OWhether you live in the rapidly drying American West or are aboard the International Space Station for a six-month stay, having enough water to live on is a constant concern. As climate change continues to wreak havoc on the West’s aquifers and humanity sinks deeper into the solar system, the clean water supply issues we face today will only grow. . , some of NASA’s cutting-edge research on recycling water in orbit is returning to Earth.
In California, for example, runoff from state homes and businesses, storm drains and rooftops, travels through more than 100,000 miles of sewer lines where it – except – eventually ends up in one of the 900 state wastewater treatment plants. . How this water is treated depends on whether it is for human consumption or for non-potable uses such as agricultural irrigation, wetland enhancement and groundwater replenishment.
takes a multi-step approach to reclaiming its potable wastewater. Large solids are first filtered from the incoming fluids using mechanical screens at the head of the treatment plant. From there, the wastewater flows into a settling tank where most of the remaining solids are removed – the sludge is routed to anaerobic digesters after sinking to the bottom of the pool. The water is then sent to secondary treatment where it is aerated with nitrogen-fixing bacteria before being pushed into another settling or clarification tank. Finally, it is filtered through a tertiary cleaning stage of cationic polymer filters where all remaining solids are removed. By 2035, as Aurora, Colorado and Atlanta, Georgia have already begun to increase their drinking water supplies with potable reuse.
“There are additional benefits beyond a safe water supply. If you don’t rely on importing water, that means there’s more water for northern California or Colorado ecosystems,” Stanford professor William Mitch said in . “You’re cleaning the sewage, and therefore you’re not releasing sewage and potential contaminants onto California beaches.”
Wastewater treatment plants in California face a number of challenges, the notes note, including aging infrastructure; contamination from improperly disposed pharmaceuticals and pesticide runoff; population demands combined with reduced flows due to climate change induced drought. However, their ability to provide pure water surpasses nature.
“We expected that reused drinking water would be cleaner, in some cases, than conventional drinking water due to the fact that a much more thorough treatment is carried out for it,” Mitch explained in a study. october in . “But we were surprised that in some cases the quality of reused water, especially reverse osmosis treated water, was comparable to that of groundwater, which is traditionally considered the highest quality water. .”
Solids extracted from wastewater are also heavily treated during recycling. The waste from the first stage is sent to local landfills, while the filtered biological solids from the second and third stages are sent to anaerobic chambers where their decomposition generates which can be burned for electricity generation and converted into fertilizer rich in nitrogen for agricultural use.
New York, for example, from its more than 1,200 wastewater treatment plants (WWTPs) statewide. However, less than a tenth of the plants (116 in particular) actually use this sludge to produce biogas, according to a 2021 report from the , and are “mainly used to feed the facilities and for combined heat and power production. sewage treatment plants”.
Non-potable water can be treated even more directly and, in some cases, . Sewage, storm water and can water the hall plants and toilet flushes after being captured and treated in a (ONWS).
“Increasing pressures on water resources have led to greater water scarcity and growing demand for alternative water sources,” the . “Reusing non-potable water on site is one solution that can help communities recover, recycle, and then reuse water for non-potable purposes.”
Aboard the ISS, astronauts have even less leeway in their use of water because the station is an isolated closed-loop system in space. Also because SpaceX charges $2,500 per pound of cargo (after the first 440 pounds, for which it charges $1.1 million) to send to orbit on one of its rockets — and liquid water is heavy.
While the ISS occasionally receives water in the form of 90-pound duffel bag-shaped emergency water containers to replace what is invariably lost in space, its inhabitants rely on the complex network of levers and tubes you see above and below to grab every possible drop of moisture and turn it into potability. The station’s water treatment package can produce up to 36 gallons of potable water each day from crew sweat, breath and urine. When it was installed in 2008, the station’s water needs . It works in conjunction with the Urine Processor Assembly (UPA), Oxygen Generation Assembly (OGA), Sabatier Reactor (which recombines free oxygen and hydrogen separated by OGA in water) and systems Regenerative Environmental Control and Life Support (ECLSS) to maintain the “ ” and the . Cosmonauts on the Russian segment of the ISS rely on a separate filtration system that only collects shower runoff and condensation and therefore require more regular water deliveries to keep their tanks filled.
In 2017, NASA upgraded the WPA with a new reverse osmosis filter to “reduce the replenishment mass of the WPA multifiltration bed and an upgraded catalyst for the WPA catalytic reactor to reduce temperature and pressure operating,” the agency said. This year. “Although the WRS [water recovery system] has been running well since operations began in November 2008, several modifications have been identified to improve overall system performance. These modifications are intended to reduce resupply and improve overall system reliability, which is beneficial to the current ISS mission as well as future NASA manned missions.
One such improvement is the upgraded Brine Processor Assembly (BPA) delivered in 2021, a filter that removes more salt from astronauts’ urine to produce more reclaimed water than its predecessor. But there is still a long way to go before we can transport crews safely into interplanetary space. NASA notes that the WPA that was delivered in 2008 was originally designed to recover 85% of the water in crew urine, although its performance has since improved to 87%.
“To leave low Earth orbit and allow long-duration exploration away from Earth, we need to close the water loop,” added Caitlin Meyer, deputy project manager for Advanced Exploration Systems Life Support Systems at Johnson Space Center. from NASA in Houston. “Current urinary water recovery systems use distillation, which produces a brine. The [BPA] will accept this water-containing effluent and extract the remaining water.
When the post-treated urine is then mixed with recovered condensation and passes through the WPA again, “our overall water recovery is about 93.5%,” Layne Carter, water subsystem manager water from the International Space Station at Marshall, . To travel to Mars safely, NASA estimates it needs a recovery rate of 98% or better.
But even if the ISS’s current cutting-edge recycling technology isn’t quite enough to get us to Mars, it’s already having an impact on the planet. For example, in the early 2000s, the Argonide company developed a “NanoCeram” nanofiber water filtration system with NASA financial support for small businesses. The filter uses microscopic, positively charged alumina fibers to remove virtually all contaminants without restricting the flow rate too much, which eventually causes.
“The shower starts with less than a gallon of water and circulates it at a rate of three to four gallons per minute, more flow than most conventional showers.” “The system checks the water quality 20 times per second, and the most polluted water, such as the shampoo rinse, is dumped and replaced. The rest passes through the NanoCeram filter and then is bombarded with ultraviolet light before being recirculated. According to the Swedish Institute for Communicable Disease Control, the resulting water is cleaner than tap water.
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