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Although water quality may currently be analyzed on the ground after a flight, long-duration missions will require the capability to perform analyses on-board. If a water purifier fails, contaminants must be detected rapidly and corrective action taken in a timely manner to prevent serious harm to the crew. Many of the possible contaminants which could negatively affect astronaut health are inorganic ions. These ions can be quantified by ion chromatography (IC), although current commercially-available IC's are too large, heavy, and power-intensive to be used on a space mission. These units also require large quantities of caustic chemicals for analysis, which would pose a significant hazard in a microgravity environment. To meet the need for an inorganic water quality analysis device for long-duration missions, Lynntech developed an ion chromatograph tailored for future planned long-duration missions.

Potable and hygiene water availability is a critical requirement for long-duration manned space missions. Frequent water quality testing helps to ensure astronaut health by providing needed feedback on the effectiveness of on-board water purification units. One of the most basic and broad-spectrum indicators of contamination is organic carbon concentration. To meet the need for water quality feedback on the International Space Station (ISS), as well as on planned missions to Luna and Mars, Lynntech is developing a mesofluidic total organic carbon analyzer (TOCA) through the NASA SBIR program. The unit has been designed to operate in the demanding environment of a long-duration manned space mission and addresses the issues of microgravity operation, an operating lifetime of 5 years, low power consumption, simple user interface, robust architecture, and inherent safety.

Water is the single largest resource required for crew sustenance during long-term human space missions. To preserve this resource, water must be reclaimed from waste streams containing minimum concentrations of organic and inorganic impurities. The removal of dissolved ions from waste water is essential to regenerative water reclamation technology for life support systems. The aim of this project was to demonstrate a novel electrochemically driven purification method using tubulated bipolar ion exchange membranes for the separation of dissolved ionic impurities from spacecraft waste water. Generally, electrochemical separation methods have limited applications since they can only be applied to the purification of the water that has a sufficiently high dissolved ion content to make the solution conductive. The new method, however, uses a membrane composed of bilayers of oppositely charged ionically conducting polymers.

The removal of dissolved ions from waste water is essential for water repurification on long-term human space missions. Lynntech, Inc., has demonstrated a novel electrochemically driven purification method using tubulated bipolar ion exchange membranes for the separation of dissolved inorganic impurities as well as charged organic species from waste water. Generally, electrochemical separation methods have limited applications since they can only be applied to the purification of water that has a sufficiently high dissolved ion content to make the water conductive. The novel tubulated bipolar membranes composed of bilayers of oppositely charged ionically conducting polymers can be used to overcome this limitation. This paper deals with the scaling-up of such a device to increase the throughput to process about 100 liters of waste water per day. This is achieved by using stacks of tubulated bipolar membranes.

A high-temperature, low-power electrochemically-driven fluid cooling pump is currently being developed by Lynntech, Inc. With no electric motor and minimal lightweight components, the pump is significantly lighter than conventional rotodynamic and displacement pumps. Reliability and robustness is achieved with the absence of rotating or moving components (apart from the bellows). Lynntech has recently demonstrated the feasibility of long term pump operation at temperatures of up to 100 °C, and extended storage at temperatures as low as -60 °C. Characteristics of the electrochemically-driven pump are described and the benefits of the technology as a replacement for electric motor pumps in mechanically pumped single-phase fluid loops (MPFL), such as that used in the Mars Pathfinder (MPF), is discussed.

A compact, low-power, electrochemically driven fluid cooling pump is currently being developed by Lynntech. With no electric motor and lightweight components, the pump is significantly lighter than conventional rotodynamic and displacement pumps. Reliability and robustness are achieved with the absence of rotating or moving components (apart from the bellows). By employing sulfonated polystyrene-based proton exchange membranes rather than conventional Nafion® membranes, a significant reduction in the actuator power consumption was demonstrated. Lynntech designers also demonstrated that these membranes possess the mechanical strength, durability, and temperature range that are necessary for long-life space operation. The preliminary design for a prototype pump compares very favorably to the design targets of the next generation spacesuit Portable Life Support Systems cooling pump.

