Continuous-flow aerobic granulation in plug-flow bioreactors fed with real domestic wastewater

Sun, Yi; Angelotti, Bob; Wang, Zhi‐Wu

doi:10.1016/j.scitotenv.2019.06.291

Cited by 62 publications

(46 citation statements)

References 39 publications

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“…It should be pointed out that the seed reactor overflow turbidity was only 0.77 ± 0.31 NTU, indicating excellent structural stability of these seed granules. The settling velocity of seed granules in ALR was as high as 54.2 m h −1 , which was comparable with those reported in previous studies, i.e., 18-60 m h −1 [14][15][16]. Table 2 shows that the nitrification efficiency was as high as 97%, indicating the excellent performance of these nitrifying granules.…”

Section: Characteristics Of Seed Granulessupporting

confidence: 87%

“…Technically, this challenge cannot be resolved in completely stirred tank reactors, in which bulk substrate concentration is expected to be low. Instead, plug flow reactors, in which deeper mass diffusion can be facilitated by a relatively higher initial substrate concentration, should be considered in future GMBR research [16]. Besides this mass diffusion problem, special attention should also be paid to the high sEPS concentration accumulated in the GMBR [22].…”

Section: Discussionmentioning

confidence: 99%

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Long-Term Stability of Nitrifying Granules in a Membrane Bioreactor without Hydraulic Selection Pressure

Zhang

Bott

et al. 2021

Processes

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To understand the long-term stability of nitrifying granules in a membrane bioreactor (GMBR), a membrane module was submerged in an airlift reactor to eliminate the hydraulic selection pressure that was believed to be the driving force of aerobic granulation. The long-term monitoring results showed that the structure of nitrifying granules could remain stable for 305 days in the GMBR without hydraulic selection pressure; however, the majority of the granule structure was actually inactive due to mass diffusion limitation. As a consequence, active biomass free of mass diffusion limitation only inhabited the top 60–80 µm layer of the nitrifying granules. There was a dynamic equilibrium between bioflocs and membrane, i.e., 25% of bioflocs attached on the membrane surface within the last nine days of the backwash cycle in synchronization with the emergence of a peak of soluble extracellular polymeric substances (sEPS), with a concentration of around 47 mg L−1. Backwash can eventually detach and return these bioflocs to the bulk solution. However, the rate of membrane fouling did not change with and without the biofloc attachment. In a certain sense, the GMBR investigated in this study functioned in a similar fashion as an integrated fixed-film activated sludge membrane bioreactor and thus defeated the original purpose of GMBR development. The mass diffusion problem and sEPS production should be key areas of focus in future GMBR research.

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Section: Characteristics Of Seed Granulessupporting

confidence: 87%

Section: Discussionmentioning

confidence: 99%

Long-Term Stability of Nitrifying Granules in a Membrane Bioreactor without Hydraulic Selection Pressure

Zhang

Bott

et al. 2021

Processes

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“…In the field of advanced biological nitrogen removal for mainstream wastewater treatment, efforts are merging from two research directions, that is, (a) employ anammox in mainstream to reduce 60% of energy and 100% of chemicals required in traditional biological nitrogen removal (Strous, Heijnen, Kuenen, & Jetten, 1998; Tomaszewski, Cema, & Ziembińska‐Buczyńska, 2017); and (b) employ aerobic granular sludge in mainstream for high‐rate bioreaction, bioprocess consolidation, and settleability enhancement (Kent, Bott, & Wang, 2018; Sun, Angelotti, & Wang, 2019). As a result, attempts have been made to immobilize critical microbial communities required for successful anammox in aerobic granules with the hope of future application in the continuous‐flow treatment trains of mainstream wastewater treatment.…”

