Modeling of a vapour-phase fungi bioreactor for the abatement of hexane: fluid dynamics and kinetic aspects

During some previous works, a packed-bed lab-scale biofilter (177¿10-6 m3), inoculated with a selected strain of Aspergillus niger had been tested for the abatement of hexane vapors, showing a maximum elimination capacity of 200 g hexane/m3 reactor/h. A steady-state mathematical model taking into account axial dispersion effect was applied to describe the process and predict experimental results, but many model parameters could not be calculated from experimental data. The aim of the present work was to carry out further investigations to accurately determine the dispersion coefficient and the kinetics parameters, in order to verify the effective validity of the model. Analysis of residential time distribution revealed the presence of a certain degree of axial dispersion (dispersion coefficient D of 1.22¿10-4 m2/s). Experimental data from kinetic trials carried out in reduced height reactors, together with data from full-scale runs, were elaborated to estimate the kinetic saturation constant (Ks), the coefficient yield (Y), the maximum growth rate (µmax) and maximum substrate degradation rate (rmax). All these parameters were introduced into the model which was then solved by simulation software finding out a quite good correlation between experimental and theoretical results.