A New Thiele＇s Modulus for the Monod Biofilm Model

作     者：方元祥 GOVIND Rakesh FANG Yuanxiang;GOVIND Rakesh

作者机构：National Risk Management and Research Laboratory U.S. Environmental Protection Agency 26 W. Martin Luther King Dr. Cincinnati OH45268 USA Department of Chemical and Materials Engineering University of Cincinnati Cincinnati OH45221 USA 

出 版 物：《Chinese Journal of Chemical Engineering》 (中国化学工程学报（英文版）)

年 卷 期：2008年第16卷第2期

页      面：277-286页

核心收录：

学科分类：07[理学] 0703[理学-化学] 

主　　题：Monod biofilm kinetic model effectiveness factor Thieles modulus generalized concentration profiles 

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 indi- cated 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 identifica- tion were based on the values of φF and φG, the limiting processes for biomass growth, and substrate conversion. Developed from φF, a new parameter ψ was 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.