Influência da origem do inóculo no enriquecimento de comunidades microbianas ANAMMOX e SRAO

Abstract

Biological treatment of nitrogen rich wastewater has a promising potential, specially when considering the biological anaerobic removal of. The ANAMMOX process is a metabolic route mediated by microorganisms characterized by anaerobic oxidation of ammonia using nitrite as final electron acceptor and generating nitrogen gas as final product. Since 2001, another recently discovered was the anaerobic biological process for ammonia removal called sulfate-reduction ammonium oxidation (SRAO) which associates ammonium oxidation and sulfate removal. This process is ruled by ammonia oxidation coupled to sulfate reduction, releasing gaseous nitrogen and elemental sulfur. The aim of this work was to evaluate the potential for ANAMMOX and SRAO enrichment of microorganisms using batch reactors. For the ANAMMOX enrichments, four anaerobic inoculum was evaluated (Experiment I), which were: thermophilic sludge used on the treatment of vinasse (I1), two inoculum from poultry wastewater treatment plants: Pereiras (I2) and Dacar (I3), and an inoculum from a reactor used to treat acid mine drainage (I4). In addition, it was also evaluated the adaptation potential of an aerobic inoculum from an activated sludge plant treating sewage for adaptation to the ANAMMOX (reactor R1) and SRAO (reactor R2) process in batch reactors (Experiment II). The consumption of nitrogen compounds, sulfate, COD and pH were monitored for 322 days for Experiment I and 154 days for Experiment II. In experiment I, it was observed a period of intense denitrifying activity, which was disadvantaged with the increase of nitrite and ammonia concentration. However, this activity remained until the end of the operation probably because dead cells were retained and could be used as an electron donor via heterotrophic denitrification. The presence of ANAMMOX microorganisms was detected by real-time PCR technique in the batch reactor with the inoculum from the UASB reactor treating poultry wastewater. This was only possible probably because the inoculum already treated nitrogen compounds, which favored the presence of these microorganisms. In Experiment II, neither ANAMMOX activity or SRAO activity were observed, probably due to the short operating time. The presence of ANAMMOX bacteria was not detected in these reactors.