Predicting the effect of biofilm growth on the pressure drop over a biofilter

[摘要] ENGLISH ABSTRACT : Hydrogen sulphide is a poisonous gas produced by several industries. It is therefore crucialto investigate and mathematically model the environmentally friendly biofiltration process,which has the ability to remove poisonous gasses, such as hydrogen sulphide, from an airstream. In this study two approaches are used for modelling biofilm growth in threedifferent biofilters, i.e. an empirical and analytical approach. In the empirical modellingapproach, the pressure drop prediction of the Modified-Macdonald equation, the existinggranular rectangular Representative Unit Cell (RUC) model and the model of Comiti andRenaud are used to determine the changes in biofilm affected porosity, specific surface area,tortuosity and biofilm thickness. The results are obtained by using Excel R Solver, which isbased on an optimization method. Thereafter a sensitivity analysis is performed in orderto analyze the effect of the sphericity. The analytical modelling approach involves only theRUC model. The first step is to predict the biofilm thickness. Thereafter, two methodsare suggested for predicting the biofilm affected specific surface area. The first method isbased on an approach suggested in the literature. In the second method, the RUC modelis used to express the pressure drop in terms of the biofilm affected specific surface area,which yields the adapted RUC model. The biofilm affected specific surface area values arethen obtained by making use of experimental pressure drop data and superficial velocityvalues. After incorporating both the analytically and empirically determined sphericityvalues into the adapted RUC model, the pressure drop results show the significant effectthat the sphericity value has on the model predictions. Finally, a sensitivity analysis isperformed on the input parameters to the model.

[发布机构] Stellenbosch University