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. 01/2011; 10:555–560.
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ABSTRACT: A pilot-scale of up-flow biological aerated filter (UBAF) treating secondary effluent of municipal sewage was constructed and operated for 189 days from April 12th to October 18th. The nitrification performance of UBAF under two different air flow rates (0.6 and 1.0 m3/h) was studied. The Run I (air flow rate=0.6 m3/h) and Run II (air flow rate=1.0 m3/h) worked for 90 and 99 days respectively. During the whole operating process, the influent ammonium concentration varied within the range of 9.27-22.3 mg/L and the inflow hydraulic load was kept at 15.92 m3/m3 substratumldrd. The water temperature was 16.9-26.2degC. Air and water backwashing was conducted once per 48 h and lasted 15 min. The corresponding backwash superficial velocities were set as 50 and 15 m/h. The experiment results showed that the average ammonium removal efficiency were 64.5% in Run I and 90% in Run II. About 95% removal ammonium was converted to nitrate in the two Runs. As the air flow rate was 0.6 m3/h, the nitrite accumulation phenomenon occurred in the bottom but it was undetectable in the final effluent. In Run II, the nitrite accumulation phenomenon could not be detected thoroughly in the reactor.01/2009;
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ABSTRACT: A recent new method analyzes sequential decoding under the sole constraint that a set error probability Pe be achieved. The result is an estimate of the number of paths searched and the definition of the minimum search region in the code tree. This work extends this method to two classes of channels with memory: channels with and without intersymbol interference01/1994;