NASA Testing Breakthrough In Water Safety

Jerry James Stone writes "NASA and University of Utah chemists are developing advanced tech for testing the drinkability of water. The process just began a six-month run aboard the International Space Station. Water will be sampled either from the Space Station's or Shuttle's galley using a syringe. It is then forced through a chemically-imbued membrane, which changes color based on toxicity. The process itself will take about two minutes. It checks drinking water for iodine and silver, which are used to kill unwanted microbes."

Comments

Bad article, !toxicity

[clone53421]

They aren't testing toxicity, they're testing for effective disinfection (by ensuring there is the correct residual disinfectant remaining in the water). That's pretty uninteresting, actually. It's standard practice to test for a disinfection residual in the water treatment industry.

Common disinfectants are chlorine (either gaseous or in hypochlorites, e.g. sodium hypochlorite = liquid bleach, or calcium hypochlorite which is in the form of solid granules or tablets), chloramines (a chlorine/ammonia compound), ozone, and ultraviolet. Ultraviolet, of course, is a one-time hit and leaves no residual disinfecting agent in the water. Ozone dissipates quite rapidly, so the residual is gone in a short matter of time. Chlorine dissipates over the course of several days, while chloramines stay in the water for several weeks. Large water systems typically need a disinfectant which will stay in the water for several days or weeks, because it takes that long for the water to travel from the treatment plant out through the piping system to the edges of the distribution region. You have to have an adequate disinfectant residual even at the edges of your system in order to prevent microbial growth inside your pipes.

Frankly, I'm very not-impressed with TFA. This is somewhat better, it at least explains the disinfection process and why they need to test for these two substances (iodine and silver):

NASA uses iodine as a disinfectant on U.S. space crafts, and Russians use pure-silver nanoparticles that at low levels are non-toxic, but it's a balancing act. If the levels of iodine and silver in the water are too low, microbes will grow, Porter said. Levels of iodine that are too high result in bad-tasting water that the astronauts will not drink, putting them at risk for dehydration. A long-term effect of drinking an excess of iodine is the possibility of developing thyroid problems. Excess levels of silver can permanently turn the skin a grayish-blue color.

Of course, if you really want the low-down on the process, you get it from NASA's website...