Effect of draft tube diameter on nitrogen removal from domestic sewage in a draft tube type reactor

1998 ◽  
Vol 38 (1) ◽  
pp. 319-326
Author(s):  
Taku Fujiwara ◽  
Iso Somiya ◽  
Hiroshi Tsuno ◽  
Yoshio Okuno
Keyword(s):  
Flow Rate ◽  
Nitrogen Removal ◽  
Draft Tube ◽  
Domestic Sewage ◽  
Tube Diameter ◽  
Continuous Treatment ◽  
Anoxic Zone ◽  
Type Reactor ◽  
Tube Type ◽  
Volumetric Loading

The effect of the ratio of draft tube diameter to reactor diameter (Di/Do) on the efficiency of nitrogen removal from domestic sewage is discussed based on liquid-circulating flow rate and continuous treatment data. More than 2.5 minutes of circulation time in the annulus part, which is required to create an anoxic zone, could be maintained under operating conditions in which air flow rate per reactor volume was 2 m3/(m3 · hr) and Di/Do was 0.19. When Di/Do was set at 0.19, the average total organic carbon (TOC), total nitrogen (TN) and dissolved nitrogen (DN) removal efficiencies were 83.2%, 72.1% and 71.6%, respectively, which were higher than those when Di/Do was at 0.26 or 0.36. From these results, it is concluded that 0.19 is the best Di/Do for nitrogen removal in a draft-tube type reactor with an effective depth of 4.0m under the treatment condition in which the BOD volumetric loading rate is in the range 0.22 to 0.46 kgBOD/(m3 · day). More than 80% nitrification and denitrification efficiencies can be achieved simultaneously when both conditions, the aerobic zone ratio being more than 0.2, and the anoxic zone ratio being more than 0.3, are satisfied.

Hydrolysis of palm stearin oil by a thermostable lipase in a draft tube-type reactor

1995 ◽  
Vol 80 (4) ◽  
pp. 340-345 ◽  
Author(s):  
Masanobu Tanigaki ◽  
Masaru Sakata ◽  
Hitoshi Takaya ◽  
Koji Mimura
Keyword(s):  
Draft Tube ◽  
Palm Stearin ◽  
Thermostable Lipase ◽  
Type Reactor ◽  
Tube Type ◽  
Hydrolysis Of

Evaluation of a novel oxidation ditch system for biological nitrogen and phosphorus removal from domestic sewage

2010 ◽  
Vol 62 (8) ◽  
pp. 1745-1754 ◽  
Author(s):  
X. Chen ◽  
T. Fujiwara ◽  
K. Ohtoshi ◽  
S. Inamori ◽  
K. Nakamachi ◽  
...  
Keyword(s):  
Nitrogen Removal ◽  
Phosphorus Removal ◽  
Domestic Sewage ◽  
Control Technology ◽  
Oxidation Ditch ◽  
Anoxic Zone ◽  
Nitrogen And Phosphorus ◽  
Nitrogen And Phosphorus Removal ◽  
Do Control ◽  
Biological Nitrogen

A novel oxidation ditch system using anaerobic tanks and innovative dual dissolved oxygen (DO) control technology is proposed for biological nitrogen and phosphorus removal from domestic sewage. A continuous bench-scale experiment running for more than 300 days was performed to evaluate the system. Monitoring and controlling the airflow and recirculation flow rate independently using DO values at two points along the ditch permitted maintenance of aerobic and anoxic zone ratios of around 0.30 and 0.50, respectively. The ability to optimize aerobic and anoxic zone ratios using the dual DO control technology meant that a total nitrogen removal efficiency of 83.2–92.9% could be maintained. This remarkable nitrogen removal performance minimized the nitrate recycle to anaerobic tanks inhibiting the phosphorus release. Hence, the total phosphorus removal efficiency was also improved and ranged within 72.6–88.0%. These results demonstrated that stabilization of the aerobic and anoxic zone ratio by dual DO control technology not only resulted in a marked improvement of nitrogen removal, but it also enhanced phosphorus removal.

Phosphorus removal under anoxic conditions in a continuous-flow A2N two-sludge process

2004 ◽  
Vol 50 (6) ◽  
pp. 37-44 ◽  
Author(s):  
Y.Y. Wang ◽  
Y.Z. Peng ◽  
T.W. Li ◽  
M. Ozaki ◽  
A. Takigawa ◽  
...  
Keyword(s):  
Flow Rate ◽  
Nitrogen Removal ◽  
Phosphorus Removal ◽  
Continuous Flow ◽  
Domestic Sewage ◽  
Organic Substrate ◽  
Optimum Conditions ◽  
Factors Affecting ◽  
Anoxic Conditions ◽  
Removal Capacity

The Anaerobic-Anoxic/Nitrification (A2N) system is a continuous-flow, two-sludge process in which Poly-P bacteria are capable of taking up phosphate under anoxic conditions using nitrate as an electron acceptor. The process is very efficient because it maximizes the utilization of organic substrate for phosphorus and nitrogen removal. An experimental lab-scale A2N system fed with domestic sewage was tested over a period of 260 days. The purpose of the experiment was to examine phosphorus removal capacity of a modified A2N two-sludge system. Factors affecting phosphorus and nitrogen removal by the A2N system were investigated. These factors were the influent COD/TN ratio, Sludge Retention Time (SRT), Bypass Sludge Flow rate (BSF) and Return Sludge Flow rate (RSF). Results indicated that optimum conditions for phosphorus and nitrogen removal were the influent COD/TN ratio around 6.49, the SRT of 14 days, and the BSF and RSF were fixed at about 26-33% of influent flow rate.

scholarly journals Application Study of a Draft-Tube-Type Reactor to Nitrification-Denitrification Process.

