Packing Material Evolutions and Odorous Abatement of Peat and Heather Biofilters Operating in Rendering Industry

Abstract

In this paper, the performances of three industrial biofilters treating rendering odorous emissions and the packing material evolution are presented and discussed. The biofilters were packed with a mixture of peat and heather, treating about 50 000 m3.h-1 of rendering gases which presented typical odorous concentrations ranging from 1 350 to 22 000 OU.m-3 for ambient air from industrial facilities, and from 13 000 to 184 000 for processes gas (mixture of non-condensable and air from fat presses). During the two first months of running, the packing material has shown a rapid compaction of 30 to 40 cm, representing a 20 to 26.7 % reduction of the volume. pH of biofilters were compared to new material, showing a drastic acidification in the deeper part. The bacterial count on PCA medium showed that bacterial density depends on the packing pH, which also induces a selection of micro-organism species. The low colonization (inferior to 9.4x104 CFU.g-1) can be explained by the lack of inoculation at biofilter start-up, the lack of nutrients supply and by acidic pH.