The post-treatment of effluents from anaerobic reactors is normally a mandatory step to meet the emission standards. The results presented here show the feasibility of using a new configuration of biological aerated filter (BAF) in the post-treatment of UASB reactors. The multi-stage BAF presents an anaerobic chamber (V=12.6L), followed by an aerobic chamber (V=30L) and an anoxic chamber (V=26.4L), all in series (total V=70L). This study examined the removal of suspended solids (SS), COD and BOD5. Three multi-stage BAF filled with three different packing materials were used: lids and bottlenecks of PET bottles (165m²/m³), gravel n. 4 (50m²/m³) and Pall rings 1.5'' (135m²/m³). The reactors were operated with the values of hydraulic detention time (HDT) of 4.1, 8.2 and 12.3 hours, and three superficial application rates (21, 12 and 8m³/m².d). COD removal efficiencies of 90% for BAF 1 and 3, and 85% for BAF 2 were obtained, being the removal independent of the HDT applied to BAF. The removal of SS was higher in BAF containing Pall rings, probably due to the higher voidage of this material.
Post-treatment of UASB reactor; BAS multi-stage; removal of COD; SS removal
