Q and A: Recycling Astronaut Urine

BB: Well, I usually like to see if knowing where it comes from if they're still willing to go ahead and drink it.

IK: And do they? What's been the response?

BB: Yes, people have a natural curiosity about it.

IK: How does this system work? How does an astronauts' urine go through the process of becoming water for his oatmeal in the morning?

BB: Urine is collected and temporarily stored in storage tanks and then it goes through a process called vapor compression distillation. That's just a long word for a boiling process in which we generate a relatively purified steam from the urine. We do that in a distillation process that we had to optimize for operation in microgravity. In microgravity, the vapor and the liquid tend to not separate like they do on Earth. The distillation process actually rotates to create some gravitation forces within the fluid that then allow the vapor and the liquid to separate. That steam that we generate is then obviously much cleaner than the urine from which it was derived, but still is not nearly clean enough for astronauts to drink. So we then combine that distillate with the humidity condensate that's collected from the air conditioning systems of the space station and that combined mix then flows though the remainder of our system.

There are a number of steps. The first thing we do is remove any residual gas or trapped air from the water. Doing that in microgravity requires a unique step. We use a rotary separator again to induce gravitation forces that will separate that gas from the liquid. From there, we then pass the water through a relatively standard filtration device that will remove a solid particulate matter from the water -- hair, lint, skin cells -- relatively minor things, but stuff that still needs to be taken out nonetheless.

Next the water goes though multi-filtration beds -- our name for some treatment beds that include a combination of filtration media, much like you can find in commercial-off-the-shelf devices that are sold to treat tap water at home, things like activated carbon and ion-exchange resins. The water that comes out is pretty clean but there are still some trace organic material contaminants in the water, so the next thing we do is process the water through a catalytic oxidation process. That's just a fancy name for a processor where we add oxygen, we heat the water up to a very high temperature, we run it over a catalyst and under those conditions those trace organic contaminants are converted to other chemical forms that make them subsequently removable by traditional ion exchange resins that we have downstream.

We run the water through an ion exchange bed, add iodine to the water and at that point it is now potable water, meets our water quality requirement. The water is stored in a tank and is available for use whenever the crewmembers have a need.

IK: How long does it take for all that to happen?

BB: We can process a full days worth of wastewater in less than 24 hours, so today's drinking water was yesterday's waste.

IK: What's your background?

BB: I'm a chemical engineer by training.

IK: So in your wildest dreams, did you one day imagine that you'd be recycling pee?

BB: No, I certainly didn't imagine that. When I was a kid I was always kind of fascinated with the space program, built rockets and all those kinds of thing. When I finished college and got my chemical engineering degree, even then I didn't think that I had much of a match for the space program. It wasn't until NASA contacted me looking for someone with my background that I made the connection. As an engineer, there's nothing more exciting and rewarding to work on than the space program. One of the most rewarding things about of my particular part is relatively so few people are working on what I work on. It is pretty neat being part of a relatively small number of people who do this kind of thing for a living.

IK: So after a designing a system that lets people drink their urine and perspiration, what's next for you? 

BB: I've been transitioning out of my space station job to supporting the exploration program, in particular I'm supporting architecture studies about how we would design and operate an outpost on the lunar surface.

IK: You've sort of moved on from designing the bathroom and plumbing systems into looking at the whole house?

BB: No, I'm still the bathroom-and-kitchen guy, but the house is now on the moon.

Got something to say? E-mail your questions, comments or concerns to discoveryspace@discovery.com.

MORE INTERVIEWS

Related Links:

Slide Show: Happy Birthday, NASA

Discovery Space for interviews, photos and more

Free Space Blog