Biological Processing Capacities and Biomass Growth in Waste Water Treatment by Infiltration On two Kinds of Sand

In this article, work is presented which highlights the biological processing capacities of urban waste water within porous media of different textures. A comparative study on the growth of biomass coupled with the general mechanisms for gas transfer through two biological beds is undertaken. Infiltration-percolation beds are simulated using columns filled with sands of different origins and structures. These are periodically fed using an influent with a COD load of 525 mg/l and 54 mg/l of Kjeldahl nitrogen. The results obtained show that a balanced development of biomass, including growth and regression phases, is intrinsically related to the physical nature of the material support. Using core samples from the columns and oxymetry probes set at various heights, it is shown that both the vertical distribution of the biofilm in the columns and oxygenation of the porous media during a rest period also correlate with the support structure. The effectiveness of biological treatment is optimum for carbon with alluvial sand rather than crushed sand, with this tendency being significantly reversed for nitrogen abatement.