Phosphate pollution in rivers, lakes, and other waterways has reached dangerous levels, causing algae blooms that starve fish and aquatic plants of oxygen. Meanwhile, farmers worldwide are coming to terms with a dwindling reserve of phosphate fertilizers that feed half the world’s food supply. Inspired by Chicago’s many nearby bodies of water, a Northwestern University-led team has developed a way to repeatedly remove and reuse phosphate from polluted waters. The researchers liken the development to a “Swiss Army knife” for pollution remediation as they tailor their membrane to absorb and later release other pollutants. Phosphorus underpins both the world’s food system and all life on earth. Every living organism on the planet requires it: phosphorous is in cell membranes, the scaffolding of DNA and in our skeleton. Though other key elements like oxygen and nitrogen can be found in the atmosphere, phosphorous has no analog. The small fraction of usable phosphorous comes from the Earth’s crust, which takes thousands or even millions of years to weather away. And our mines are running out.