Effects of COD/N ratio and DO concentration on simultaneous nitrifcation and denitrifcation in an airlift internal circulation membrane bioreactor

Key Laboratory of Industrial Ecology and Environmental Engineering, MOE, School of Environmental and Biological Science and Technology, Dalian University of Technology, Dalian 116024, China.
Journal of Environmental Sciences (Impact Factor: 2). 02/2008; 20(8):933-9. DOI: 10.1016/S1001-0742(08)62189-0
Source: PubMed


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 efficiencies 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 efficiency became higher than 70%. However, the nitrogen removal efficiency 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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    • "e two MBR processes can achieve SND with high performance in a single bioreactor ( Holakoo et al . , 2005 ; Zhang et al . , 2006a ) . In addition , inserting baffles into a normal submerged MBR can generate one high DO zone and one low DO zone in a single bioreactor , which are also ex - pected to achieve high rate of SND ( Kimura et al . , 2008 ; Meng et al . , 2008 ) . We can notice that most of recent investigations attempted to create aerobic zone and anaerobic or anoxic zone either at macroscale level ( i . e . , in a single bioreactor ) or at microscale level ( i . e . , within one sludge floc ) . These efforts also attempted to acclimatize the bacteria responsible for ni - trification and den"
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