Continuous nitrifying granular sludge bioreactor: Influence of aeration and ammonium loading rate |
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| Affiliation: | 1. Biotechnology Research Center (BRC), Sahand University of Technology, Tabriz 51335-1996, Iran;2. Department of Chemical Engineering, Sahand University of Technology, Tabriz 51335-1996, Iran;3. Environmental Engineering Research Center (EERC), Sahand University of Technology, Tabriz 51335-1996, Iran;1. Chemical Engineering Faculty, Sahand University of Technology, Tabriz 51335-1996, Iran;2. Stem Cell and Tissue Engineering Research Laboratory, Sahand University of Technology, Tabriz 51335-1996, Iran;3. Hematology and Oncology Research Center, Tabriz University of Medical Sciences, Tabriz 51666-16471, Iran;4. Blood Transfusion Research Center, High Institute for Research and Education in Transfusion Medicine, Tabriz 51666-16471, Iran;1. Department of Chemical Engineering, Jadavpur University, Kolkata 700032, India;2. School of Water Resources Engineering, Jadavpur University, Jadavpur, Kolkata 700032, India;1. Department of Chemistry, Queen’s University, Kingston, ON K7L 3N6, Canada;2. Water Science and Technology Directorate, Environment and Climate Change Canada, 867 Lakeshore Road, Burlington, ON L7S 1A1, Canada |
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| Abstract: | Granulation of nitrifying bacteria was investigated in a continuous bubble column bioreactor. Then, the combined effect of aeration and ammonium loading rates on dissolved oxygen (DO) concentration as well as nitrification process was evaluated in the system using an experimental design technique. After 120 days, stable nitrifying granules with average diameter of 1.4 mm and settling velocities of 55 m/h were obtained. The influence of increasing ammonium loading rate (ALR) was found to be more significant than decreasing aeration rate on the reduction of DO concentration inside the nitrifying bioreactor. The system could handle the ALR values of 0.48–1.92 gNH4+-N/L d with the ammonium removal efficiency from 65% to nearly 100% at the tested airflow rates of 2.5 and 4.5 L/min. At the low aeration, the complete ammonium conversion to nitrate was replaced with nitrite when the ALR increased to 1.44 gNH4+-N/L d. At the high aeration, however, almost complete nitrification was achieved except the high ALR in which the nitrite accumulation was observed up to 38%. The study demonstrated that the continuous bioreactor had a considerable performance for obtaining stable nitrifying granules to have nitrite accumulation under control with changing the ratio of aeration rate and ALR. |
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| Keywords: | Nitrifying granules Nitrite accumulation Ammonium loading rate Aeration rate Continuous bubble column bioreactor |
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