study. These signatures may be useful in the specific identification of sludge plumes, as opposed to other plumes such as those created by the disposal of industrial acid wastes.

Johnson, R. W.↗

Supercritical water oxidation for wastewater treatment Preliminary study of urea destruction

Supercritical water oxidation is being investigated as a method of treating spacecraft wastewater for recycle. In this process, oxidation is conducted in an aqueous phase maintained above the critical temperature (374 C) and pressure (215 bar) of water. Organic materials are oxidized with efficiencies greater than 99.99 percent in residence times of less than 1 minute. This paper presents preliminary results for urea destruction. Above 650 C, urea can be completely broken down to nitrogen gas, carbon dioxide and water by supercritical water oxidation, without the use of a specific catalyst.

Timberlake, S. H.↗

Addendum: Development of a preprototype times wastewater recovery subsystem

The results of the second generation operational improvements and the TIMES (Thermoelectric Integrated Membrane Evaporation Subsystem) 2 study are covered. Areas covered in the second generation operational improvements are improved temperature control, water quality improvements, subsytem operational improvements, solid handling improvements, wastewater pretreatment optimization, and membrane rejuvenation concepts. The task for the TIMES 2 study are thermoelectric regenerator improvement, recycle loop pH operational criteria, recycle loop component optimization, and hollow fiber membrane evaporator improvement. Results are presented and conclusions are drawn from both studies.

Dehner, G. F.↗

Development of a preprototype times wastewater recovery subsystem, addendum

Six tasks are described reflecting subsystem hardware and software modifications and test evaluation of a TIMES wastewater recovery subsystem. The overall results are illustrated in a figure which shows the water production rate, the specific energy corrected to 26.5 VDC, and the product water conductivity at various points in the testing. Four tasks are described reflecting studies performed to develop a preliminary design concept for a next generation TIMES. The overall results of the study are the completion of major design analyses and preliminary configuration layout drawings.

Dehner, G. F.↗

Measuring Thicknesses of Wastewater Films

Sensor determines when thickness of film of electrically conductive wastewater on rotating evaporator drum exceeds preset value. Sensor simple electrical probe that makes contact with liquid surface. Made of materials resistant to chemicals in liquid. Mounted on shaft in rotating cylinder, liquid-thickness sensor extends toward cylinder wall so tip almost touches. Sensor body accommodates probe measuring temperature of evaporated water in cylinder.

Schubert, F. H.↗

Increasing Maintainability of a Wastewater-Recovery Unit

Modified system leaks less and easier to disassemble for maintenance. Redesign of wastewater-recovery system separates water from urine: improved operation and system easier to maintain. Details of redesign, chiefly affected hollow-fiber-membrane evaporator, described in report.

Dehner, G. F.↗

Treating Wastewater With Immobilized Enzymes

Experiments show enzymes are immobilized on supporting materials to make biocatalyst beds for treatment of wastewater. With suitable combination of enzymes, concentrations of various inorganic and organic contaminants, including ammonia and urea, reduced significantly.

Jolly, Clifford D.↗