A MODEL OF NITROGEN REMOVAL FROM WASTE-WATER IN A FIXED-BED REACTOR USING SIMULTANEOUS NITRIFICATION AND DENITRIFICATION (SND)

A model predicting the effluent nitrogen concentration of treated wast e water in an submerged fixed bed reactor using clinoptilolite clay as matrix, is presented. By this treatment oxidation of organic material , nitrification and denitrification, by three different classes of bac teria, occurs in the same environment. The occurrence of these three p rocesses within a close environment resemble too some extent the way t he processes take place in aquatic sediment, which also to some extent consists of clay. The results presented in this paper show that it is possible to simulate the simultaneous nitrification and denitrificati on (SND) processes with a model which containing 6 state-variables inc luding a coupling of the 3 processes performed by each of the bacteria l species included. The model results and the results obtained from ex perimental data are in general comparable.