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How is water filtered on the ISS?


jzermeno said...

The International Space Station (ISS) inhabitants will join the world in the effort of recycling. This recycling will be different from that which may take place in your home or school. The astronauts will be recycling their water. This includes the moisture they exhale, sweat, shower and shaving water, and even urine. These waste waters will be purified and then used as drinking water. Biological treatments are used to purify water on Earth. This process uses microorganisms to destroy contaminants in the water. The ISS will use physical and chemical processes to remove contaminants. The Urine Processor will remove contamination in the urine using distillation (heating of a liquid to prevent microbial growth). Components that cannot be eliminated will remain as a liquid urine, which will be returned to Earth and disposed. The ISS will also use filtration and temperature sterilization to ensure the water is safe to drink. Water will be checked often to ensure it meets the water quality requirements and monitored closely for bacteria, pollutants, and proper pH (a measure of the acidity or alkalinity in the solution). The pH scale ranges from 0 to 14. Substances with a pH value of 7 are neither acidic nor basic. Pure water has a pH value of 7. The lower pH value indicates higher acidic levels; the higher the pH value the more alkaline the substance is. Public water systems have to meet a pH level of 6.5 to 8.5. Even though the Space Station water system specifications range from 6.0 to 8.5, the recycled water on the International Space Station is almost sterile and much better than water from a tap at home or at school. There is no odor or bad taste. For Space Shuttle missions, it is not necessary to recycle the water or waste products. The Shuttle fuel cells produce water as a byproduct; however, water recycling will be imperative for long-duration missions such as on the Space Station or possible trips to Mars. There will be no fuel cells on the Space Station; therefore, water will not be produced. In addition, a spacecraft on a lengthy trip to Mars would be limited to the amount of water it could carry because of weight restrictions.

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