Brockmann D, Rosenwinkel K-H, Morgenroth E
Institute for Water Quality and Waste Management, Leibniz Universität Hannover, Hanover, Germany.
Biotechnol Bioeng. 2008 Oct 15;101(3):497-514. doi: 10.1002/bit.21932.
Parameter estimation and model calibration are key problems in the application of biofilm models in engineering practice, where a large number of model parameters need to be determined usually based on experimental data with only limited information content. In this article, identifiability of biokinetic parameters of a biofilm model describing two-step nitrification was evaluated based solely on bulk phase measurements of ammonium, nitrite, and nitrate. In addition to evaluating the impact of experimental conditions and available measurements, the influence of mass transport limitation within the biofilm and the initial parameter values on identifiability of biokinetic parameters was evaluated. Selection of parameters for identifiability analysis was based on global mean sensitivities while parameter identifiability was analyzed using local sensitivity functions. At most, four of the six most sensitive biokinetic parameters were identifiable from results of batch experiments at bulk phase dissolved oxygen concentrations of 0.8 or 5 mg O(2)/L. High linear dependences between the parameters of the subsets (KO2,AOB,muAOB) and (KO2,NOB,muNOB) resulted in reduced identifiability. Mass transport limitation within the biofilm did not influence the number of identifiable parameters but, in fact, decreased collinearity between parameters, especially for parameters that are otherwise correlated (e.g., muAOB) and KO2,AOB, or muNOB and KO2,NOB). The choice of the initial parameter values had a significant impact on the identifiability of two parameter subsets, both including the parameters muAOB and KO2,AOB. Parameter subsets that did not include the subsets muAOB and KO2,AOB or muNOB and KO2,NOB were clearly identifiable independently of the choice of the initial parameter values.
参数估计和模型校准是生物膜模型在工程实践中应用的关键问题，在工程实践中，通常需要根据信息含量有限的实验数据来确定大量模型参数。在本文中，仅基于铵、亚硝酸盐和硝酸盐的主体相测量，评估了描述两步硝化作用的生物膜模型的生物动力学参数的可识别性。除了评估实验条件和可用测量的影响外，还评估了生物膜内传质限制和初始参数值对生物动力学参数可识别性的影响。可识别性分析参数的选择基于全局平均灵敏度，而使用局部灵敏度函数分析参数可识别性。在主体相溶解氧浓度为0.8或5mg O₂/L的间歇实验结果中，六个最敏感的生物动力学参数中最多有四个是可识别的。子集（KO₂，AOB，μAOB）和（KO₂，NOB，μNOB）的参数之间的高线性相关性导致可识别性降低。生物膜内的传质限制并不影响可识别参数的数量，但实际上降低了参数之间的共线性，特别是对于那些原本相关的参数（例如，μAOB）和KO₂，AOB，或μNOB和KO₂，NOB）。初始参数值的选择对两个参数子集的可识别性有显著影响，这两个子集都包括参数μAOB和KO₂，AOB。不包括子集μAOB和KO₂，AOB或μNOB和KO₂，NOB的参数子集，无论初始参数值如何选择都是明显可识别的。
