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

Weissbrodt, David G.; Holliger, Christof; Morgenroth, Eberhard

doi:10.1002/bit.26295

Cited by 23 publications

(5 citation statements)

References 59 publications

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“…Then, for all conditions, preferential selection for PAOs and GAOs will result from a duly operated anaerobic selector by managing the contact time between the influent wastewater and the biomass to enable hydrolysis, fermentation, and VFA uptake by these organisms prior to switching aeration or anoxic phases on. In granular sludge systems, this can occur via well-designed bed geometries and hydraulic conditions under slow up-flow feeding conditions, and/or by the integration of a subsequent anaerobic batch phase to promote the hydrolysis, fermentation, and uptake of VFAs by PAOs or GAOs (de Kreuk and van Loosdrecht, 2004; Weissbrodt et al, 2013b; Lochmatter and Holliger, 2014; Pronk et al, 2015b; Wagner et al, 2015; Derlon et al, 2016; Weissbrodt et al, 2017; Winkler et al, 2018; Toja Ortega et al, 2022; van Dijk et al, 2022).…”

Section: Discussionmentioning

confidence: 99%

“…Concentrations of total (TSS), inorganic (ISS), and volatile (VSS) suspended solids were analyzed according to the Standard Methods (APHA-AWWA-WEF, 2012). Heights of biomass beds in the reactors were measured daily using tailor’s tape measures to manage the anaerobic contact time (Weissbrodt et al, 2017). Evolutions of particle size distributions in the biomass were followed using a Quantiment 500 Image Analyzer (Leica Cambridge Instruments, UK).…”

Section: Methodsmentioning

confidence: 99%

See 1 more Smart Citation

Production of extracellular polymeric substances in granular sludge under selection forAccumulibacterandCompetibacter

Guimarães

Gubser

Lin

et al. 2023

Preprint

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Granular sludge intensifies the removal of nutrients from wastewater. Granules structured by extracellular polymeric substances (EPS) can be recovered as biomaterial. Links between microbial selection and EPS formation during granulation need to get uncovered. We inoculated anaerobic-aerobic sequencing batch reactors with either flocs or granules to study the relationships between microbial selection, bioaggregation, exopolymer formation, and EPS composition. Selection for slow-growing organisms like the model polyphosphate-accumulating organism "Candidatus Accumulibacter" (max. 83% vs. amplicon sequencing read counts) and glycogen-accumulating organism "Ca. Competibacter" (max. 45%) sustained granulation. Gel-forming exopolymers were produced as high as above 40% of the volatile solids of the biomass by stepwise increase of the organic loading rate (0.3 to 2.0 g CODAc d-1 LR-1). Confocal laser scanning microscopy, FT-IR spectroscopy, and HPAE-PAD chromatography revealed the complex and dynamic chemical compositions of the structural EPS in relation to microbial population shifts along reactor regimes. The analysis of 20 representative genomes of "Ca. Accumulibacter" and "Ca. Competibacter" recovered from public databases revealed their functional potential to produce EPS among other representative wastewater microorganisms. The more than 40 functional gene categories annotated highlight the complexity of EPS metabolic networks from monomers processing to assembly, export, and epimerizations. The combination of ecological engineering principles and systems microbiology will help unravel and direct the production of EPS from wastewater, valorizing residual granular sludge into beneficial biomaterials for the circular economy.

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Section: Discussionmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Production of extracellular polymeric substances in granular sludge under selection forAccumulibacterandCompetibacter

Guimarães

Gubser

Lin

et al. 2023

Preprint

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“…Flocs are also suspected to play an important role in capturing and converting the particulate organic substrates (Pronk et al 2015b;Derlon et al 2016;Campo et al 2020;Layer et al 2020a), thus having a key influence on the proper operation of AGS systems. However, most existing AGS models neglect their presence and in turn their contribution to the system performance (Beun et al 2001; de Kreuk et al 2007;Xavier et al 2007;Ni & Yu 2010;Kagawa et al 2015;Weissbrodt et al 2017). We advocate the structure of AGS models should allow predicting the presence of floccular biomass to best predict the performances of AGS systems.…”

