Ammonia removal ranks as a major new issue for many wastewater treatment managers particularly those whose plants discharge into warm-water streams with seasonal low flows. The U.S. Environmental Protection Agency’s new approach to implementing water quality-based ammonia limits has fueled a fervent interest in cost-effective nitrification. A pilot study completed in 1988 at the Central Valley Water Reclamation Facility in Salt Lake City, Utah has demonstrated that nitrifying trickling filters (NTFs) may be the wave of the future as far as ammonia removal is concerned.