in novel bacteria and system designs. Huang achieved significant ammonia removal in an attached growth process with ciliated columns packed with granular sulfur where the denitrifying bacteria used the sulfur as the electron donor and nitrate as the electron acceptor. Another well established pathway is via autotrophic denitrifying bacteria in the process termed the Anammox process. It is typically used for high ammonia strength wastewater. Notes References Hwang, Y., Kim, C., Choo, I. "Simultaneous Nitrification/Denitrification in a Single Reactor using Ciliated Columns Packed with Granular Sulfur." Water Quality Research Journal of Canada. 40: 91–96, 2005 Nielson, P.H., Thompson, T.R. & Nielson, J.L. "Bacterial Composition of Activated Sludge – Importance for Floc and Sludge Properties." Water Science and Technology, 49: 51–58, 2004. Tchobanoglous, G., Burton, F. & Stensel, H. Wastewater Engineering. 4th Ed. Mc Graw Hill, Inc. New York, 2003. Nitrogen cycle Water treatment