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.
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July 01 1998
Effect of draft tube diameter on nitrogen removal from domestic sewage in a draft tube type reactor
Taku Fujiwara
;
Taku Fujiwara
*
Department of Environmental Engineering, Graduate School of Engineering, Kyoto University, Yoshida-honmachi, Sakyo-ku, Kyoto, 606-8501, Japan
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Iso Somiya
;
Iso Somiya
*
Department of Environmental Engineering, Graduate School of Engineering, Kyoto University, Yoshida-honmachi, Sakyo-ku, Kyoto, 606-8501, Japan
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Hiroshi Tsuno
;
Hiroshi Tsuno
*
Department of Environmental Engineering, Graduate School of Engineering, Kyoto University, Yoshida-honmachi, Sakyo-ku, Kyoto, 606-8501, Japan
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Yoshio Okuno
Yoshio Okuno
**
Ataka Construction and Engineering Co. Ltd, 1-9, Itachibori 2-chome, Nishi-ku, Osaka, 551-0022, Japan
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Water Sci Technol (1998) 38 (1): 319-326.
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Taku Fujiwara, Iso Somiya, Hiroshi Tsuno, Yoshio Okuno; Effect of draft tube diameter on nitrogen removal from domestic sewage in a draft tube type reactor. Water Sci Technol 1 July 1998; 38 (1): 319–326. doi: https://doi.org/10.2166/wst.1998.0076
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Taku Fujiwara, Iso Somiya, Hiroshi Tsuno, Yoshio Okuno; Effect of draft tube diameter on nitrogen removal from domestic sewage in a draft tube type reactor. Water Sci Technol 1 July 1998; 38 (1): 319–326. doi: https://doi.org/10.2166/wst.1998.0076
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