Dynamics and response of microbial diversity to nutritional condition in denitrifying bioreactor treating laundry wastewater

The aim of this study was to evaluate the microbial community structure and phylogenetic diversity under influence of nutritional conditions and hydraulic retention time (HRT) in fluidized bed reactors (FBR) operated in HRT of 8 hours (FBR1) and 12 hours (FBR2) for the removal of linear alkylbenzene sulfonate (LAS) from laundry wastewater. These reactors were inoculated with biomass from the activated sludge system and feeding with nitrate (150 mg/L) and ethanol (100 mg/L) in synthetic medium following operational phases: adaptation – without laundry wastewater (Phase I) com ou sem nitrato??mencionar, LAS addition in laundry wastewater (Phase II), with nitrate (Phase III), ethanol without (Phase IV), nitrate without (Phase V). After each phase biofilm samples from FBR1 and FBR2 was submitted to microbial sequencing through Mi-Seq Illumima®. Greater LAS removal was observed after 313 days of operation being 99±3% in FBR2 (22.5±5.9 mg LAS/L affluent) and 93±12% in FBR1 (20.6±4.4 mg LAS/L affluent). Microbial shift showed genus abundance related to denitrification and LAS degradation. In Phase I, were identified denitrifying bacteria similar to Acinetobacter, Flavobacterium, Shingobium and Xanthobacter. For Phases with laundry wastewater addition were identified bacteria similar to Dechloromonas, Zoogloea, Novosphingobium, Pseudomonas, Acinetobacter and Desulfobulbus. These genera were related to LAS and aromatic compounds degradation.