Aquaporin Inside Membrane Testing in Space (AquaMembrane) - 10.04.17

Overview | Description | Applications | Operations | Results | Publications | Imagery

ISS Science for Everyone

Science Objectives for Everyone
The Aquaporin Inside Membrane Testing in Space (AquaMembrane) investigation helps to validate an Aquaporin Inside Membrane (AIM) as a replacement for the International Space Station (ISS) multifiltration beds for water recovery. This is done by quantifying AIM efficiency in treating ISS condensate water, obtained from moisture in the ISS cabin atmosphere. This could lead to improved efficiency in ISS systems for reclaiming water, which can help to reduce the upload mass of expendable media used in water processing.
Science Results for Everyone
Information Pending

The following content was provided by Maja B. Tommerup, B.Sc., M.E, and is maintained in a database by the ISS Program Science Office.
Information provided courtesy of the Erasmus Experiment Archive.
Experiment Details

OpNom: AquaMembrane

Principal Investigator(s)
Maja B. Tommerup, B.Sc., M.E, Aquaporin Space Alliance, Odense, Denmark

Jörg Vogel, Ph.D., Aquaporin A/S, Copenhagen, Denmark
Michael Flynn, NASA Ames Research Center, Moffett Field, CA, United States

Aquaporin Space Alliance Aps, Odense, Denmark

Sponsoring Space Agency
European Space Agency (ESA)

Sponsoring Organization
European Space Agency

Research Benefits
Information Pending

ISS Expedition Duration
March 2015 - March 2016; September 2016 - April 2017

Expeditions Assigned

Previous Missions
Information Pending

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Experiment Description

Research Overview

  • Fresh water is essential for life on Earth and in space, and in both cases, the use of filtration systems is an essential part of the process of supplying water in sufficient quantities. On the ISS, the Water Recovery System racks use filtration beds to reclaim water on the ISS and hence, supply some of the drinking water to the crew and water used in, for example, cooling systems in the spacewalking suits. This greatly reduces the upload mass in connection with water supplies. However, making improvements in the efficiency of the filtration processes could further reduce upload mass and associated costs.
  • The Aquaporin Inside Membrane Testing in Space (AquaMembrane) investigation tests a replacement to the ISS multifiltration beds to help validate an Aquaporin Inside Membrane (AIM). It will demonstrate the function of AIM test apparatus in space and quantify its efficiency to treat waste water (urine distillate + condensate obtained from the ISS cabin atmosphere). The investigation should hopefully confirm ground tests that indicated the membrane was successful at filtering out certain semi-volatile substances, and exceeds the performance of the ISS multifiltration beds.

Information Pending

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Space Applications
This technology experiment could lead to improved efficiency in ISS systems for water filtration for use as drinking water etc., which can help to reduce the upload mass of expendable media used in water processing. These improvements could also have a positive impact for future exploration mission planning with respect to water filtration and surface Extravehiclar Activities, by reducing upload costs and improving safety and system life.

Earth Applications
With the growing scarcity of fresh water, more and more interest is being paid to the desalination of seawater and brackish water. Among the various desalination technologies, reverse osmosis is the most common. Here, the aquaporin-based biomimetic membrane can potentially achieve a water permeability two orders of magnitude higher compared to existing reverse osmosis membranes. Recently, however, an alternative technology (forward osmosis) has stepped into the market of water treatment. The AIM is especially developed for this forward osmosis technology and has shown unique capabilities in ground testing.

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Operational Requirements and Protocols

