Development of biological filter as tertiary treatment for effective nitrogen removal: Biological filter for tertiary treatment.
ABSTRACT A biological filtration process applicable to tertiary treatment of sewage for effective nitrogen removal was developed. It consisted of a nitrification filter (Filter 1) and/or a polishing filter with anoxic and oxic parts (Filter 2). A pilot plant set at a municipal sewage treatment plant was operated for 525 d with feed of real sewage. The maximum apparent nitrification rate in Filter 1 in winter was 0.54 kg N/m3- filter-bed d. In Filter 2, the maximum denitrification capacity was 4 kg N/m3 filter-bed d) in winter. SS was stably removed and high transparency water was obtained. The target water quality (SS, BOD, and T-N5 mg/L) was accomplished in winter with the LV of 202 m/d in Filter 2, which corresponds to 0.24 h of HRT. These results proved that this process is compact, stable, convenient to install, and cost effective to build and operate as tertiary treatment to remove nitrogen effectively.
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ABSTRACT: A submerged biological aerated filter(BAF) partially aerated was used to study the removal of low concentrations of ammonia nitrogen (0.3 to 30.5 g N/m3). Four series of experiments were performed at ammonia loading rates between 6 and 903 g N /m3.d and C/N ratios from 2 to 20. The results showed that ammonia removal rates reached higher values (172 to 564 g N/m3.d) for the C/N ratio of 2 and lower values (13.6 to 34.6 g N/m3.d) for the C/N ratio of 20. Between 50 and 70% of the ammonia was removed in the upper section of the BAF where the dissolved oxygen (DO) concentration was over 2.1 g O2/m3 and the biofilm was more developed. At the bottom section of the reactor, simultaneous removal of ammonia and nitrate was observed at the DO concentrations in the range 0.4 to 0.8 g O2/m3. There was no removal of nitrogen for the loads below 15 g Nm3.d. Nitrogen cycle involves a complex set of potential biochemical pathways with reactions catalyzed by different microorganisms and the results indicate that the removal of nitrogen may not only be explained by the conventional mechanisms of nitrification/denitrification.WEF Nutrient Recovery and Management 2011 Conference; 01/2011
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ABSTRACT: The main objective of this work concerns the evaluation of the biological aerated filtration model found in GPS-X, which had never been evaluated with adequate data. This model is interesting since it integrates the physical and biological phenomena involved during filtration with a low complexity of use. The validation of the model parameters combines experimental and theoretical approaches. Experimental data were recorded at a semi-industrial pilot scale submerged biofilter operated at a tertiary nitrification stage, receiving the effluent of a medium loaded activated sludge process for municipal wastewater. Also, several protocols were regularly applied to characterize the biofilm and the nitrogen removal performances: dry density and thickness of biofilm, nitrification rates and corresponding quantity of autotrophic biomass accumulated inside the filtering media, quantity of extracted autotrophic bacteria in the backwash water, nitrification capacity along the biofilter, as well as nitrogen compounds in the effluent. For short-term dynamic conditions, a set of reliable parameter values has been used to predict nitrogen removal for different data sets. For long-term dynamic periods, the need to adapt some of the parameters from one set of data to another is demonstrated. It is shown that the hydraulic loading rate and the backwashing frequency are the main parameters responsible for these modifications.Water Research 08/2010; 44(15):4399-410. · 4.66 Impact Factor
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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-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.Bioresource Technology 09/2010; 102(2):904-12. · 4.75 Impact Factor