Abstract:
Hydrogen sulphide is a poisonous gas produced by several industries. It is therefore crucial
to investigate and mathematically model the environmentally friendly biofiltration process,
which has the ability to remove poisonous gasses, such as hydrogen sulphide, from an air
stream. In this study two approaches are used for modelling biofilm growth in three
different biofilters, i.e. an empirical and analytical approach. In the empirical modelling
approach, the pressure drop prediction of the Modified-Macdonald equation, the existing
granular rectangular Representative Unit Cell (RUC) model and the model of Comiti and
Renaud 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 is
based on an optimization method. Thereafter a sensitivity analysis is performed in order
to analyze the effect of the sphericity. The analytical modelling approach involves only the
RUC model. The first step is to predict the biofilm thickness. Thereafter, two methods
are suggested for predicting the biofilm affected specific surface area. The first method is
based on an approach suggested in the literature. In the second method, the RUC model
is 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 are
then obtained by making use of experimental pressure drop data and superficial velocity
values. After incorporating both the analytically and empirically determined sphericity
values into the adapted RUC model, the pressure drop results show the significant effect
that the sphericity value has on the model predictions. Finally, a sensitivity analysis is
performed on the input parameters to the model.