2000 ◽  
pp. 23-34 ◽  
Author(s):  
Taku FUJIWARA ◽  
Isao SOMIYA ◽  
Hiroshi TSUNO ◽  
Yoshio OKUNO
Keyword(s):  
Draft Tube ◽  
Application Study ◽  
Type Reactor ◽  
Tube Type ◽  
Denitrification Process

The nitrogen removal potential of predenitrification systems in sensitive coastal areas

1995 ◽  
Vol 32 (7) ◽  
pp. 135-142
Author(s):  
E. Görgün ◽  
N. Artan ◽  
D. Orhon ◽  
R. Tasli
Keyword(s):  
Water Quality ◽  
Wastewater Treatment ◽  
Nitrogen Removal ◽  
Retention Time ◽  
Treatment Process ◽  
Hydraulic Retention Time ◽  
Domestic Sewage ◽  
Coastal Areas ◽  
Careful Evaluation ◽  
Denitrification Kinetics

Effective nitrogen removal is now required to protect water quality in sensitive coastal areas. This involves a much more difficult treatment process than for conventional domestic sewage as wastewater quantity and quality exhibits severe fluctuations in touristic zones. Activated sludge is currently the most widely used wastewater treatment and may be upgraded as a predenitrification system for nitrogen removal. Interpretation of nitrification and denitrification kinetics reveal a number of useful correlations between significant parameters such as sludge age, C/N ratio, hydraulic retention time, total influent COD. Nitrogen removal potential of predenitrification may be optimized by careful evaluation of wastewater character and the kinetic correlations.

scholarly journals Effect of Air Injection on the Internal Flow Characteristics in the Draft Tube of a Francis Turbine Model

Processes ◽  
2021 ◽  
Vol 9 (7) ◽  
pp. 1182
Author(s):  
Seung-Jun Kim ◽  
Yong Cho ◽  
Jin-Hyuk Kim
Keyword(s):  
Flow Rate ◽  
Draft Tube ◽  
Pressure Fluctuations ◽  
Flow Characteristics ◽  
Internal Flow ◽  
Air Injection ◽  
Low Flow ◽  
Francis Turbine ◽  
Navier Stokes ◽  
Vortex Rope

Under low flow-rate conditions, a Francis turbine exhibits precession of a vortex rope with pressure fluctuations in the draft tube. These undesirable flow phenomena can lead to deterioration of the turbine performance as manifested by torque and power output fluctuations. In order to suppress the rope with precession and a swirl component in the tube, the use of anti-swirl fins was investigated in a previous study. However, vortex rope generation still occurred near the cone of the tube. In this study, unsteady-state Reynolds-averaged Navier–Stokes analyses were conducted with a scale-adaptive simulation shear stress transport turbulence model. This model was used to observe the effects of the injection in the draft tube on the unsteady internal flow and pressure phenomena considering both active and passive suppression methods. The air injection affected the generation and suppression of the vortex rope and swirl component depending on the flow rate of the air. In addition, an injection level of 0.5%Q led to a reduction in the maximum unsteady pressure characteristics.

scholarly journals Minimum spoutable gas flow rate in side-outlet spouted bed with inner draft-tube.

1981 ◽  
Vol 14 (6) ◽  
pp. 462-466 ◽  
Author(s):  
HIROTSUGU HATTORI ◽  
KAZUYUKI TANAKA ◽  
KUNIHIKO TAKEDA
Keyword(s):  
Flow Rate ◽  
Gas Flow ◽  
Draft Tube ◽  
Gas Flow Rate ◽  
Spouted Bed ◽  
Side Outlet

COD removal efficiency and mechanism of HMBR in high volumetric loading for ship domestic sewage treatment

2016 ◽  
Vol 74 (7) ◽  
pp. 1509-1517 ◽  
Author(s):  
Linan Zhu ◽  
Hailing He ◽  
Chunli Wang
Keyword(s):  
Removal Efficiency ◽  
Removal Rate ◽  
Sewage Treatment ◽  
Oxygen Demand ◽  
Domestic Sewage ◽  
Cod Removal ◽  
Aeration Tank ◽  
Remarkable Effect ◽  
Cod Removal Efficiency ◽  
Volumetric Loading

The hybrid membrane bioreactor (HMBR) has been applied in ship domestic sewage treatment under high volumetric loading for ship space saving. The mechanism and influence factors on the efficiency, including hydraulic retention time (HRT), dissolved oxygen (DO) of chemical oxygen demand (COD) removal were investigated. The HMBR's average COD removal rate was up to 95.13% on volumetric loading of 2.4 kgCOD/(m3•d) and the COD concentration in the effluent was 48.5 mg/L, far below the International Maritime Organization (IMO) discharge standard of 125 mg/L. DO had a more remarkable effect on the COD removal efficiency than HRT. In addition, HMBR revealed an excellent capability of resisting organics loading impact. Within the range of volumetric loading of 0.72 to 4.8 kg COD/(m3•d), the effluent COD concentration satisfied the discharge requirement of IMO. It was found that the organics degradation in the aeration tank followed the first-order reaction, with obtained kinetic parameters of vmax (2.79 d−1) and Ks (395 mg/L). The original finding of this study had shown the effectiveness of HMBR in organic contaminant degradation at high substrate concentration, which can be used as guidance in the full scale of the design, operation and maintenance of ship domestic sewage treatment devices.

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