Section: Introductionmentioning

confidence: 99%

“…The long‐term structural stability of aerobic granules in continuous‐flow mainstream application is another unknown. Although the slow‐growing nitrifying aerobic granules are noted for their outstanding structural stability (Liu, Yang, & Tay, 2004), almost all of the aerobic granules reported so far were cultivated in SBRs (He, Zhang, Zhang, & Wang, 2017; Wei et al, 2018), which is incompatible with the continuous‐flow nature of the mainstream wastewater treatment (Kent et al, 2018; Sun et al, 2019). Although some nitrifying granules have been studied in CFRs, the longest cultivation only lasted about 300–400 days (Bartrolí, Pérez, & Carrera, 2010; Isanta et al, 2015; Kent et al, 2018).…”

Section: Introductionmentioning

confidence: 99%

“…Although some nitrifying granules have been studied in CFRs, the longest cultivation only lasted about 300–400 days (Bartrolí, Pérez, & Carrera, 2010; Isanta et al, 2015; Kent et al, 2018). Technically, aerobic granular sludge is amenable to SBRs but not to CFRs due to the challenges in implementing feast/famine conditions and selection pressure required for aerobic granulation in the latter (Kent et al, 2018; Sun et al, 2019).…”

Section: Introductionmentioning

confidence: 99%

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Free ammonia resistance of nitrite‐oxidizing bacteria developed in aerobic granular sludge cultivated in continuous upflow airlift reactors performing partial nitritation

Kent²,

Sun

et al. 2020

Water Environment Research

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Free ammonia (FA) inhibition has been taken advantage as a strategy to suppress the growth of nitrite‐oxidizing bacteria (NOB) in aerobic granules stabilized in a continuous upflow airlift reactor to achieve partial nitritation. However, after nearly 18 months of continuous exposure of aerobic granules to FA in the reactor, the FA inhibition of NOB was proven ineffective, and the partial nitritation gradually shifted to partial nitrification even though the long‐term granule structural stability remained excellent under the continuous‐flow mode. The extent of NOB resistance to FA inhibition was quantified based on the kinetic response of NOB to various FA concentrations in the form of an uncompetitive inhibition coefficient. It was confirmed that the NOB immobilized in larger granules under longer term exposure to FA tend to become more resistant to FA. Thereby, it was concluded that NOB can develop strong resistance to FA after continuous exposure, and thus, FA inhibition is not a reliable strategy to achieve partial nitritation in mainstream wastewater treatment. Practitioner points Nitrifying aerobic granules can remain structurally stable in continuous‐flow bioreactors. NOB developed free ammonia resistance after 6‐month continuous exposure. Larger aerobic granules tended to develop stronger free ammonia resistance. Free ammonia inhibition is not a reliable strategy for mainstream anammox.

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Continuous flow reactors for cultivating aerobic granular sludge: configuration innovation, principle and research prospect

Yan

Cui

Huang

2021

J of Chemical Tech & Biotech

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Efficient start‐up, cultivation and maintenance of aerobic granular sludge (AGS) in continuous flow reactors (CFRs) is critical for its full‐scale application in wastewater treatment plants (WWTPs). The successful implementation of AGS under continuous flow condition depends on the configuration of CFR that provides the selective pressures and hydraulic shear force (HSF) to sludge required for rapid granulation. Important progress has been witnessed with respect to CFR configurations in recent decades for in‐situ granulation of aerobic sludge. This review summarized the difficulties of granulation during continuous flow, as well as the reactor configuration, granulation mechanism and the AGS characteristics, along with the future research prospects. It is of significance to promote the innovation of continuous flow configuration in order to realize the AGS application in mainstream WWTPs in the future. © 2021 Society of Chemical Industry (SCI).

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Continuous-flow aerobic granulation in plug-flow bioreactors fed with real domestic wastewater

Cited by 62 publications

References 39 publications

Long-Term Stability of Nitrifying Granules in a Membrane Bioreactor without Hydraulic Selection Pressure

Long-Term Stability of Nitrifying Granules in a Membrane Bioreactor without Hydraulic Selection Pressure

Free ammonia resistance of nitrite‐oxidizing bacteria developed in aerobic granular sludge cultivated in continuous upflow airlift reactors performing partial nitritation

Continuous flow reactors for cultivating aerobic granular sludge: configuration innovation, principle and research prospect

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