The Aquaporin Inside Membrane Testing in Space (AquaMembrane) experiment is a manually operated soft product type experiment. AquaMembrane requires no power or thermal control to conduct the experiment. Each test requires about 1 to 2 hours of crew time over a maximum of a 10 hour period. Analyses of product fluid on-orbit require measuring fluid volumes in a storage bag. Experiment operations can be performed in any part of the ISS, and can be performed at any time during the on-orbit stay. The experimental flight payload is derived from a system already flown on STS-135. Waste Water is collected from sampling ports on the ISS Water Processor Assembly (WPA) and shall be used within one week. The experiment requires the fluid samples to be returned to Earth for analysis from the setups. A total of 7 samples of 50 ml need to be collected. Samples can be stowed at room temperature. The samples need to be returned to Earth and handed over to the PI for ground analysis a maximum 6 month after first experiment execution.
Procedure Outline
Flight payload description The flight payload for all the experimental configurations tested is composed of syringes, plastic storage bag, plastic tubing, tubing clamps, stopcocks, plastic strips, parafilm, and the AIM module. Some of the items used for AquaMembrane have flown before. Two different setups are to be tested. They are a Pressure Driven Setup, and an Osmotic Driven setup. The following sections describe each of these configurations.
Pressure Driven Setup
This configuration is used to treat ISS Waste Water to verify microgravity total organic carbon rejection. This configuration is composed of four distinct parts: a bag with Waste Water collected from the ISS Water Processor Assembly (WPA Bag), two feed syringes and the Pressure Driven Setup. All assemblies include 3-way valves, plastic tubing, tubing clamps, integral luer locks, plastic strips, and parafilm. The AIM and tubes are previously filled with Milli-Q Water on the ground. The Saline Product Bag and the Buffer Bag are vacuum evacuated, and the Saline Bag is pre-filled with 150 ml of saline water (Milli-Q mixed with sodium Chloride; 30g/L) on the ground. ISS Waste Water is provided in three sample bags with 300 ml of volume. The ISS Waste Water is tapped from the WPA in Node 3 by NASA, and delivered for the AquaMembrane experiment, and shall be used within one week from tapping date.
Before the test begins the WPA Bag and Waste Water Sample syringe attached and a sample is drawn from the unprocessed Waste Water for ground analysis comparison.
The pressure driven test is completed by attaching both of the feed syringes and open stopcock 3 and 4. Hereafter is Waste Water from the WPA Bag manually pulled into Feed Syringe 1 and pressed into the AIM, to replace the Milli-Q Water on the lumen side of the fibers, followed by manually pulling OA water into Feed Syringe 2 and pressing it into the AIM to replace the Milli-Q Water on the shell side of the fibers. All the stopcocks are turned open to all ways so water can flow freely after the fluid have been pressed through. This step is repeated 6-10 times during a 6 hour period, with a minimum of 1 hour between 10 ml from each feed syringe is pressed through the AIM. If/when the syringes are emptied, they are filled again from the WPA and OA Bag, and repeat the 10 ml pressing. If the WPA and OA Bag get emptied, 10 ml is pulled into the syringes from the Storage and Byproduct Bag.
The ratio of the syringe volume used and the dead volume of the AIM feed side determines the water recovery ration (RR). The RR is determined experimentally on the ground prior to flight, and the syringe is sized accordingly. The volume of the Milli-Q Water that has been pre-charged into the AIM on the ground is corrected for as a dilutant. After end test a sample, 50 ml are drawn from all three setups, and all samples (total 4) are prepared for return to Earth for analysis. The entire assembly is contained in a plastic bag during testing to insure secondary containment. The bag has Velcro for securing the setup during test.
Osmotic Driven Setup
This setup is used to evaluate the effect of concentration polarization on membrane flux rates. This configuration is pre-assembled on the ground to avoid air bobbles being introduced during assembly. The Feed Bag, AIM assembly, connecting hoses, and stopcocks are prefilled with Milli-Q Water. The AIM, hoses, and stopcocks are fully filled, and the bag contains 100 ml Milli-Q Water. The Draw Bag is filled with 200 ml salt water (250g sodium chloride per 1L Milli-Q Water). The test is done by opening stopcock 2 and 3, pulling 50 ml into the Mixing Syringe, and pushing it back again. This is repeated 2 more times. Afterwards, stopcock 2 is closed towards AIM, and stopcock 1 is opened. The setup is left for 2 hours before closing stopcock 1 and 3 towards AIM, rolling up both the Feed and the Draw Bag, and reporting the volume values. Hereafter, stopcock 1 and 3 are reopened. This measuring is repeated at 4, 6, and a minimum of 10 hours. At the end of the test, 50 ml samples are drawn with a syringe from the Draw Bag and prepared for return to Earth. The samples with sodium chloride concentration are analyzed on ground.
The objective of this test is to measure the rate of osmotic flux across the membrane. This is done by opening the stopcock at the Feed and Draw Bag and leaving it for minimum 10 hrs. The flux is determined by measuring the amount of water removed from the Feed Bag, and added to the Draw Bag. This is done by closing the stopcock at the Feed and Draw Bag, rolling the bags up to collect all the water in one end of the bag, and then reading the volume of the calibrated markings on the side of the bag. This measurement is conducted four times during the test, after 2 hours, 4 hours, 6 hours, and at the end (minimum 10 hours). The entire assembly is contained in a plastic bag during testing to insure secondary containment. During volume measurement, the setup is not in this bag since this cannot be performed in the bag. The bag has Velcro for securing the setup during test.
The Feed Milli-Q solution
The feed solution is composed of Milli-Q Type 1 reagent grade water. Water is autoclaved and pre-loaded into sterile storage bags and syringes.
The Saline Solutions
The OA consists of Milli-Q Type 1 reagent grade water with 250g/L of sodium chloride for the Osmotic Driven Setup, and 30g/L for the Pressure Driven Setup dissolved in it. The OA is pre-loaded into sterile storage bags and syringes.
Waste Water
Waste Water is collected from the ISS Water Recycling System (WRS). Specifically, at a point downstream from the condensing heat exchanger prior to the multi-filtration beds. The Waste Water is delivered by NASA from the WPA located in Node 3. 3 bags filled with 300 ml are used for the AquaMembrane experiment. One for each setup.
Ground Reference Experiments
In parallel to or after the actual flight a ground based study is conducted to determine the statistical limits of the flight data, and quantify the reduction in Flux and Total Organic Carbon (TOC).
Planned Analyses
Flux rate is analyzed on-orbit using an increase in volume of the Product Bag as a function of time and decrease in volume of Feed Bag. A total of 7 samples are drawn from the setups, and returned to Earth for analysis.

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Decadal Survey Recommendations

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Results/More Information

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Related Websites
ESA Erasmus database link to information

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