Reator híbrido associando reator UASB e reator radial de leito fixo (RRLF), em escala piloto, no tratamento de esgoto sanitário

Abstract

Integrated anaerobic/aerobic systems have been considered feasible alternatives concerning technical and economic aspects for treating domestic wastewaters. This paper presents the results obtained from the operation of this new reactor configuration, made up of a central unit – an upflow anaerobic sludge blanket reactor (UASB), with a working volume of 286 L, associated to a radial-flow aerobic immobilized- biomass (RAIB), with a working volume of 215 L. The RAIB reactor circles the solid/liquid/gas separation zone. The main modification in the UASB reactor concerns this association with the RAIB. The UASB effluent was distributed through openings along its side walls to the RAIB, allowing the elimination of collecting channels and feeding devices from the latter reactor. The objective of this work was to promote organic matter (raw and soluble) and nitrogen removal from domestic sewage. Organic matter (as COD) and volatile suspended solids removal achieved efficiencies of 80 % and 89 %, respectively. Under stable operational conditions, the system effluent presented COD and volatile suspended solids values of 110 mg·L-1 and 16 mg·L-1, respectively. Efficiencies of 90 % for COD and volatile suspended solids removal were achieved with a organic loading rate of 4,0 kg COD·m-3·d-1. This integrated system has shown to be a valid configuration, efficiently removing organic matter and suspended solids from the domestic wastewater. However, contrarily to expectations based on the previous studies with RAIB, nitrification was poor. Therefore, modifications to the RAIB design must be considered for the establishment of nitrogen removing processes.