The role of loading rate, backwashing, water and air velocities in an up-flow nitrifying tertiary filter |
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Authors: | Vigne Emmanuelle Choubert Jean-Marc Canler Jean-Pierre Heduit Alain Sørensen Kim Helleshøj Lessard Paul |
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Institution: | a Civil and Water Engineering Department, Faculty of Sciences and Engineering, Pavillon Adrien-Pouliot, Laval University, Quebec (Quebec), Canada G1K 7P4 b CEMAGREF, UR MALY, 3 bis quai Chauveau, F-69336 Lyon, France c CEMAGREF, UR HBAN, parc de Tourvoie - BP 44, F-92163 Antony, France d VEOLIA EAU, Immeuble Giovanni Battista B, 1 rue Giovanni Battista Pirelli, 94410 Saint-Maurice Cedex, France |
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Abstract: | The vertical distribution of nitrification performances in an up-flow biological aerated filter operated at tertiary nitrification stage is evaluated in this paper. Experimental data were collected from a semi-industrial pilot-plant under various operating conditions. The actual and the maximum nitrification rates were measured at different levels inside the up-flow biofilter. A nitrogen loading rate higher than 1.0 kg NH4-N m−3_media d−1 is necessary to obtain nitrification activity over all the height of the biofilter. The increase in water and air velocities from 6 to 10 m h−1 and 10 to 20 m h−1 has increased the nitrification rate by 80% and 20% respectively. Backwashing decreases the maximum nitrification rate in the media by only 3-14%. The nitrification rate measured at a level of 0.5 m above the bottom of the filter is four times higher than the applied daily average volumetric nitrogen loading rate up to 1.5 kg NH4-N m−3_media d−1. Finally, it is shown that 58% of the available nitrification activity is mobilized in steady-state conditions while up to 100% is used under inflow-rate increase. |
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Keywords: | Nitrification rate Submerged biofilter Nitrogen loading rate Water and air velocity Backwash water |
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