WWhether you live in the fast-drying American West or are aboard the International Space Station for a six-month period, having enough water to live on is a constant concern. As climate change continues to affect the aquifers of the West and humanity pushes further into the solar system, the drinking water supply challenges we face today will only increase. part of NASA’s groundbreaking water recycling research comes back to Earth in orbit.
In California, for example, the of the state’s homes and businesses, the storm drain and roof-connected drain make its way through more than 100,000 miles of sewer lines where — barring — it eventually ends up at one of the state’s 900 wastewater treatment plants. How that water is processed depends on whether it is for human consumption or for non-potable uses such as agricultural irrigation, wetland improvement and groundwater recharge.
takes a multi-step approach to recovering its potable wastewater. Large solids are first screened from incoming liquids using mechanical screens on the main works of the treatment plant. From there, the wastewater flows to a settling tank where most of the remaining solids are removed – sludge to anaerobic digesters after it sinks to the bottom of the pool. The water is then sent to secondary processing, where it is aerated with nitrogen-fixing bacteria before being pushed into another settling or purification tank. Finally, it is filtered through a tertiary cleaning stage of cationic polymer filters, where any residual solids are removed. by 2035, while Aurora, Colorado and Atlanta, Georgia, have both already begun to increase their drinking water supply with potable water reuse.
“In addition to a safe water supply, there are other benefits. Not relying on importing water means more water for ecosystems in Northern California or Colorado,” said Stanford professor William Mitch in . “You’re cleaning up the wastewater, and that’s why you’re not discharging wastewater and potential contaminants onto California beaches.”
Wastewater treatment plants in California face a number of challenges, the notes, including legacy infrastructure; contamination from improperly discarded pharmaceuticals and pesticide runoff; population demand coupled with reduced flows due to climate change-induced drought. But their ability to provide pristine water surpasses nature.
“We expected that reused drinking water would in some cases be cleaner than conventional drinking water because it undergoes a much more extensive treatment,” Mitch argued in an October study in . “But we were surprised that in some cases the quality of the reused water, especially the reverse osmosis treated water, was comparable to groundwater, which is traditionally considered to be the highest quality water.”
The solids recovered from wastewater are also heavily treated during recycling. The junk from the first stage is sent to local landfills, while the biosolids screened from the second and third stages are sent to anaerobic chambers where their decomposition generates that can be burned for electrical production and converted into nitrogen-rich fertilizer for use in agriculture.
New York, for example of more than 1,200 wastewater treatment plants (WWTPs) statewide. According to a 2021 report from the and is “primarily used to fuel the facilities and for the combined heat and power generation of the wastewater treatment plants.”
Non-potable water can be treated even more directly and in some cases . Wastewater, rainwater and can such as watering the lobby plants and flushing toilets after being caught and treated in a (ONWS).
Increasing pressure on water resources has led to greater water scarcity and a growing demand for alternative water sources. . “Onsite reuse of non-potable water is a solution that can help communities reclaim water, recycle it and then reuse it for non-potable water purposes.”
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On board the ISS, astronauts have even less latitude in their water use because the station is a closed system isolated 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 be put into orbit with one of its rockets — and liquid water is heavy.
While the ISS occasionally receives water in the form of 90-pound duffel bag-shaped water containers to replace what’s invariably lost to space, its inhabitants rely on the intricate web of levers and tubes seen above and below to recover any amount of moisture possible and process it into drinkability. The station’s Water Processing Assembly can produce up to 36 liters of potable water each day from the crew’s sweat, breath and urine. When it was installed in 2008, the station needed the water supply . It works in conjunction with the Urine Processor Assembly (UPA), Oxygen Generation Assembly (OGA), the Sabatier Reactor (which recombines free oxygen and hydrogen which are split back into water by the OGA), and Regenerative Environmental Control and Life Support Systems (ECLSS ) systems to maintain the station “” and . Cosmonauts in the Russian part of the ISS rely on a separate filtration system that only collects shower water and condensation and therefore require more regular water deliveries to keep their tanks topped up.
In 2017, NASA upgraded the WPA with a new reverse osmosis filter to “reduce the supply mass of the WPA Multi-filtration bed and improve the catalyst for the WPA Catalytic Reactor to lower operating temperature and pressure,” the agency announced that year . “Although the WRS [water recovery system] has performed well since work began in November 2008, several tweaks have been identified to improve overall system performance. These adjustments are intended to reduce resupply and improve overall system reliability, benefiting the ongoing ISS mission and future crewed NASA missions.
One of those improvements is the improved Brine Processor Assembly (BPA) delivered in 2021, a filter that sifts 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 safely transport crews through interplanetary space. NASA notes that the WPA delivered in 2008 was originally rated to recover 85 percent of the water in the crew’s urine, though its performance has since improved to 87 percent.
“To leave low Earth orbit and enable long-term exploration far from Earth, we need to close the water cycle,” added Caitlin Meyer, deputy project manager for Advanced Exploration Systems Life Support Systems at NASA’s Johnson Space Center in Houston. . “Current systems for recovery of urine water use distillation, which produces a brine. The [BPA] will accept that aqueous effluent and extract the remaining water.”
When the post-processed urine is then mixed with reclaimed condensation and run through the WPA again, “our total water recovery is about 93.5 percent,” said Layne Carter, International Space Station Water Subsystem Manager at Marshall, . To get to Mars safely, NASA needs a recovery rate of 98 percent or better.
But even if the ISS’s current state-of-the-art recycling technology isn’t enough to get us to Mars, it’s already having an impact on the planet. For example, in the early 2000s, the company Argonide developed a “NanoCeram” nanofiber water filtration system with funding from NASA for small businesses. The filter uses positively charged microscopic alumina fibers to remove virtually all contaminants without unduly restricting flow rate and ultimately spawning .
“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 provide,” . “The system checks the water quality 20 times per second and the most polluted water, such as shampoo rinse, is thrown overboard and replaced. The rest passes through the NanoCeram filter and is then bombarded with ultraviolet light before being recycled.” According to the Swedish Institute for Communicable Disease Control, the resulting water is cleaner than tap water.
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