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A bench‐scale bioreactor was operated under two different technologies of membrane bioreactor and hybrid moving bed bioreactor‐membrane bioreactor at hydraulic retention time 6–16 h, sludge retention time 6–24 days, and mixed liquor suspended solids 3400–7800 mg L−1. Analyses of their bacterial community structures showed marked differences between the two technologies for global communities but not for dominant phylotypes, and the domination of different bacterial phylotypes for the different operational conditions. Tetrasphaera genus was ubiquitous (1.1%–19.2% relative abundance) in both bioprocesses. Fodinibacter (0.04%–7.75%) was found to positively correlate with other dominant phylotypes, highlighting the relevance of Intrasporangiaceae family in membrane‐based technologies. Oligotypes distribution of dominant phylotypes showed that certain strains were favored at all operational conditions. Linkage with operational conditions determined that the presence/absence of carriers deeply impacted the relative abundance of dominant phylotypes. The results are relevant to discern the effect of operational conditions over bacterial communities in membrane‐based technologies. © 2018 American Institute of Chemical Engineers AIChE J, 65: 536–548, 2019 [ABSTRACT FROM AUTHOR]

Autotrophic nitrogen removal systems have been implemented at full-scale and provide an efficient way for nitrogen removal from industrial and urban wastewaters. Our study present qualitative and quantitative analysis of archaeal and bacterial amoA genes and Candidatus Brocadiales bacteria analyzed in six full-scale autotrophic nitrogen removal bioreactors. The results showed that ammonium oxidizing bacteria (AOB) were detected in all bioreactors. However, ammonium oxidizing archaea (AOA) were detected only in the non-aerated technologies. Conversely, different Candidatus Brocadiales phylotypes appeared due to differences in influent wastewater composition and hydraulic retention time (HRT). In the same terms multivariate redundancy analysis confirmed that AOA was positively correlated with temperature, ammonium concentration and low HRT. However, AOB population was positively correlated with pH, temperature, and dissolved oxygen concentration. Our data suggested a correlation between the microorganisms involved in the nitrogen removal performance and the operational conditions in the different full-scale bioreactors. © 2017 American Institute of Chemical Engineers AIChE J, 64: 457-467, 2018 [ABSTRACT FROM AUTHOR]