Check out this pdf-presentation about an IFAS project, how it was designed, constructed and its performance.
FLAMMING, J. (n.y): Integrated Fixed Film Activated Sludge (IFAS) System for Additional Nitrification at the Coldwater WWTP. (= PDF Presentation ). Grand Rapids: Fishbeck, Thompson, Carr & Huber, Inc. (FTC&H) URL [Accessed: 03.06.2019]