Journal of Korean Society on Water Environment (한국물환경학회지)

Korean Society on Water Environment (한국물환경학회)
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Abnormal Behavior of Ordinary Heterotrophic Organism Active Biomass at Different Substrate/Microorganisms Ratios in Batch Test

회분식 실험 Substrate/Microorganisms 비에 따른 종속영양미생물의 특이거동 연구

  • Lee, Byung-Joon (Department of Environmental Engineering, Kyungpook National University) ;
  • Wentzel, M.C. (Department of Civil Engineering, University of Cape Town) ;
  • Ekama, G.A. (Department of Civil Engineering, University of Cape Town) ;
  • Min, Kyung-Sok (Department of Environmental Engineering, Kyungpook National University)
  • 이병준 (경북대학교 환경공학과) ;
  • ;
  • ;
  • 민경석 (경북대학교 환경공학과)
  • Received : 2003.10.17
  • Accepted : 2004.02.02
  • Published : 2004.05.30
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Abstract

Batch test methods have developed for a long time to measure kinetic and stoichiometric parameters which are required to perform steady state design and mathematical modelling of activated sludge processes. However, at various So/Xo ratios, abnormal behaviors of ordinary heterotrophic organism in batch tests have been reported in many researches. Thus, in this research, abnormal behaviors of heterotrophs in batch tests were investigated at various So/Xo conditions by measuring and interpreting oxygen utilization rate. As So/Xo ratio increased, the calculated values of maximum specific growth rates, ${\mu}_{H,max}$ and $K_{MP,max}$, increased. However, at a certain point of So/Xo (around 10mgCOD/mgMLAVSS), ${\mu}_{H,max}$ and $K_{MP,max}$ values started to decrease. According to this observation, three prominent behaviours of heterotrophs were identified at various So/Xo conditions. (1) At low So/Xo region (below 5 mgCOD/mgMLAVSS), the oxygen utilization rate of heterotrophs in batch tests were almost stable and consequently yielded lower maximum specific growth rate. (2) At high So/Xo region (up to 5~10 mgCOD/mgMLAVSS), oxygen utilization rate incresed sharply with time and indicated more upward curvature than the predicted OUR with conventional activated sludge model, which consists of single hetetrotrophs group. Thus, in this region, competition model of two organisms, fast-grower and slow-grower, seemed to be appropriate. (3) At extremely high So/Xo region (over 10mgCOD/mgMLAVSS), significant oxygen utilization rate was still observed even after depletion of readily biodegradable COD. This might be caused by retarded utilization of intermediates which were generated by self inhibition mechanism in the process of RBCOD uptake.

Keywords

References

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