Is ammonification the rate limiting step for nitrification kinetics?

• Published in: Bioresource technology Vol. 114; pp. 117 - 125
• Main Authors: Katipoglu-Yazan, Tugce, Ubay Cokgor, Emine, Insel, Güçlü, Orhon, Derin
• Format: Journal Article
• Language: English
• Published: England Elsevier Ltd 01-06-2012
• Subjects: Ammonia - isolation & purification; Ammonia - metabolism; Ammonification; Bacteria, Aerobic - metabolism; Computer Simulation; Hydrolysis; Kinetics; Modeling; Models, Biological; Nitrification; Nitrogen - isolation & purification; Nitrogen - metabolism; Oxygen Consumption - physiology; Peptones - metabolism; Respirometry; Hydrolysis; Ammonification; Modeling; Respirometry; Nitrification
• ISSN: 0960-8524; 1873-2976
• DOI: 10.1016/j.biortech.2012.03.017

► Accumulation of soluble organic nitrogen confirms the validity of ammonification. ► Ammonification was not rate limiting for selected experimental conditions. ► Ammonia release for nitrification may be evaluated by means of hydrolysis. ► Respirometry with and without nitrification confirms the impact of hydrolysis.
This study investigated relative magnitude of hydrolysis and ammonification by separate analysis of ammonia release and nitrification mechanisms. A peptone mixture was used as substrate in two parallel experiments seeded with nitrifying biomass conducted with and without nitrification inhibitor. Results were evaluated by means of model analysis of the ammonia and the oxygen uptake rate (OUR) profiles. A dual hydrolysis mechanism with maximum rate coefficients of 6.3 and 0.5/day characterized the peptone mixture and a kinetic balance was established for the ammonia release mechanism with a corresponding ammonification rate of 0.08m3/g CODday. The experiments also showed a low soluble ammonia nitrogen generation that was rapidly depleted, confirming the existence of ammonification. These rate coefficients were verified using model calibration of the OUR profile related to simultaneous carbon removal and nitrification. Results indicated that ammonification would not be rate limiting for wastewaters such as domestic sewage, with lower hydrolysis kinetics.