Estudo do comportamento de um filtro biológico percolador com laterais abertas aplicado ao pós-tratamento de efluente de reator UASB

Abstract

This thesis aimed to evaluate the behavior of a novel design of a Trickling Filter with open sidewalls, developed at DESA-UFMG, Brazil, called Open Trickling Filter (OTF), applied to the post-treatment of sanitary effluent from a UASB reactor. The OTF was assessed under different hydraulic loading rates and packing material height, without the step of secondary settlement, regarding its hydrodynamics, performance (removal of solids, organic matter and nitrogen), the influence of environmental factors on nitrification and the transfer of oxygen. The hydrodynamic behavior was assessed through tests with tracers and adjustments to the mathematical models representing the actual flow. The filter´s ability to transfer oxygen to the liquid was evaluated for its original configuration (with open sides) and the filter simulating a conventional unit (with closed sides) by means of a non-reactive tracer gas. The flow regime of the OTF tended to plug flow. The mean residence time observed (12 to 22 min) was possibly due to the biofilm´s draining capacity, the influent´s distribution conditions and packing material moisture. The additional polishing of suspended solids and organic matter in the OTF was substantial, taking into account that its influent (UASB reactor effluent) had low biodegradable fractions, and also the filter had low hydraulic retention time. Nitrification in the OTF was affected from applied loading rates of 0.15 kg BODtotal.m-3.d-1, 0.03 kg BODsoluble.m-3.d-1 and 2.5-3.0 g NH4 +-N.m-2.d-1 (contact load of ammonium). The results of the filter´s ability to transfer oxygen were similar for the hydraulic loading rates applied. The closed sided filter showed slightly larger ability to transfer oxygen than the filter in its original open configuration. Considering the system´s great simplicity, no mechanization and small footprint, the performance results obtained can be considered satisfactory. It is suggested that the open trickling filter is suitable for small communities, especially at developing countries.