Effect of water velocity on ammonium and nitrite removal in pilot scale fixed bed biofilters |
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| Affiliation: | 1. Sokoine University of Agriculture, Department of Animal, Aquaculture and Range Sciences, P.O Box, 3004, Morogoro, Tanzania;2. Mwalimu Julius K. Nyerere University of Agriculture and Technology, College of Fisheries and Aquatic Sciences, P.O Box 976, Musoma, Tanzania;3. Technical University of Denmark, DTU Aqua, Section for Aquaculture, The North Sea Research Centre, P.O. Box 101, DK-9850, Hirtshals, Denmark;4. Technical University of Denmark, Department of Environmental Engineering, DTU Environment, Bygningstorvet, Build. 115, DK-2800, Kgs. Lyngby, Denmark;1. ADS Environmental Services Sdn. Bhd., Lot 1-1 (Mc No.2), Likas, 88400, Kota Kinabalu, Sabah, Malaysia;2. Department of Physics and Physical Oceanography Memorial University of Newfoundland, St. John''s, NL, A1B 3X7, Canada;3. Northwest Atlantic Fisheries Centre, 80 East White Hills, St John''s, Newfoundland and Labrador, A1C 5X1, Canada;1. Department of Environmental Technology and Management, Faculty of Environment, Kasetsart University, Bangkok, 10900, Thailand;2. Department of Veterinary Technology, Faculty of Veterinary Technology, Kasetsart University, Bangkok, 10900, Thailand;3. Integrated Biorefinery Excellent Center (IBC), School of Energy and Environment, University of Phayao, Phayao, 56000, Thailand;1. Department of Biological and Agricultural Engineering, Louisiana State University and LSU Agricultural Center, Baton Rouge, LA 70803, USA;2. Aquatic Germplasm and Genetic Resources Center, School of Renewable Natural Resources, Louisiana State University Agricultural Center, Baton Rouge, LA 70820, USA;1. Technical University of Denmark, DTU Aqua, Section for Aquaculture, The North Sea Research Centre, P.O. Box 101, DK-9850 Hirtshals, Denmark;1. Graduate School of Fisheries Sciences, Hokkaido University, 3-1-1, Minato-cho, Hakodate, Hokkaido 041-8611, Japan;2. Faculty of Fisheries Sciences, Hokkaido University, 3-1-1, Minato-cho, Hakodate, Hokkaido 041-8611, Japan;3. Faculty of Agriculture, Kindai University, 3327-204, Naka-machi, Nara 631-8505, Japan;4. Faculty of Science and Engineering, Kindai University, 3-4-1, Kowakae, Higashi-Osaka, Osaka 577-8502, Japan;5. Aquaculture Research Institute, Kindai University, 3153, Shirahama-cho, Nishimuro-gun, Wakayama 649-2211, Japan;6. Hatchery Aquaculture Technology and Production Center, Kindai University, 195, Keten, Setouchi-cho, Ohshima-gun, Kagoshima 894-1853, Japan;7. Furuno Electric Co., Ltd., 9-52, Ashihara-cho, Nishinomiya, Hyogo 662-8580, Japan;1. Escuela de Ciencias del Mar, Pontificia Universidad Católica de Valparaíso (ECM-PUCV), Avenida Altamirano 1480, CP 2340000, Valparaíso, Chile;2. Programa de Pós Graduação em Aquicultura, Universidade Federal do Rio Grande (FURG), Rua do Hotel, n°2, Cassino, 96210-030, Rio Grande, RS, Brazil |
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| Abstract: | The effect of water velocity on nitrification rates in fixed bed biofilters was investigated in three freshwater pilot scale RAS with rainbow trout. Removal of total ammonia nitrogen (TAN) and nitrite-nitrogen were assessed by NH4Cl spikes and tested at four different water velocities in the biofilters (1.4, 5.4, 10.8 and 16.2 m h−1) under identical conditions. Water velocities below 10.8 m h−1 significantly reduced TAN- and nitrite removal rates. The surface specific TAN removal rates correlated with the TAN concentrations at the water velocities 10.8 and 16.2 m h−1, and the first order surface removal rate constant was estimated at 0.45 m h−1. However, no correlations between TAN removal and TAN concentrations were found at the lowest velocities. Up to five-fold elevated nitrite levels were found in the RAS when biofilters were operated at 1.4 m h−1 compared to the trials at other water velocities, substantiating the significant effect of water velocity on both nitrification processes. The importance of biofilter hydraulics documented in this pilot scale RAS probably have implications for design and operation in larger scale RAS. |
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| Keywords: | Nitrification Biofiltration Water velocity Hydraulics |
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