BACKGROUND: Biofiltration technology has received much attention due to its effectiveness, low cost and environment friendly properties. It is used to remove odors caused chiefly by hydrogen sulfide (H2S) via biological treatments. RESULTS: In this study, numerical simulations using the thermal lattice Boltzmann method are implemented to investigate the effect of non-isothermal conditions on heterogeneous flow through three biofilter models that are partly filled with porous media. The generalized NavierStokes model based on the Brinkman-Forchheimerextended Darcy model is used to make several assumptions. CONCLUSIONS: The numerical results indicate that the Rayleigh number has significant influence on the removal efficiencies of biofilters. There also exist critical Rayleigh numbers for biofilters under non-isothermal conditions. If the Rayleigh number is less than the critical value, the flow heterogeneity will reduce with increasing Rayleigh number; otherwise, the flow heterogeneity will enhance with increasing Rayleigh number. Moreover, it was found that the performances of biofilters can be improved by designing non-isothermal conditions between the porous media layers, i.e. by adjusting the Rayleigh number to optimize the detention time of waste air. (c) 2012 Society of Chemical Industry