Detecting Inhibition of Nitrification – Experience Report

Handling Interferences in Complex Matrices for Metals, Nutrients, and COD
Oral Presentation

Prepared by C. Prokisch, A. Leitzke
MACHEREY-NAGEL, MACHEREY-NAGEL, Neumann-Neander-Str. 6-8, Dueren, NRW, 52355, Germany

Contact Information:; +492421969166


“Nutrient pollution is one of America´s most widespread, costly and challenging environmental problems” (as seen on In Europe, nutrient removal is a well-established process on nearly all sewage plants. Often, the traditional process with nitrification / denitrification via the Nitrate pathway is used.
In the nitrification step, Ammonia is first oxidized to Nitrite and then further oxidized to Nitrate. Both steps, Ammonia-Oxidation and Nitrite-Oxidation can be inhibited by substances in the in-flow of the plant. Such inhibition significantly reduces the efficiency of this cleaning step and leads to too higher concentration of N-compounds in the out-flow.
A-Tox and N-Tox are easy-to-use amperometric test kits using commercially available bacteria. They allow to detect such inhibitions in less than 15 minutes and therefore enable immediate quick reaction to bring the process back to full capacity.
MACHEREY-NAGEL is a German company founded in 1911 that is the major competitor of HACH in Germany and large parts of Europe. This competition led to a comparably very modern installation base for instruments that provides huge benefits for the end-user. In the US, MACHEREY-NAGEL water analysis has so far not been available.