Characterization of the microbial communities and treatment units in a waste stabilization pond system treating wastewater from an industrial complex located in Northeastern Brazil

The Multifactory Effluent Treatment Plant (ETE-MF), located within an industrial complex in Recife, Brazil, receives effluents from 15 industries from different sectors, as well as domestic wastewater. This plant is recognized as efficient by the state sanitation company. This raises the question of what are the causes of this scenario and whether this process could be replicated. In this sense, this research aimed to reveal the physicochemical aspects of the MF-WWTP and the microbial community that has established itself there during decades of operation. Overall, the results showed COD (Chemical Oxygen Demand) removal of 84.0% and COD/BOD (BOD - Biological Oxygen Demand) ratios of 1.78 and 5.79 for raw and filtered untreated effluents, respectively. The microbial community analysis showed that bacteria belonging to the Fervidobacterium genus was the most abundant in all sampled points in all ponds, with an average relative abundance of 64%. This organism belongs to the Thermotogaceae family, widely distributed in nature and frequently found in salt flats, oil and petroleum wells, refineries and biodigesters and seems to be crucial for the performance of the treatment plant. This polishing process was completed by the microalgae community found mainly in pond 3, where the community was mainly composed of the genera Cyclotella and Planktothri x. The results provided scientific evidence for the technical analysis that the MF-WWTP has bioremediation potential and indicates that this efficiency is due to the microbial composition of the system.