Water recycling technologies developed for space are helping an arid American West

wWhether you live in the rapidly 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 wreak havoc on Western aquifers and as humanity reaches further into the solar system, the water supply challenges we face today will only increase. Some of NASA’s cutting-edge water recycling research in orbit is returning to Earth.

On earth
In California, for example, from homes and businesses across the state, from storm drains and roof-connected runoff, it makes its way through more than 100,000 miles of sewer lines where it — except — eventually ends up in one of 900 water treatment plants state waste. How water is treated depends on whether it is intended for human consumption or for non-potable uses such as agricultural irrigation, wetland improvement and groundwater replenishment.

adopts a multi-stage approach to the recovery of its potable wastewater. Large solids are first filtered from the incoming fluids using mechanical screens in the treatment plant shells. From there, the wastewater flows into a tailing tank where most of the remaining solids, deposited in the anaerobic digesters after sinking to the bottom of the pool, are removed. The water is then sent to secondary processing 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 any solid residues are removed. By 2035, while Aurora, Colorado, and Atlanta, Georgia have already begun increasing their supplies of drinking water with potable reuse.

“There are further benefits beyond a secure water supply. If you’re not relying on imported water, that means there’s more water for ecosystems in Northern California or Colorado,” said Stanford professor William Mitch, in . “You’re cleaning up wastewater, and therefore you’re not dumping sewage and potential contaminants on California beaches.”

Wastewater treatment plants in California face a number of challenges, he notes, including aging infrastructure; contamination from improperly disposed pharmaceuticals and pesticide runoff; population demands combined with reduced flows due to drought induced by climate change. However, their ability to provide pristine water actually surpasses nature.

“We expected that reused drinking water would be cleaner, in some cases, than conventional drinking water due to the fact that much more extensive treatment is conducted for it,” Mitch said in an October study on . ‘But we were surprised that in some cases the quality of the reuse water, particularly reverse osmosis treated water, was comparable to 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 the anaerobic chambers where their decomposition generates which can be burned for electricity production and converted into nitrogen-rich fertilizer for agricultural use.

New York, for example, from its more than 1,200 wastewater treatment plants (WWTPs) across the state. However, fewer than a tenth of plants (116 specifically) actually use that sludge to produce biogas, according to a 2021 report from , and it’s “used primarily to power facilities and for combined heat and power generation of WWTPs.”

Non-potable water can be treated even more directly and, in some cases, . Sewage, rainwater and can water the atrium plants and flush toilets after being captured and treated in an (ONWS).

EPA

“Increasing pressures on water resources have led to greater water scarcity and a growing demand for alternative water sources,” the . “On-site reuse of non-potable water is a solution that can help communities recover, recycle, and then reuse water for non-potable purposes.”

In orbit

Aboard the ISS, astronauts have even less leeway in using water because the station is an isolated closed-loop system in space. Also because SpaceX charges $2,500 a pound of cargo (after the first 440 pounds, for which it charges $1.1 million) to send one of its rockets into orbit — and liquid water is heavy.

ISS water system
ESA

While the ISS gets the occasional shipment of water in the form of 90-pound duffel-shaped emergency water containers to replace what’s invariably lost to space, its inhabitants rely on the complicated web of levers and pipes you see above and below to recover every possible drop of humidity and transform it into potable water. The station’s Water Processing Assembly can produce up to 36 gallons of potable water each day from the crew’s sweat, breath, and urine. When it was installed in 2008, the station’s water delivery needs. It works in conjunction with the Urine Processor Assembly (UPA), the Oxygen Generation Assembly (OGA), the Sabatier reactor (which recombines the free oxygen and hydrogen cleaved from the OGA into water) and the regenerative environmental control systems and life support systems (ECLSS) to maintain station “” and . Cosmonauts in the Russian segment of the ISS rely on a separate filtration system that collects only shower runoff and condensate and therefore require more regular water deliveries to keep their tanks full.

ISS 2 water system
ESA

In 2017, NASA upgraded the WPA with a new reverse osmosis filter to “reduce WPA multi-filtration bed replenishment mass and improve the catalyst for the WPA catalytic reactor to reduce operating temperature and pressure,” it announced. the agency that year. “Although the WRS [water recovery system] has been working well since it began operations in November 2008, several changes have been identified to improve overall system performance. These changes are intended to reduce supplies and improve overall system reliability, which is beneficial to the current ISS mission and future NASA crewed missions.”

One such improvement is the updated Brine Processor Assembly (BPA) delivered in 2021, a filter that filters more salt from astronaut urine to produce more reclaimed water than its predecessor. But there is still a long way to go before crews can be safely transported through interplanetary space. NASA notes that the WPA that was delivered in 2008 was originally rated to recover 85 percent of the water in crew urine, though its performance has since improved to 87 percent.

BPA diagram
NASA

“To leave low-Earth orbit and enable long-duration exploration far from Earth, we need to close the water loop,” added Caitlin Meyer, deputy project manager for Advanced Exploration Systems Life Support Systems at the Johnson Space Center of the NASA in Houston. “Current urine water recovery systems use distillation, which produces a brine. The [BPA] it will accept that water-containing effluent and extract the remaining water.

When the post-treated urine is then mixed with the recovered condensate and flows back through the WPA, “our overall water recovery is about 93.5 percent,” Layne Carter, International Space Station Water Subsystem Manager at Marshall, . To get to Mars safely, NASA calculates they need a recovery rate of 98% or better.

But even if the ISS’s current cutting-edge recycling technology isn’t enough to get us to Mars, it’s already having a planetary impact. For example, in the early 2000s the Argonide company developed a “NanoCeram” nanofiber water filtration system with financial support from NASA for small businesses. The filter uses microscopic, positively charged alumina fibers to remove virtually all contaminants without excessively limiting the flow rate, ultimately causing spawning.

“The shower starts with less than a gallon of water and circulates it at a rate of three to four gallons per minute, a flow greater than that provided by most conventional showers,” . “The system checks the water quality 20 times a second and the most polluted water, such as shampoo, is drained and replaced. The rest passes through the NanoCeram filter and is then 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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