Aquatic environment

Effects of COD/N ratio and DO concentration on simultaneous nitrificationand denitrification in an airlift internal circulationmembrane bioreactor

MENG Qingjuan , YANG Fenglin , LIU Lifen , MENG Fangang


Received September 26, 2007,Revised November 27, 2007, Accepted , Available online

Volume 20,2008,Pages 933-939

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The effects of chemical oxygen demand and nitrogen (COD/N) ratio and dissolved oxygen concentration (DO) on simultaneous nitrification and denitrification (SND) were investigated using an airlift internal circulation membrane bioreactor (AIC-MBR) with synthetic wastewater. The results showed that the COD e ciencies were consistently greater than 90% regardless of changes in the COD/N ratio. At the COD/N ratio of 4.77 and 10.04, the system nitrogen removal e ciency became higher than 70%. However, the nitrogen removal e ciency decreased to less than 50%, as the COD/N ratio shifted to 15.11. When the operating DO concentration was maintained at 1.0 mg/L in AIC-MBR, a satisfying SND was achieved. Either low or high DO concentration could restrain SND.

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