Section: Experiences From Full-scale Ags-based Wwtp and Implication F...mentioning

confidence: 99%

“…Most of these models are therefore able to predict the microbial selection of storing organisms (Lübken et al 2005;Xavier et al 2007;Ni & Yu 2010;Kagawa et al 2015). But while hydraulic selection is also a key factor governing granules formation, only a few models are able to predict the coexistence of flocs/granules (Su & Yu 2006;Su et al 2013;Dold et al 2018), the plug-flow feeding (Weissbrodt et al 2017;Dold et al 2018), the stratification of the sludge bed (Su et al 2013) or the selective removal of slow settling biomass (Su et al 2013;Dold et al 2018). Those aspects are, however, key features of AGS systems, as detailed in section 1.1.…”

Section: Limitations Of Existing Aerobic Granular Sludge Modelsmentioning

confidence: 99%

Modelling of aerobic granular sludge reactors: the importance of hydrodynamic regimes, selective sludge removal and gradients

Derlon

Villodres

Kovács

et al. 2022

Water Science and Technology

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Hydraulic selection is a key feature of aerobic granular sludge (AGS) systems but existing aerobic granular sludge (AGS) models neglect those mechanisms: gradients over reactor height (Hreactor), selective removal of slow settling sludge, etc. This study aimed at evaluating to what extent integration of those additional processes into AGS models is needed, i.e., at demonstrating that model predictions (biomass inventory, microbial activities and effluent quality) are affected by such additional model complexity. We therefore developed a new AGS model that includes key features of full-scale AGS systems: fill-draw operation, selective sludge removal, distinct settling models for flocs/granules. We then compared predictions of our model to those of a fully mixed AGS model. Our results demonstrate that hydraulic selection can be predicted with an assembly of 4 continuous stirred tank reactor in series together with a correction code for plug-flow. Concentration gradients over the reactor height during settling/plug-flow feeding strongly impact the predictions of aerobic granular sludge models in terms of microbial selection, microbial activities and ultimately effluent quality. Hydraulic selection is a key to predict selection of storing microorganisms (phosphorus-accumulating organisms – PAO and glycogen-accumulating organisms – GAO) and in turn effluent quality in terms of total phosphorus, and for predicting effluent solid concentration and dynamic during plug-flow feeding.

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“…sequencing batch reactors, it is known that semi-plug flow behaviour exists during the unaerated feeding phase, but this has not been considered in whole-reactor models yet (Weissbrodt et al, 2017).…”

Section: A C C E P T E D Accepted Manuscriptmentioning

confidence: 99%

Modelling anaerobic, aerobic and partial nitritation-anammox granular sludge reactors - A review

Baeten

Batstone

Schraa³

et al. 2019

Water Research

111

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Wastewater treatment processes with granular sludge are compact and are becoming increasingly popular. Interest has been accompanied by the development of mathematical models. This contribution simultaneously reviews available models in the scientific literature for anaerobic, aerobic and partial nitritation-anammox granular sludge reactors because they comprise common phenomena (e.g. liquid, gas and granule transport) and thus pose similar challenges. Many of the publications were found to have no clearly defined goal. The importance of a goal is stressed because it determines the appropriate model complexity and helps other potential users to find a suitable model in the vast amount of literature. Secondly, a wide variety was found in the model features. This review explains the chosen modelling assumptions based on the different reactor types and goals wherever possible, but some assumptions appeared to be habitual within fields of research, without clear reason. We therefore suggest further research to more clearly define the range of operational conditions and goals for which certain simplifying assumptions can be made, e.g. when intragranule solute transport can be lumped in apparent kinetics and when biofilm models are needed, which explicitly calculate substrate concentration gradients inside granules. Furthermore, research is needed to better mechanistically understand detachment, removal of influent particulate matter and changes in the mixing behaviour inside anaerobic systems, before these phenomena can be adequately incorporated in models. Finally, it is suggested to perform fullscale model validation studies for aerobic and anammox reactors. A spreadsheet in the supplementary information provides an overview of the features in the 167 reviewed models.

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

Cited by 23 publications

References 59 publications

Production of extracellular polymeric substances in granular sludge under selection forAccumulibacterandCompetibacter

Production of extracellular polymeric substances in granular sludge under selection forAccumulibacterandCompetibacter

Modelling of aerobic granular sludge reactors: the importance of hydrodynamic regimes, selective sludge removal and gradients

Modelling anaerobic, aerobic and partial nitritation-anammox granular sludge reactors - A review

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