Overall mass transfer coefficients (K G a and K L a) were determined experimentally for four different-nature packing materials used in gas-phase biotrickling filters. A simple methodology based on overall mass balances and following a standard procedure allowed to calculate the mass transfer coefficients under different operating conditions corresponding to usual biotrickling filtration situations. Results showed an increase of mass transfer resistance when increasing the empty bed residence time (EBRT) of the reactor for all packing materials. Experimental results were fitted to existing and well-accepted correlations used in conventional biofilter or biotrickling filter modeling. The comparison of experimental and theoretical data showed huge discrepancies. Simple correlations for the experimental data obtained in this study were also suggested.

Peer ReviewedPostprint (published version

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Biological techniques for the removal of gaseous pollutants such as hydrogen sulfide have proved to be effective, environmentally friendly and economically viable. However, when high concentrations of hydrogen sulfide are treated the process is severely restricted by the oxygen deficit in the liquid phase. Thus, when the oxygen concentration is below the stoichiometric requirement, elemental sulfur is formed and accumulates in the packing material, increasing operating costs and, in extreme cases, requiring the bioreactor to be shut down. In this study the oxygen transfer efficiency provided by a membrane diffuser is evaluated under typical pressure and salinity conditions used for the biological treatment of hydrogen sulfide in biogas. The aim was to determine the optimal operating parameters for enhanced oxygen transfer. The addition of pure oxygen with a membrane diffuser to increase the oxygen transfer rate and the use of a non-aqueous phase to improve oxygen transfer in a bioscrubber system are also evaluated.

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