Long-term dynamics of the bacterial community in a Swedish full-scale wastewater treatment plant

ABSTRACT

The operational efficiency of activated sludge wastewater treatment plants depends to a large extent on the microbial community structure of the activated sludge. The aims of this paper are to describe the composition of the bacterial community in a Swedish full-scale activated sludge wastewater treatment plant, to describe the dynamics of the community and to elucidate possible causes for bacterial community composition changes. The bacterial community composition in the activated sludge was described using 16S rRNA gene libraries and monitored for 15 months by a terminal restriction fragment (T-RF) length polymorphism (T-RFLP) analysis of the 16S rRNA gene. Despite variable environmental conditions, a large fraction of the observed T-RFs were present at all times, making up at least 50% in all samples, possibly representing a relatively stable core fraction of the bacterial community. However, the proportions of the different T-RFs in this fraction as well as the T-RFs in the more variable fraction showed a significant variation over time and temperature. The difference in community composition between summer and winter coincided with observed differences in floc structure. These observations suggest a relationship between floc properties and bacterial community composition, although additional experiments are required to determine causality.

KEYWORDS:

• Wastewater treatment
• activated sludge
• bacterial population dynamics
• terminal restriction fragment length polymorphism analysis
• 16S rRNA gene sequence analysis

Acknowledgements

We thank the staff at Gryaab AB for assistance in obtaining samples. We thank the staff at the Genomics Core Facility platform at the Sahlgrenska Academy, University of Gothenburg, for assistance with the T-RFLP analysis.

Disclosure statement

No potential conflict of interest was reported by the authors.

ORCID

Britt-Marie Wilén http://orcid.org/0000-0001-6155-7759

Additional information

Funding

The research was funded by a grant from FORMAS (The Swedish Research Council for Environment, Agricultural Sciences and Spatial Planning).