Comparative study of nitrification performances of immobilized cell fluidized bed reactor and contact oxidation biofilm reactor in treating high strength ammonia wastewater

A laboratory-scale fluidized-bed reactor with an external aeration loop was used for nitrification of high-strength ammonium wastewater (up to 500 mg NH4-N/L). The results demonstrated that the system is capable of handling ammonium removal rates of up to 2.5 kg NH4-N/m3·d, while removal efficiencies were as high as 98% and independent of the applied ammonium loading rates. Ammonium loading rates higher than 2.5 kg NH4-N/m3·d resulted in decreased ammonium removal efficiency. The data show that near complete ammonium removal occurred at DO concentrations as low as 0.3-0.5 mg/L. However, the nitrite-nitrogen fraction in the effluent increased from 3.5% to 23.2% when the DO dropped from 1.0 mg/L to approximately 0.4 mg/L, respectively. The high specific removal rates in this system are one order of magnitude higher than that of suspended-growth systems. This can reduce the supplementary reactor volumes required for nitrification to less than 10% of that needed in conventional activated sludge systems. These results clearly indicate the potential economic gains that could be achieved through implementation of this technology.

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Treating high-strength nitrate wastewater by three biological processes

Water Science & Technology ◽

10.2166/wst.1999.0672 ◽

1999 ◽

Vol 39 (10-11) ◽

pp. 311-314 ◽

Cited By ~ 2

Author(s):

Shing-Der Chen ◽

Chiu-Yang Chen ◽

Yu-Feng Wang

Keyword(s):

Immobilized Cells ◽

High Strength ◽

Fluidized Bed Reactor ◽

Operating Conditions ◽

Biological Processes ◽

Immobilized Cell ◽

Different Types ◽

Activated Sludge Reactor ◽

Cell Reactor ◽

The One

Three different types of bioreactors including an activated sludge reactor (ASR), a biologically mediated activated carbon fluidized bed reactor (BAFBR) and an upflow immobilized cell reactor (UICR) were studied. The results suggest that the carbon-nitrogen equivalent (CNE) ratio (in terms of CODN) when using ASR to treat the wastewater will decrease as the sludge age increases while it will increase slightly as the influent concentration increases. The CNE ratios for BAFBR and UICR are 3.67 and 3.61 respectively. For the test between the two different growth types, the CNE ratio of suspended growth will be lower than the one of attached growth. The alkalinity-nitrogen equivalent (ANE) ratio (in term of Alk/N) for ASR is 3.78, for BAFBR it is 3.54, and for UICR it is 3.63. These ANE ratios are comparable with the theoretical value of 3.57. Under different operating conditions, slight changes of microorganisms are detected in Scanning Electron Microscope observation, but the dominant species, bacillus group, showed superior growth in all cases. Tests with the immobilized cells, biofilms will grow on the surface of them at the end of operation and the subsequent biochemical reactions will concentrate on the outer layer of biofilms.

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