Effect of biofilm thickness on the activity and community composition of phosphorus accumulating bacteria in a moving bed biofilm reactor

Rellegadla Sandeep; Juan Franco Muscolino; Williane Vieira Macêdo; Maria Piculell; Magnus Christensson; Jan Struckmann Poulsen; Jeppe Lund Nielsen; Leendert Vergeynst

doi:10.1016/j.watres.2023.120599

Effect of biofilm thickness on the activity and community composition of phosphorus accumulating bacteria in a moving bed biofilm reactor

Water Res. 2023 Oct 15:245:120599. doi: 10.1016/j.watres.2023.120599. Epub 2023 Sep 9.

Authors

Rellegadla Sandeep¹, Juan Franco Muscolino², Williane Vieira Macêdo², Maria Piculell³, Magnus Christensson³, Jan Struckmann Poulsen⁴, Jeppe Lund Nielsen⁴, Leendert Vergeynst²

Affiliations

¹ Centre for Water Technology (WATEC), Department of Biological and Chemical Engineering, Aarhus University, Aarhus, Denmark. Electronic address: sandeepr@bce.au.dk.
² Centre for Water Technology (WATEC), Department of Biological and Chemical Engineering, Aarhus University, Aarhus, Denmark.
³ AnoxKaldnes AB, Lund, Sweden.
⁴ Center for Microbial Communities, Department of Chemistry and Bioscience, Aalborg University, Aalborg, Denmark.

PMID: 37717325
DOI: 10.1016/j.watres.2023.120599

Abstract

Can biofilms enhance the rates of phosphorus removal in wastewater treatment? In order to narrow the scientific gap on the effect of biofilm thickness on the activity and microbial community of phosphorus-accumulating bacteria, this study investigated biofilms of 30 to 1000 µm thickness in a moving bed biofilm reactor. Measurements on 5 different biofilm carriers showed that biomass-specific phosphorus release and uptake rates increased as a function of biofilm thickness for biofilms thinner than about 110 µm but were lower for thicker biofilms of about 550-1000 µm. The reduced phosphorus uptake and release rates in the thickest biofilms can result from substrate mass transfer limitations whereas the low activity in the thinnest biofilms can be related to a too high turnover rate in the biofilm due to heterotrophic growth. Additionally, the microbial ecology of the different biofilms confirms the observed phosphorus uptake and release rates. The results from the full-length 16S rRNA gene sequencing of the bacterial community showed that the thicker biofilms were characterized by higher relative abundance (40-58%) of potential phosphorus accumulating genera Zoogloea, Acinetobacter, Dechloromonas and Ca. Accumulibacter. In contrast, the thinner biofilms were dominated by the genus Ferribacterium (34-60%), which might be competing with phosphorus-accumulating bacteria as indicated by the relatively high acetate uptake rates in the thinner biofilms. It is concluded that there is an optimal biofilm thickness of 100-500 µm, at which the phosphorus accumulating bacteria have the highest activity.

Keywords: Microbial activity; Microbial community composition; Moving bed biofilm reactor: Biofilm thickness, biological phosphorus removal; Phosphorus accumulating bacteria.