Continuously Stirred Tank Reactors, engineered bacteria selector tanks from Blue Frog Systems, are placed over the influent in facultative and stabilization lagoon systems to enhance the facultative bacteria’s productivity. They can remove 90 percent of carbon and 50 percent of ammonia. The selector tank selects for indigenous biosolids-digesting bacteria that form gas-producing biofilms. The biofilms create a natural, mineral-based granular sludge bed reactor over the entire lagoon bottom. Biosolids are accumulated in winter months and digested each spring, eliminating odors and accumulation. Stabilization lagoons aerobically convert settled solids into ash, which leaves the system continuously with a small spike during seasonal turnovers. 888/237-7912; www.bluefrogsystem.com.