Dissolved organic nitrogen behaviour during denitrification with suspended and attached biomass

Dissertação para obtenção do Grau de Mestre em Engenharia do Ambiente, perfil Engenharia Sanitária

In a wastewater treatment plant (WWTP) dissolved organic nitrogen (DON) represents an important fraction of N in the final effluent. The purpose of this study was to analyze DON changes along denitrification with suspended and attached biomass. Denitrification batch experiments were carried out with activated sludge and biological (kaldnes) carriers. In the batch tests with kaldnes it was used two different mixing velocities to evaluate its influence in DON concentrations. For the batch tests were evaluated COD and DOC concentrations. A comparison of the fate of DON during a denitrification process and the original effluent DON concentration was made. DON determinations oscillate in a range from 0.1 to 1.9 mg/l during a denitrification test. The comparison between DON determinations and the original effluent confirm that DON has a significant portion (about 20%) of the effluent N. The results obtained indicate that DON has a constant behavior along the denitrification process.