To find chemical engineering problems to solve, William Tarpeh uses a simple formula. “Name a wastewater, either where it comes from or something about it. Name a pollutant you want to get rid of, and then name a product you’d be interested in making,” said Tarpeh, an assistant professor of chemical engineering in the Stanford School of Engineering. This combination has fueled Tarpeh’s interests since he was a Stanford undergraduate. Now, it shapes his vision for finding innovative ways to extract value from wastewater, including new research that involves designing and refining ways to reclaim ammonia from nitrate-contaminated wastewater streams.