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: Due to poor removal efficiency of refractory organic compounds, color and total phosphorous (TP) residual in the secondary effluent by the conventional advanced treatment technology, effect of ozone (O3) enhanced coagulation on the treatment of the secondary effluent was investigated in this research. The results showed that ozone could improve the pollutant removal efficiency. After ozonation, the pollutant removal rate by the coagulation and filtration process increased. O3 pre-treatment could extend the operation cycle of the variable void deep filter. In case of O3 dosage of 1.5 mg/L, PAC dosage of 4 mg/L, flocculation time of 15 min and the filter operation cycle of 16 h, the average removal rate of turbidity, COD, UV254, TP and color by the combination of O3 enhanced microflocculation and variable void deep filtration process (combination technology) was 79.0%, 46.5%, 56.6%, 30.8% and 69.2%, respectively, higher than that by the traditional combination of microflocculation and filtration process (traditional technology). In summary, the combination technology is an effective treatment technology in the tertiary treatment of the secondary effluent.Procedia Environmental Sciences. 10:555–560.
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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 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. · 5.04 Impact Factor