The impact on the water recovery and reclamation system resulting from laundry operations has been the primary obstacle to the implementation of a laundry capable for long duration space missions. Such an onboard system can provide improved housekeeping effectiveness and crew health maintenance aspects. Electrochemically generated ozone was used as a laundry (cleaning) agent under simulated washing conditions and compared with Tide® and dodecynlbenzoicsuccinic acid (DBSA). Three aspects were studied: (i) cleaning ability; (ii) disinfection potential; and, (iii) impact on the resulting laundry water. In most instances, ozone provided a detergent-like cleaning ability that was as good as, or better than, Tide® or DBSA. Ozone was a superior disinfectant and, more importantly, had a low impact on the laundry wash water in terms of its potential for recycling.

Monitoring the quality of astronaut potable and hygiene water is one of the highest priorities of a regenerative life support system for manned space missions to the ISS, Moon, Mars, and other remote locations. Real-time monitoring allows analysis of water processing from wastewater to potable water and would enable the rapid diagnosis and correction of a processing failure if a water-related health issue were to arise. Among detectors used to monitor recycled water quality, a total organic carbon (TOC) instrument or its functional equivalent should be used to assess the organic contaminant level. Through the NASA Small Business Innovative Research (SBIR) program, Lynntech has developed a novel, mesofluidic Total Organic Carbon Analyzer (TOCA) for real-time monitoring of water quality. It has been designed for an operational lifetime of 5 years with no maintenance required and no need to supply reagents or water.

The post-treatment purification of water recovered from hygiene, metabolic and humidity condensate waste water is essential to regenerative water reclamation technology life support systems. Lynntech, Inc., working with NASA-JSC has developed an electrochemical reactor that generates ozone and hydrogen peroxide. The electrochemical reactor is the basis for an advanced oxidation process in which electrochemically generated oxidants are used in combination with ultraviolet irradiation to produce hydroxyl radicals in a reclaimed water stream which in turn oxidize dissolved organic impurities to carbon dioxide. This paper describes the design and fabrication of an automated breadboard reactor system based on this principle. The system operates at low temperature and requires no chemical expendables. Kinetics and performance test results are presented showing the removal of organic impurities and disinfection features to produce potable water quality.

A microelectrode-based electrochemical detection method was used for quantitation of bacteria in water samples. The redox mediator, benzoquinone, was used to accept electrons from the bacterial metabolic pathway to create a flow of electrons by reducing the mediator. Electrochemical monitoring electrodes detected the reduced mediator as it diffused out of the cells and produced a small electrical current. By using a combination of microelectrodes and monitoring instrumentation, the cumulative current generated by a particular bacterial population could be monitored. Using commercially available components, an electrochemical detection system was assembled and tested to evaluate its potential as an emerging technology for rapid detection and quantitation of bacteria in water samples.

Electrochemical oxidant generation has been combined with UV photolysis to provide a highly effective means of water purification, decomposition of bacterial organic substances, microbiological control and sterilization. Ozone is an oxidant with many unique features that make it a valuable tool for biomedical applications. It is an excellent bactericidal, virucidal and sporicidal agent making it ideal for use as a sterilant. Combining O3 with UV radiation stimulates formation of hydroxyl radicals (OH·) which accelerates a wide range of organic oxidations. While in some instances maintenance of an oxidant residual is necessary, the residual can be rapidly removed by UV light at the point of use (i.e., Water For Injection). Test results on pyrogen decomposition, bacterial organic decomposition, microbiological sterilization, residual removal and water purification as a final step for producing pharmaceutical grade water are discussed.

