The research aimed at evaluating the operation of trickling filters (TF) post-UASB reactors without the secondary sedimentation stage, in terms of biochemical and chemical oxygen demand (BOD and COD) and total suspended solids (TSS) removal. The experimental apparatus consisted of one UASB reactor followed by four TF in parallel, each one filled with a different packing media. The UASB reactor was operated at a permanent hydraulic regime, while three operational conditions were imposed to the TF during the experimental period. In general, the UASB/TF systems were able to comply with the discharge standards. At low organic loading rates (OLR), no improvements in terms of organic matter removal, with the use of higher surface area packing media were observed. However, the use of a sponge-based packing media provided significant improvements on final effluent quality. The use of UASB/TF systems without secondary sedimentation can constitute an attractive alternative in terms of operational simplification of this technology, and an important strategy for domestic wastewater treatment in developing countries. However, the success of this technology is strictly connected to the correct anaerobic sludge management of the UASB reactor, in order to avoid overloads on the TF.
domestic wastewater; trickling filter; operation without secondary settlers; post-treatment; UASB reactor
