Seasonal Characterization of Bacterial Communities in Industrial Wastewater and Their Relationship with Flocculation Indices and Extracellular Polymeric Substances

Microbially driven flocculation in wastewater treatment continues to be a matter of intensive research, given that specific factors related to microbial assembly and flocculation processes are largely unknown. To better understand the seasonal dynamics of microbial structure composition within bioreactors and their relationship with flocculation, bacterial communities in an industrial secondary treatment basin were characterized through 16S rRNA gene sequences and compared in the presence of extracellular polymeric substances (EPSs) and specific water quality parameters. Among all water quality parameters, dissolved oxygen was highest in the winter, while temperature, conductivity, and total dissolved solids were highest in the summer. Flocculation was highest in the winter, and lowest in the summer, which was likely the result of different dominant bacterial taxa in each season. EPSs occurred at increased concentrations in most samples from the spring, though specific spatiotemporal patterns could not be fully determined. While the bacterial community composition did not differ spatially, significant seasonal differences reflected major temporal fluctuations of microbially related processes within the basin. These observations highlight the need to consider physicochemical aspects of treatment basins and their influence over bacterially driven flocculation to maximize the efficiency of treatment operations.