This week, NASA revealed that the International Space Station’s Environmental Control and Life Support System (ECLSS) is recycling 98 percent of all water astronauts bring aboard the station..
This week, NASA revealed that the International Space Station’s Environmental Control and Life Support System (ECLSS) is recycling 98 percent of all water astronauts bring aboard the station..
“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.”
This means that for any sample of liquid waste, 98% of that quantity will be converted back into water, while the remaining 2% will be discarded.
I assume it's the content of the waste that you can't recycle. Like for instance, in urine, you have water of course, but there's also urea and any other waste that the body is removing.
So while you may be able to extract the water from it, the "waste" portion of the bodily waste can't be reused, and must be discarded.
Or if you mean what the process is like for extracting and separating the 98lbs water from the 2lbs of waste, this is the NASA document I could find on the Urine Distillation Assembly that was referenced in this post's article.
To sum it up (to the best of my understanding), the urine enters the UDA, and runs through a vacuum-based distillation chamber and recycle filter, which filters out and collects the brine, before sending off the treated water on it's way for storage and use. Based on the diagram, it looks like there's also a pressure control and coolant system connected to the distillation chamber to pull out any gasses that may be released during distillation.