The purification of reclaimed water is essential to water reclamation technology life-support systems in lunar/Mars habitats. Lynntech, Inc., working with NASA-JSC, is developing an electrochemical UV reactor which generates oxidants, operates at low temperatures and requires no chemical expendables. The reactor is the basis for an advanced oxidation process, in which electrochemically generated ozone and hydrogen peroxide are used, in combination with ultraviolet light irradiation, to produce hydroxyl radicals. Results from this process are presented which demonstrate concept feasibility for removal of organic impurities and disinfection of water for potable and hygiene reuse. Power, size requirements, Faradaic efficiency and process reaction kinetics are discussed. At the completion of this development effort, the reactor system will be installed in JSC's regenerative water recovery test facility for evaluation to compare this technique with other candidate processes.

The recovery of resources for reuse from the processing of diverse waste materials produced by a crew in space-based closed life support systems is essential for the success of long duration space missions. Lynntech, Inc. is investigating and developing a waste processor that uses thermal solubilization and wet oxidation at elevated pressure and an electrochemical process for solid waste processing for closed life support systems. The electrochemical process uses a packed bed anode that oxidizes waste at temperatures <100°C and operates at atmospheric pressure. This approach offers an alternative to high temperature thermal processes for solid waste treatment. Incorporated into the packed bed reactor design is a method that shows potential for regenerating a liquid electrolyte enabling the electrochemical process to operate for long periods without having to be replaced.

The development of a new microfluidics based carbon analyzer that is capable of generating chemicals needed in the analysis is described. The analyzer design is based on several components, an electrochemical cell, a membrane conductivity sensor, and an electrochemical water de-ionizer, which utilize porous membranes such as proton exchange membrane, gas separation membrane, and ion exchange membrane n their operation. These membrane-based microfluidic devices (MBMD) allow miniaturization of the carbon analyzer into a compact instrument which will provide high sensitivity and low power consumption. Each of the membrane-based microfluidic components was fabricated and their functioning tested over a broad range of inorganic or organic carbon content in water samples.

In bioregenerative life support systems, crop residues represent a source of biochemical energy for production of chemicals, pulp products and secondary foods. Hydrolysis of the structural carbohydrates in biomass produces edible glucose as well as various 5-carbon sugars usable by microorganisms. However, the biomass must be pretreated before hydrolysis to remove minerals useful as plant nutrients, break down lignin, and improve access of the enzymes to the carbohydrates. Some pre-treatments also hydrolyze part or all of the hemicellulose, leaving purified cellulose. For use in space, pretreatments must be safe, rapid and as complete as practicable. This paper will present a process comparison of three “space-compatible” pretreatment methods for lignocellu-losic crop residues from bioregenerative life support systems. Ozonation, alkaline hydrogen peroxide, and strong alkali treatment use only regenerable materials and mild processing conditions.

Practical solar powered aircraft require an efficient energy storage system to store energy during the day for use at night. Hydrogen and oxygen, generated by electrolyzing water during the day and recombined at night to generate electricity, has a theoretical energy density of 3.73 kWh/kg. Harnessing this potential has been approached with a combination of a lightweight PEM electrolyzer and a lightweight PEM fuel cell with a new stack structure utilizing metallurgical bonding to assemble thin metal gas barriers with lightweight metal flow fields. This design minimizes size, weight, electrical resistance, and part count. This technology has been demonstrated to produce efficient and effective stacks.

This paper addresses the development of a novel technology to simultaneously reduce total organic carbon (TOC) and microbial count (MC) in biological water processor (BWP) processed water. This approach also creates a biocidal environment in BWP processed water before being fed into the reverse osmosis (RO) and post processing systems. The technology is based on an advanced oxidation process using an on-demand oxidizer generator, which does not require consumable chemicals. The SBIR (Small Business Innovation Research) Phase I feasibility studies successfully demonstrated the process efficacy in the reduction of both TOC and MC of the BWP effluent. Also, the residual disinfectant and reduced TOC in the treated effluent minimized fouling the RO membrane and water lines. In the Phase II project, a prototype is being fabricated and evaluated for its ability to reduce TOC and MC, and extend RO membrane life.