NASA System Recaptures Water From Urine

Imagine that you were on the adventure of a lifetime, exploring outer space
and – literally – going where no one has gone before. Oh, and there’s just
one catch; you’ll need to recycle your own urine into drinking water. That’s
now reality for the astronauts aboard the International Space Station. In
November, the space shuttle Endeavor delivered NASA’s Water Recovery
System (WRS) and after a few initial glitches, it appears to be functioning well.




Orbiting 250 miles above our planet, the International Space Station is an
outpost for humanity tethered to our world only by gravity. Supplying the
station with water has always been an issue; the cost per pint tops $15,000 US.
As such, the astronauts had always relied on recycling and water reclamation
was a necessary fact of life. The crew of the station had to recapture
every possible drop: water evaporated from showers, shaving, tooth brushing
and hand washing, plus perspiration and water vapor that collects within
the astronauts’ space suits. In a pinch, they even transferred water from
the fuel cells that provide electric power to the space shuttle, but one
frontier of reclamation lay untapped: the astronauts’ own urine.
Image courtesy of NASA
NASA’s Water Recovery System

The WRS mimics the water cycle of our own planet, evaporating and
re-condensing the water and then passing it through filters that capture
and remove any remaining contaminants. Going into a bit more detail, the
new system distills urine then shunts it to join the rest of the recovered fluids
in the water processor. The processor filters out solids such as hair and lint
and then sends the wastewater through a series of multifiltration beds, in
which contaminants are removed through adsorption and ion exchange.
After that, a reactor that breaks down any remaining compounds to carbon
dioxide, water and a few ions. After a final check for microbes, the water is
again clean and ready to drink.
NASA, the Russian Space Agency and most scientists see urine recycling as
a logical ‘must have’ for interplanetary travel. Furthermore, once at their
destination – say Mars – the explorers will most likely need to continue water
recycling until a permanent settlement is in place, even if local water sources
exist. While every effort would be made to land the exploration crew near ice
deposits, until that ice is proven ‘clean’ and fit to drink, the crew will need to live
as they had for the journey.
The initial few days of testing the new WRS were frustrating to the crew and
mission controllers. The WRS seemed to be unable to run for more than four
hours without being restarted. Finally, the problem was identified as a
poorly-mounted centrifuge. Astronauts Mike Fincke and Don Pettit changed
how the centrifuge was mounted in the unit and the WRS began running smoothly.
NASA has stated that it plans to test the recycled urine for any contaminants
and to make sure that the system works as well in microgravity as it did on Earth.
If all goes well, the crew of the International Space Station will get the go-ahead
to use the WRS unit full-time in 2009.

California’s Water Allocation Plan

On October 29th of 2008, the California Department of Water Resources (DWR)
announced that it would be allocating only 15% of the water requested by the
communities served by the State Water Project (SWP) in the State California;
this represents the second lowest allocation level in over 40 years. Several factors
have contributed to this conservative plan including a prolonged drought in the
region, lower than average snowfall, and a court decision to protect a small fish.
The California DWR is tasked with taking this all into account and managing the
State’s fresh water resources; a difficult task even in a wet year.


California, and indeed most of the southwest United States is in the midst of
a multi-year drought. Lower than expected rainfall has been recorded for the
past 2 years, and that trend is projected to continue in 2009. In fact the
pattern of repeated drought is well known to archeologists who study the
ancient cultures of the Southwest and to the Native Americans and settlers
who lived through such cycles. To overcome this hurdle, the State of California
began to build a system of canals, dams and reservoirs decades ago; this work
is ongoing and the DWR is currently the state agency tasked with the
maintenance, repair and construction of these facilities. These structures
have the effect of ‘leveling’ the wet and dry cycles, allowing the State to
collect and preserve a large percentage of the rainfall and snowmelt in the
wet years and then use that to sustain the State’s water demand during
the dry years.


Over the past two decades, California has seen two trends which both
contributed to the current low reservoir levels. The first is the increase in
population seen by California; over 15 million new citizens came to the state
in the past 30 years, almost doubling the population. This growing populace
obviously puts a greater demand on the state’s water supply, siphoning more
water from the reservoirs than planners 50 years ago expected. The second
factor may be more of a surprise; the past 30 years have been fairly wet years
and the State of California regularly had ‘surplus’ water. This bounty was one
of the main reasons that California’s Central Valley saw such agricultural
productivity during these years. Certainly there were dry periods, but on the
whole, the State experienced some of its wettest years in the 20th century from
1978 to 1998, the graph below from the University of California at San Diego
reinforces this point. The graph also gives some insight into the lag that
accompanies the rainfall cycle; for several years at the beginning of a ‘dry’
period, the groundwater supplies appear to be bountiful. This effect, however,
is only temporary and the abundant supply quickly disappears; California
appears to be entering this plunge to drought, currently.

Water Years

Figure 1 – The total annual rainfall (top) shows the wet and dry years;
the cumulative residual water (bottom) lags behind the rainfall trend by several
years.

Another interesting factor in California’s water dilemma is, of all things, a fish.
In 2007, a Federal District Court judge protected the delta smelt, citing its
declining population and short lifespan as reasons for protection. The delta
smelt is a small, silver fish approximately 3-4 inches long; it lives in the San Joaquin-Sacramento River and has a one year lifespan. As a result of the short lifespan,
it is believed that the delta smelt is more prone to be affected by yearly variances
in water levels, as such; the judge limited the use of the Banks Pumping Plant
from December to June. As it happens, these pumps generate the water
pressures which allow the California and South Bay aqueducts to reach their
destinations. Because of this court ruling, the State of California lost the ability
to deliver approximately 625,000 acre-feet of water to central and southern California.

The State’s Governor, Arnold Schwarzenegger, has proposed building new dams
and channels to avoid the environmental issues associated with the delta smelt
and has been caucusing with other governors in the region to reach a common
understanding that may help to ease the situation. In the meantime local water
managers, faced with reservoirs that are less than half-full, are calling for
immediate reductions in use by farmers and households. If the State’s water
allocation plan holds at 15%, many fields will sit idle this summer. Of course,
a wetter winter or greater than expected snowfall would allow the DWR to
upwardly revise their allocation; this happened last year when the DWR initially
projected a 25% allocation and then later revised that to 35% after a wet winter.
But that isn’t a guarantee and the DWR’s conservative planning appears to be
warranted at this time. Looking forward, however, it appears that the State of
California needs a revision to its water plan, one that plans on much less water
availability for the next several years.