Hier finden Sie wissenschaftliche Publikationen aus den Fraunhofer-Instituten.

Untersuchungen zur Verbesserung der Prozeßstabilität bei der Stickstoffelimination

: Böhm, E.; Hillenbrand, T.

Die Korrespondenz 40 (1993), Nr.4, S.536-554
ISSN: 0344-4635
Fraunhofer ISI ()
denitrification; Denitrifikation; nitrification; Nitrifikation; nitrogen removal; on-line-measurement; Online-Überwachung; process control; process stability; Prozeßregelung; Prozeßstabilität; Regenpufferung; Rückbelastung; Stickstoffelimination

The on-line determitation of nitrogen removal in municipal sewage treatment plants was systematically investigated. The measurements were carried out for three different plants over a period of several months. The results of the investigations into the ammononium removal (nitrification) showed that effluent ammonium peaks were primarily caused by inadequate plant operation: from directing the filtrate from waste sludge dewatering back into the influent of the plant during high loading periods (the filt r contains up to 15-25% of the total daily ammonium load on the plant); and from allowing the undiluted contents of the primary clarifiers to be flushed directly into the aerated reactors by the high hydraulic load during rainfall. In order to keep the effluent ammonium concentration below the required limits is necessary to keep the amount of influent ammonium below the removal capacity of the system. This can be accomplished by using tanks to store filtrate during sludge dewatering an d influent during r ainy periods, their contents being fed into the sewage plants during subsequent low loading periods. It was found that removal of nitrate (denitrification) was primarlily influenced by the relative concentrations between nitrogen compounds and easily degradable carbon sources. Measurements demonstrate that this relationship could vary dramatically and that unfavourable conditions often lead to high effluent NO2- and NO3-concentrations. Although it was possible to reduce effluent concentrations through vari os measures it was never fully possible to avoid effluent peaks which exceeded maximum allowable concentrations. Additional experiments designed to determine how best to increase the denitrification capacity of the plant revealed that the difference between extending the anoxic zone before aeration or adding an anoxic zone after aeration was insignificant. This is because the easily degradable carbon sources are quickly consumed in the first anoxic stage. The pap