SCI和EI收录∣中国化工学会会刊

›› 2008, Vol. 16 ›› Issue (2): 277-286.

• • 上一篇    下一篇

A New Thiele's Modulus for the Monod Biofilm Model

方元祥1, GOVIND Rakesh2   

  1. 1. National Risk Management and Research Laboratory, U.S.Environmental Protection Agency, 26 W.Martin Lu-ther King Dr.Cincinnati, OH45268, USA;
    2. Department of Chemical and Materials Engineering, University of Cincinnati, Cincinnati, OH45221, USA
  • 收稿日期:2007-06-11 修回日期:2007-11-19 出版日期:2008-04-28 发布日期:2008-04-28
  • 通讯作者: FANG Yuanxiang,E-mail:fangjames@hotmail.com

A New Thiele's Modulus for the Monod Biofilm Model

FANG Yuanxiang1, GOVIND Rakesh2   

  1. 1. National Risk Management and Research Laboratory, U.S.Environmental Protection Agency, 26 W.Martin Lu-ther King Dr.Cincinnati, OH45268, USA;
    2. Department of Chemical and Materials Engineering, University of Cincinnati, Cincinnati, OH45221, USA
  • Received:2007-06-11 Revised:2007-11-19 Online:2008-04-28 Published:2008-04-28

摘要: A new Thiele's modulus,φF,was developed to provide a gradual transition between zero and the first order of kinetics,and to accurately calculate the mass transfer flux and the effectiveness factor for the Monod biofilm.Values of the effectiveness factor,calculated using the new Thiele's modulus,were compared with those obtained from numerical solutions and from other published moduli and empirical formulae.The comparison indicated that the new Thiele's modulus was the best modulus for the Monod biofilm model.In addition,another Thiele's modulus,φG,was developed for a Monod biofilm,covered with an external water layer.The overall effectiveness factor can also be calculated by using both moduli φF and φG.The criteria that were proposed for identification were based on the values of φF andφG,the limiting processes for biomass growth,and substrate conversion. Developed from φF,a new parameterψwas related uniquely to such features as the depth and shallowness of the generalized substrate concentration profiles inside a Monod biofilm.Criteria were developed to identify the types of concentration distribution inside a Monod biofilm.These methods were used to estimate the substrate flux and the concentration distribution of the biofilms defined in the first benchmark problem(BM1),by a task group of the International Water Association on Biofilm Modeling.

关键词: Monod biofilm, kinetic model, effectiveness factor, Thieles modulus, generalized concentration profiles

Abstract: A new Thiele's modulus,φF,was developed to provide a gradual transition between zero and the first order of kinetics,and to accurately calculate the mass transfer flux and the effectiveness factor for the Monod biofilm.Values of the effectiveness factor,calculated using the new Thiele's modulus,were compared with those obtained from numerical solutions and from other published moduli and empirical formulae.The comparison indicated that the new Thiele's modulus was the best modulus for the Monod biofilm model.In addition,another Thiele's modulus,φG,was developed for a Monod biofilm,covered with an external water layer.The overall effectiveness factor can also be calculated by using both moduli φF and φG.The criteria that were proposed for identification were based on the values of φF andφG,the limiting processes for biomass growth,and substrate conversion. Developed from φF,a new parameterψwas related uniquely to such features as the depth and shallowness of the generalized substrate concentration profiles inside a Monod biofilm.Criteria were developed to identify the types of concentration distribution inside a Monod biofilm.These methods were used to estimate the substrate flux and the concentration distribution of the biofilms defined in the first benchmark problem(BM1),by a task group of the International Water Association on Biofilm Modeling.

Key words: Monod biofilm, kinetic model, effectiveness factor, Thieles modulus, generalized concentration profiles