Multilevel correlations in the biological phosphorus removal process: From bacterial enrichment to conductivity‐based metabolic batch tests and polyphosphatase assays

Abstract

Enhanced biological phosphorus removal (EBPR) from wastewater relies on the preferential selection of active polyphosphate-accumulating organisms (PAO) in the underlying bacterial community continuum. Efficient management of the bacterial resource requires understanding of population dynamics as well as availability of bioanalytical methods for rapid and regular assessment of relative abundances of active PAOs and their glycogen-accumulating competitors (GAO). A systems approach was adopted here toward the investigation of multilevel correlations from the EBPR bioprocess to the bacterial community, metabolic, and enzymatic levels. Two anaerobic-aerobic sequencing-batch reactors were operated to enrich activated sludge in PAOs and GAOs affiliating with "Candidati Accumulibacter and Competibacter phosphates", respectively. Bacterial selection was optimized by dynamic control of the organic loading rate and the anaerobic contact time. The distinct core bacteriomes mainly comprised populations related to the classes Betaproteobacteria, Cytophagia, and Chloroflexi in the PAO enrichment and of Gammaproteobacteria, Alphaproteobacteria, Acidobacteria, and Sphingobacteria in the GAO enrichment. An anaerobic metabolic batch test based on electrical conductivity evolution and a polyphosphatase enzymatic assay were developed for rapid and low-cost assessment of the active PAO fraction and dephosphatation potential of activated sludge. Linear correlations were obtained between the PAO fraction, biomass specific rate of conductivity increase under anaerobic conditions, and polyphosphate-hydrolyzing activity of PAO/GAO mixtures. The correlations between PAO/GAO ratios, metabolic activities, and conductivity profiles were confirmed by simulations with a mathematical model developed in the aqueous geochemistry software PHREEQC.

Modeling hydraulic transport and anaerobic uptake by PAOs and GAOs during wastewater feeding in EBPR granular sludge reactors

“…Among those, the impacts of the VFA composition on PAO and GAO metabolisms and selection (Gonzalez-Gil and Holliger, 2011;Lopez-Vazquez et al, 2009;Weissbrodt et al, 2013b), and of different ranges of substrates and salinities on additional microbial processes can be studied (Pronk et al, 2014(Pronk et al, , 2015aWelles et al, 2014). Implementation of speciation and acid-base equilibria in PHREEQC (Parkhurst, 1995) may help managing pH gradients that establish across sludge beds in function of active metabolisms (Weissbrodt et al, 2014b). Implementation of speciation and acid-base equilibria in PHREEQC (Parkhurst, 1995) may help managing pH gradients that establish across sludge beds in function of active metabolisms (Weissbrodt et al, 2014b).…”

“…Latest molecular and ecophysiology investigations further highlighted that engineered EBPR microbial ecosystems consist of a diversity of populations within the PAO and GAO guilds, which could be considered in model extensions as well (Albertsen et al, 2016;Forbes et al, 2009;Lanham et al, 2013;Nielsen et al, 2012;Weissbrodt et al, 2014c;Welles et al, 2015). Implementation of speciation and acid-base equilibria in PHREEQC (Parkhurst, 1995) may help managing pH gradients that establish across sludge beds in function of active metabolisms (Weissbrodt et al, 2014b). The influence of microbial Figure 6.…”

“…Glycogen-accumulating organisms (GAOs) compete with PAOs for VFAs during anaerobic feeding of wastewater (Cech and Hartman, 1993). Hence, bacterial selection for EBPR is primarily driven by anaerobic uptake processes (Kong et al, 2001;Weissbrodt et al, 2014b).…”

Research progress on microbes in aerobic granular sludge

“…图 1 厌氧-好氧SBR工艺AGS中微生物的碳氮磷代谢过程示意图 [25] Figure 1 Diagram on C, N and P microbial metabolisms of AGS from anaerobic-aerobic SBRs [25] 多; DO=2 mg L 1 时, AGS中微生物群落最丰富, 主要 [34] . 代表性有机污染物条件下, AGS中能够降解该种有机 物的特定种(属)的微生物.…”

Caracterização da comunidade bacteriana da bacia do Rio Tietê por métodos independentes de cultivo.

“…Proteobacteria, Bacteroidetes, Firmicutes e Actinobacteria são caracterizados como os grupos mais abundantes em diversos trabalhos, sendo encontradas em diferentes ambientes, incluindo ecossistemas aquáticos (BOLHUIS et al, 2014;MARGIS, 2015;WANG et al, 2012). acidogênica e as bactérias pertencentes a este grupo são descritas entre as mais abundantes no processo de hidrólise e fermentação de matéria orgânica, frequentemente relacionadas à remoção de nitrogênio e fósforo (WEISSBRODT et al, 2014;WU et al, 2013), tendo sido observadas em alta densidade também por Llorens-Marès; Auguet e Casamayor (2012), em seu trabalho com micro-organismos dos sedimentos de ambientes aquáticos oligotróficos.…”