In Bozeman, Montana, life centers around outdoor recreation. An afternoon of world-class fly fishing on the state’s pristine waters often follows with a refreshing visit to one of the area’s many microbreweries. The convergence of those two pastimes took an innovative twist when a group of engineers asked: What if the carbon-rich byproduct of brewing beer could be used as a cost-effective way for the city to reduce nitrogen in its wastewater? That idea led to a pilot study with the potential to benefit communities throughout the world.