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KMID : 1024520120210121455
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Journal of the Environmental Sciences
2012 Volume.21 No. 12 p.1455 ~ p.1462
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Correlationship of Vertical Distribution for Ammonia Ion, Nitrate Ion and Nitrifying Bacteria in a Fixed Bed Nitrifying Biofilm
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Choi Gi-Chung
Byun Im-Gyu
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Abstract
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The vertical distributions of nitrifying bacteria in aerobic fixed biofilm were investigated to evaluate the
relationship between nitrification performance and microbial community at different HRT. Fluorescent in situ
hybridization (FISH) and portable ion selective microelectrode system were adopted to analyze microbial
communities and ions profiles according to the biofilm depth. Cilia media packed MLE (Modified
Ludzack-Ettinger) like reactor composed of anoxic, aerobic Ⅰ/Ⅱ was operated with synthetic wastewater
having COD 200 mg/L and NH4+-N 40 mg/L at HRT of 6 hrs and 4 hrs. Total biofilm thickness of aerobic Ⅰ,
Ⅱ reactor at 4 hrs condition was over two times than that of 6 hrs condition due to the sufficient substrate
supply at 4 hrs condition (6 hrs; aerobic Ⅰ 380 ㎛ and Ⅱ 400 ㎛, 4 hrs; aerobic Ⅰ 830 ㎛ and Ⅱ 1040 ㎛). As
deepen the biofilm detection point, the ratio of ammonia oxidizing bacteria (AOB) was decreased while the
ratio of nitrite oxidizing bacteria (NOB) was maintained similar distribution at both HRT condition. The ratio of
AOB was higher at 4 hrs than 6 hrs condition and NH4+-N removal efficiency was also higher at 4 hrs with
89.2% than 65.4% of 6 hrs. However, the ratio of NOB was decreased when HRT was reduced from 6 hrs to 4
hrs and NO2--N accumulation was observed at 4 hrs condition. Therefore, it is considered that insufficient HRT
condition could supply sufficient substrate and enrichment of AOB in all depth of fixed biofilm but cause
decrease of NOB and nitrite accumulation.
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KEYWORD
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Biofilm, Microelectrode, Fluorescent in situ hybridization (FISH), Ammonia oxidizing bacteria, Nitrite oxidizing bacteria, Nitrite accumulation
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