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Investigation of nitrogen removal in a cascaded membrane bioreactor.

Two different plants in different scales were compared. The main characteristic of the plants is the division of the nitrification volume into separate chambers. To gain more information about the internal conversion processes, concentration profiles of COD, NO3-N and NH4-N along the pathway of the waste water were measured. Moreover, the effect of different plant configurations and different operation conditions involving the internal circulation streams on the biological conversion processes were studied. Except for some temporary operation problems, the treatment performance of the plants was very stable and on a high level. There was a high correspondence between the plants. Operation without internal recirculation leads to lower effluent concentrations of ammonium. Beside this, operation of several nitrification chambers instead of only one chamber results in lower ammonium effluent concentrations.