Postcards from Space: Life Support Technology to support long-distance space travel
Dries Demey, Senior System Engineer
Life Support Systems ensure that astronauts can live in a comfortable and safe environment with conditioned air, oxygen, food, water, and waste evacuation. Advanced Life Support Systems consider waste as a resource and aim for recycling of air and water after appropriate treatment and conditioning.
QinetiQ’s space business is helping to develop and demonstrate new Life Support Systems technology. Among our current projects are the Waste Compartment and Microbial Electrolysis Cell (WC-MEC) and support for the exploitation of the water production and recycling system at the Princess Elisabeth Research Station.
Microbial Electrolysis Cell
Production of bio-hydrogen has the potential to be a renewable energy alternative to current technology. A Microbial Electrolysis Cell (MEC) is a bio-electrochemical system that is capable of producing hydrogen gas at a much better energy efficiency rate when compared to classical electrochemical hydrolysis. Electrochemical hydrolysis of water requires 4 to 5 kWh of energy for the production of 1 m³ hydrogen, while MEC systems consume hardly any energy as bacteria are the catalyst for the reactions.
Sanitary waste water contains organic contaminants that are fermented into water soluble fatty acids. The fermented waste water is fed to a MEC cell with an anode and cathode chamber separated with an ion selective membrane allowing transport of ions between the compartments. Bacteria grow on the anode and oxidize the fatty acids present in the water. By this process, an electron is released and transported to the cathode. In the cathode chamber the electron reacts with production of hydrogen as a result. A voltage of about 0.5 to 1 Volts Direct Current is applied to the cell to drive the bio-electrochemical reactions. So, the current production is directly proportional to the hydrogen gas produced.
In collaboration with the Center for Microbial Ecology and Technology part of the Faculty of Bioscience Engineering at Ghent University, QinetiQ’s space team has developed and constructed a pilot installation to demonstrate the technology and to quantify the processes. The installation is fully automated and equipped with instruments to allow a verification of the mass balances. Based on the experiments, it will be possible to quantify the hydrogen production rates in relation to the converted organic contaminants. The work is performed for the European Space Agency in the framework of the MELISSA program focusing on innovative technologies for Life Support Systems.
Drinking water at the Princess Elisabeth Research Station
Copyright: International Polar Foundation - René Robert
QinetiQ is also supporting the International Polar Foundation in the operation and exploitation of the water treatment and production facilities at the Princess Elisabeth Station near Utsteinen on Antarctica.
The Princess Elisabeth Station was constructed about 10 years ago on the initiative of the International Polar Foundation. In accordance with the Antarctic Treaty, the “zero-emission” concept of the station limits the impact on the environment and renewable energy is generated by solar panels and wind turbines. Waste and waste water also needed to be treated and reused.
The design and implementation of the technical systems to achieve this was found to be challenging due to the constraints on available space, energy supply, hostile environment and logistics. These requirements are very comparable with those applicable for space systems.
Therefore, the International Polar Foundation asked QinetiQ to evaluate the existing water management systems and to propose an action plan for upgrading the existing systems. A partner agreement was established with the aim to promote the station as a reference platform for future Life Support Technology for Manned Space Exploration.
The water management system includes several units. These are located in the central technical core of the building. At the start of every season, snow is melted to produce potable water. The melting water is conditioned and stored. The water is distributed to the kitchen, showers, toilets, and laundry. Waste water containing particles from metabolic waste and food leftovers is identified as ‘black water’. Water with a lower organic load from showers, laundry and cleaning is called ‘grey water’.
The waste water treatment system combines biological and physical-chemical treatment technology. The water is transferred to an anaerobic bioreactor in which fermenting bacteria degrade the particles into smaller soluble molecules in the absence of oxygen and at high temperature (55°C). The process ensures also elimination of pathogenic microorganisms. The reactor content is filtered over ceramic membranes and the filtrate is forwarded to the aerobic treatment system and further processed together with the grey water. In the aerobic system, soluble organics are biodegraded and converted to CO2 and N2. The water is separated from the bacteria by a flat sheet membrane filtration unit. The effluent is finally polished in an activated carbon column and after chlorination stored in the distribution tank for reuse via the tap water circuit.
During the season of 2018-2019, the units were refurbished and expanded successfully to increase the treatment capacity according the increasing number of crew and scientists present at the station. At the end of the season, a treatment efficiency of about 90 % was achieved of all the waste water. Water was reused as toilet flush and shower water. Drinking water for human consumption was still produced from melted snow. The distribution system was adapted to guarantee a good microbial quality of the water.
The actions for season 2019-2020 include an improvement of the start-up and shut down procedures to allow the systems to work a full capacity as soon as possible. This includes a further automation of the system. New analyzers to measure the water quality were purchased and will be used as feed-back for advanced control algorithms that support the operator in taking decision and to provide early warning in case of anomalies.
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