FOR RELEASE: May 5, 1997

Greg Shell
Office of Media Services
(205) 544-0034

Release: 97-065

SPACE STATION WATER PURIFICATION SYSTEM PASSES TEST WITH FLYING COLORS

Imagine taking all the water you use or produce in your home -- including perspiration, shower and shaving water, even urine -- and recycling it into fresh drinking water.

Well, a NASA team at Marshall Space Flight Center in Huntsville, Ala., is wrapping up testing on a system that will do just that for astronauts aboard the International Space Station.

Next year, NASA and its international partners will begin assembly of the Space Station -- a permanent, orbiting laboratory where astronauts will live and work year-round. Weight and storage limitations will make continued recycling of water necessary, and even then, water will be rationed.

The water recycling system planned for Space Station has now completed a major series of tests at Marshall and researchers are giving it high marks.

"We are very pleased with the results," said Layne Carter, principal investigator for Marshall's Space Station Water Recovery System Project.

The system collects and recycles all the water in the environment including humidity from respiration, perspiration and microwave use; waste water from showers, hand washes, shaves, and toothbrushes; and urine.

Eighty volunteers participated in the six-month study to evaluate the efficiency of the system. Each day approximately 20 of the volunteers would each complete an hour of activities -- exercising, eating, showering, washing their hands, shaving, brushing their teeth, and using the bathroom -- in the test facility.

On Earth, water treatment plants use biological treatment to purify the water. Microorganisms metabolize and destroy contaminants. In contrast, the Space Station water recovery system uses physical and chemical processes to remove contaminants.

The Space Station Urine Processor uses distillation to evaporate and remove more volatile components of urine, including the water. Less volatile and less desirable components remain as a liquid brine, which eventually has to be disposed of as waste.

The Space Station Water Processor uses four technologies to purify the water. These technologies include particulate filtration, ion exchange, carbon adsorption, and catalytic oxidation. Following these steps, iodine is added as a microbial biocide, similar to the use of chlorine in most municipal water systems. Last of all, the quality of the water is monitored to ensure the purification process is working and water quality is acceptable.

Acceptable water is sent to the product tank for use by the crew; unacceptable water is recycled through the Water Processor until it meets the water quality requirements.

The system successfully recycled and purified the waste water into potable water for 146 days, including the first 128 days in which the product water was recycled for use by the volunteers. "This is significant," said Carter, "because of the concern that contaminants not efficiently removed by the system would begin to accumulate after extended recycling."

Of course, a significant measure of the system's success was the taste test, and it passed that test too. "Test subjects said the water was very acceptable for drinking," said Carter, "-- no bad taste or odor."

"And the system was able to remove all microbes -- health hazards -- from the water," said Monsi Roman, chief microbiologist for the Space Station life support system.

Viral test procedures for the system were developed as a cooperative effort by Marshall and the Environmental Protection Agency (EPA).

"During testing, a mixture of four viruses was added to the water," said Dr. Christon Hurst of the EPA Microbial Contaminants Control Branch.

"Only viruses capable of infecting bacteria were used so there was no risk to the volunteers participating in the study." The water was then processed through the system. Test results show that the water processor is capable of removing all viruses present in the waste water.

Conventional biological water processing systems -- like the ones used on Earth -- are also being studied for future use in space, but "they are not a desirable option for the Space Station because they require significantly more volume than the physiochemical approach and can easily fail if the operating conditions are not well maintained," said Carter.

The processing system being developed for Space Station can efficiently recycle water containing a high concentration of contaminants. The less water used, the higher the concentration of contaminants.

"The system is very efficient," said Hurst -- "10,000 times better than the average water treatment plant. And it has to be. On board the Space Station, water will be rationed, so there will be a much higher concentration of contaminants than we deal with on Earth."

"The system is also much more compact than a conventional biological processor," said Carter -- a plus because of Space Station's weight limitations.

"The Space Station's water recovery system is very efficient and reliable," said Carter, "and provides water that is much cleaner than municipal drinking water in terms of both chemical and microbial contaminants."

The water recovery system is one of seven systems which will work

together as the Space Station's Environmental Control Life Support System. "It will provide basic needs to sustain life -- air, water and food -- where Earth's natural life support system cannot," said Roman.

For short-duration missions, it is not necessary to recycle air, water or waste since sufficient quantities can be taken along. But with long-duration missions -- such as Space Station or a venture to Mars -- it is necessary to recycle as much as possible to reduce resupply and storage requirements.

The Space Station water recovery system also could have applications for water processing on Earth. "One area where it might be applicable is in geographical areas where temperature is a factor," said Hurst, "such as the basins of Antarctica where biological processes don't work due to extremely cold temperatures. Physiochemical processes, like the Space Station system uses, could work there."

This was the sixth of seven planned tests of the water recovery hardware -- all the hardware required to recover and recycle water and urine. Testing began in May 1990. The next stage of testing is scheduled to begin in mid-1998. After testing is complete, the system will be ready for integration into the habitation module -- or living quarters -- of the Space Station.

NOTE TO EDITORS: Photographs are available to support this release. Contact Joy Carter at Marshall Space Flight Center at (205) 544-6849 or the Office of Media Services at (205) 544-0034.

Prepared by Joy Carter