On-line Instrumentation 2010 - WTW - #39

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For information visit www.WTW.com for a customer care center near you or inside US: call WTW 800 645 5999. Nitrogen Ni t r o g e n Me a s u r eme n t s : Ammonium · N i t r a t e · N i t r i t e Wastewater treatment processes are concerned with controlling the energy efficient removal of pollutants in the smallest possible space in the shortest possible time. Required are: • detailed knowledge of the underlying process • highest possible transparency of the process steps through corresponding measuring methods The efficient control of Nitrogen in wastewater systems is possible by making those measurements directly in the wastewater process. This not only ensures purification but above all guarantees economic operation of the entire plant. Purification processes for the removal of nitrogen from wastewater Nitrogen is found in a large variety of compounds and forms and is considered to be the ultimate “quick-change artist”. In municipal wastewater it is mainly encountered as a waste product in the form of urea, which is already converted in part to ammonium nitrogen by ammonification. In the aeration basin, the initial step of nitrification consists in oxidizing the nitrogen present in wastewater via nitrite to nitrate, for which oxygen is required. During subsequent denitrification the nitrate (NO3 –) is further converted to elemental nitrogen N2 under the absence of oxygen. This nitrogen in gas form is harmlessly released into the environment. Due to the various framework conditions and different biologically active groups of microorganisms, both methods are conducted in two fundamentally separate processes. The temporal and spatial sequence can be adapted to local conditions. 38