In a significant milestone, NASA said it was able to recycle about 98 percent of urine and sweat from astronauts aboard the International Space Station into drinking water — an advance that can help it in upcoming missions to the Moon, Mars, and beyond.
The feat was achieved by the space station’s Environmental Control and Life Support System (ECLSS) — a combination of hardware that includes a water recovery system.
This system collects wastewater and sends it to the water processor assembly (WPA), which produces drinkable water. One specialized component uses advanced dehumidifiers to capture moisture released into the cabin air from crew breath and sweat.
Another subsystem, the urine processor assembly (UPA), recovers water from urine using vacuum distillation. Distillation produces water and a urine brine that still contains some reclaimable water. Using a brine processor assembly (BPA) developed to extract this remaining wastewater, the astronauts achieved the 98 percent water recovery goal, which was previously “between 93 and 94 percent”.
“This is a very important step forward in the evolution of life support systems,” said Christopher Brown, part of the team at Johnson Space Center that manages the space station’s life support system.
“Let’s say you collect 100 pounds of water on the station. You lose two pounds of that and the other 98 percent just keeps going around and around. Keeping that running is a pretty awesome achievement,” Brown added.
The BPA takes the brine produced by the UPA and runs it through a special membrane technology, then blows warm, dry air over the brine to evaporate the water. That process creates humid air, which, just like crew breath and perspiration, is collected by the station’s water collection systems.
All the collected water is treated by the WPA. It first uses a series of specialized filters, then a catalytic reactor that breaks down any trace contaminants that remain. Sensors check the water purity and unacceptable water is reprocessed.
The system also adds iodine to the acceptable water to prevent microbial growth and stores it, ready for the crew to use. Each crew member needs about a gallon of water per day for consumption, food preparation, and hygiene such as brushing teeth.
The team acknowledged that the idea of drinking recycled urine might make some people squeamish. But they stress that the end result is far superior to what municipal water systems produce on the ground.
“The processing is fundamentally similar to some terrestrial water distribution systems, just done in microgravity,” said Jill Williamson, ECLSS water subsystems manager.
“The crew is not drinking urine; they are drinking water that has been reclaimed, filtered, and cleaned such that it is cleaner than what we drink here on Earth,” Williamson added.
