Mass transfer in a membrane aerated biofilm

We present experimental results of mass transfer of a non reactive tracer gas (neon) measured in aerobic heterotrophic biofilm developed from activated sludge. Biofilms are grown in various hydrodynamic conditions and the effective diffusivity is used to quantify the mass transfer through the biofilm. Beyond some cross-flow conditions, the effective diffusivity through the biofilm seems larger than in the bulk. This can be explained by a dispersion generated by convection inside the biofilm, as supported by an analytical flow model and in accordance to the numerical simulation proposed by Aspa et al. (2011). [Display omitted] ► Transport of neon through a membrane aerated biofilm was experimentally assessed. ► Diffusion and convection were found to contribute to mass transport through the MAB. ► An analytical model to calculate the axial convection through a biofilm was proposed. ► A transition Peclet number was found, in qualitative agreement with Aspa et al. (2011).