Caracterização sazonal da microbiota procarionte de reatores anaeróbios do tipo UASB em escala real tratando esgoto doméstico no Sul do Brasil

Abstract

Anaerobic digestion processes have been successfully used to remove pollutants in wastewater. In this context, Upflow Anaerobic Sludge Blanket (UASB) reactors are treatment alternatives used in different parts of the world; however, in temperate environments, they are subject to a strong seasonal influence. The operational control of these units in Wastewater Treatment Plants (WWTPs) is commonly done through physical-chemical analyses, so aspects related to microbial ecology are controlled indirectly. Thus, understanding the structural dynamics of the microbiota in these environments is essential to propose alternatives to improve the quality of treated effluents. In this study, for one year, high-performance sequencing, associated with bioinformatics tools for taxonomic annotation and functional prediction, was used to characterize the microbial community present in the sludge of biodigesters on full-scale, treating domestic sewage at ambient temperature. Among the most representative phyla stood out Desulfobacterota (20.21?28.64%), Proteobacteria (7.48? 24.90%), Bacteroidota (10.05?18.37%), Caldisericota (9.49?17.20%), and Halobacterota (3.23?6.55%). The genus Methanolinea was linked to the efficiency in removing the Chemical Oxygen Demand (COD), Bacteroidetes_VadinHA17 to the concentration of volatile fatty acids (VFAs), and CI75cm212 to the increase in temperature. In addition to these taxonomic elements, groups such as Desulfovibrio, Spirochaetaceae_uncultured, Methanosaeta, Lentimicrobiaceae_unclassified, and ADurb.Bin063-1 were important in shaping the microbial community in a co-occurrence network. Among the principal metabolic functions associated with the community, protein and amino acid metabolism stood out (7.74?8.00%), and genes linked to VFA metabolism showed higher relative abundance for the autumn and winter periods (15.36 ± 5.46°C), coinciding with the highest richness and evenness recorded. Despite the differences in diversity and taxonomic composition between the periods, no significant changes were observed in the efficiency of the biodigesters. The present study contributed to understanding the dynamics of microbial communities that act in the anaerobic digestion of low-concentrated domestic sewage under the influence of seasonal factors, providing evidence for potential sludge applications, improvements in operational processes, and treatment efficiency. [resumo fornecido pelo autor]