As a country bordering the Rhine, Switzerland shares in the responsibility to reduce nitrogen export to the North Sea. In wastewater treatment plants, this is currently accomplished through a costly expansion of the main activated sludge system. During the 1990s, however, there were several reports of nitrogen being eliminated rather unexpectedly under certain operating conditions. It was found that this is due to a recently discovered group of bacteria, which were also found in Swiss wastewater treatment plants. Based on this discovery, process engineers have developed a new process that reliable removes nitrogen.
FUX, C. ; EGLI, K. ; MEER, J.R. ; SIEGRIST, H. (2003): The Anammox Process for Nitrogen Removal from Waste Water. PDF