The role of loading rate, backwashing, water and air velocities in an up-flow nitrifying tertiary filter.
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-Nm(-3)_mediad(-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)_mediad(-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.
Civil and Water Engineering Department, Faculty of Sciences and Engineering, Pavillon Adrien-Pouliot, Laval University, Quebec, Canada G1K 7P4.
Emmanuelle
E
Vigne
Jean-Marc
JM
Choubert
Jean-Pierre
JP
Canler
Alain
A
Heduit
Kim Helleshøj
KH
Sørensen
Paul
P
Lessard
D000388:Air; D052818:Autotrophic Processes; D018533:Biomass; D019149:Bioreactors; D005374:Filtration / Q000295:instrumentation*; D058465:Nitrification / Q000502:physiology*; D009584:Nitrogen / Q000378:metabolism*; D010865:Pilot Projects; D000644:Quaternary Ammonium Compounds / Q000032:analysis; D014867:Water / Q000737:chemistry*; D018508:Water Purification / Q000295:instrumentation*
D000644:Quaternary Ammonium Compounds; D014867:Water; D009584:Nitrogen