Water recycling technologies developed for space are helping a parched American west

Whether you live in the rapidly drying American West or are aboard the International Space Station for a six-month stint, having enough water to live on is a constant concern. As climate change continues to play havoc on the West’s aquifers, and as humanity pushes further into the solar system, the potable supply challenges we face today will only grow. In their efforts to ensure humanity has enough to drink, some of NASA’s cutting-edge in-orbit water recycling research is coming back down to Earth. On Earth In California, for example, the four billion gallons of wastewater generated daily from the state’s homes and businesses, storm drain and roof-connected runoff, makes its way through more than 100,000 miles of sewer lines where it — barring obstructionist fatbergs — eventually ends up at one of the state’s 900 wastewater treatment plants. How that water is processed depends on whether it’s destined for human consumption or non-potable uses like agricultural irrigation, wetland enhancement and groundwater replenishment. The city of Los Angeles takes a multi-step approach to reclaiming its potable wastewater. Large solids are first strained from incoming fluids using mechanical screens at the treatment plant’s headworks. From there, the wastewater flows into a settling tank where most of the remaining solids are removed — sludged off to anaerobic digesters after sinking 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 clarifying, tank. Finally it’s filtered through a tertiary cleaning stage of cationic polymer filters where any remaining solids are removed. By 2035, LA plans to recycle all of its wastewater for potable reuse while Aurora, Colorado, and Atlanta, Georgia, have both already begun augmenting their drinking water supplies with potable reuse. “There are additional benefits beyond a secure water supply. If you’re not relying on importing water, that means there’s more water for ecosystems in northern California or Colorado,” Stanford professor William Mitch, said in a recent Stanford Engineering post. “You’re cleaning up the wastewater, and therefore you’re not discharging wastewater and potential contaminants to California’s beaches.” Wastewater treatment plants in California face a number of challenges, the Water Education Foundation notes, 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 deliver pristine water actually outperforms nature. “We expected that potable reuse waters would be cleaner, in some cases, than conventional drinking water due to the fact that much more extensive treatment is conducted for them,” Mitch argued in an October study in Nature Sustainability. “But we were surprised that in some cases the quality of the reuse water, particularly the reverse-osmosis-treated waters, was comparable to groundwater, which is traditionally considered the highest quality water.” The solids pulled from wastewater are also heavily treated during recycling. The junk from the first stage is sent to local landfills, while the biological solids strained from the second and third stages are sent to anaerobic chambers where their decomposition generates biogas that can be burned for electrical production and converted to nitrogen-rich fertilizer for agricultural use. New York, for example, produces 22,746 tons of wastewater sludge per day from its 1,200-plus statewide wastewater treatment plants (WWTPs). However, less than a tenth of plants (116 specifically) actually use that sludge to produce biogas, per a 2021 report from the Rockefeller Institute for Government, and is “mainly utilized to fuel the facilities and for the combined heat and power generation of the WWTPs.” Non-potable water can be treated even more directly and, in some cases, on-site. Wastewater, rainwater and greywater can all be reused for non-drinking uses like water the lobby plants and flushing toilets after being captured and treated in an Onsite non-potable water reuse system (ONWS). EPA “Increasing pressures on water resources have led to greater water scarcity and a growing demand for alternative water sources,” the Environmental Protection Agency points out. “Onsite non-potable water reuse is one solution that can help communities reclaim, recycle, and then reuse water for non-drinking water purposes.” In Orbit Aboard the ISS, astronauts have even less leeway in their water use on account of the station being a closed-loop 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 send into orbit on one of its rockets — and liquid water is heavy. ESA While the ISS does get the occasional shipment of water in the form of 90-pound duffle bag-shaped Contingency Water Containers to replace what’s invariably lost to space, its inhabitants rely on the complicated web of levers and tubes you see above and below to reclaim every dram of moisture possible and process it into potability. The station’s Water Processing Assembly can produce up to 36 gallons of drinkable water every day from the crew’s sweat, breath and urine. When it was installed in 2008, the station’s water delivery needs dropped by around 1,600 gallons, weighing 15,960 pounds. It works in conjunction with the Urine Processor Assembly (UPA), Oxygen Generation Assembly (OGA), Sabatier reactor (which recombines free oxygen and hydrogen split by the OGA back into water) and Regenerative Environmental Control and Life Support Systems (ECLSS) systems to maintain the station’s “water balance” and supply American astronauts with a minimum of 2.5 liters of water each day. Cosmonauts in 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 topped off. ESA In 2017, NASA upgraded the WPA with a new reverse-osmosis filter in order to, “reduce the resupply mass of the WPA Multi-filtration Bed and improved catalyst for the WPA Catalytic Reactor to reduce the operational temperature and pressure,” the agency announced that year. “Though the WRS [water recovery system] has performed well since operations began in November 2008, several modifications have been identified to

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