Effects of Wash-Out Dynamics on Nitrifying Bacteria in Aerobic Granular Sludge During Start-Up at Gradually Decreased Settling Time

Szabo, Enikö Barbara; Hermansson, Malte; Modin, Oskar; Persson, Frank; Wilén, Britt‐Marie

doi:10.3390/w8050172

Cited by 37 publications

(19 citation statements)

References 28 publications

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“…However, it was shown before that nitrification can be the main pathway for ammonium removal even at low relative abundances of AOB and NOB (Szabó et al, 2016). Furthermore, AOB were detected by FISH-CLSM in all three reactors along the biomass-water interfaces (including channels) where the availability of oxygen is highest ( Figure 3 ).…”

Section: Resultsmentioning

confidence: 99%

Microbial Population Dynamics and Ecosystem Functions of Anoxic/Aerobic Granular Sludge in Sequencing Batch Reactors Operated at Different Organic Loading Rates

et al. 2017

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The granular sludge process is an effective, low-footprint alternative to conventional activated sludge wastewater treatment. The architecture of the microbial granules allows the co-existence of different functional groups, e.g., nitrifying and denitrifying communities, which permits compact reactor design. However, little is known about the factors influencing community assembly in granular sludge, such as the effects of reactor operation strategies and influent wastewater composition. Here, we analyze the development of the microbiomes in parallel laboratory-scale anoxic/aerobic granular sludge reactors operated at low (0.9 kg m −3 d −1 ), moderate (1.9 kg m −3 d −1 ) and high (3.7 kg m −3 d −1 ) organic loading rates (OLRs) and the same ammonium loading rate (0.2 kg NH 4 -N m −3 d −1 ) for 84 days. Complete removal of organic carbon and ammonium was achieved in all three reactors after start-up, while the nitrogen removal (denitrification) efficiency increased with the OLR: 0% at low, 38% at moderate, and 66% at high loading rate. The bacterial communities at different loading rates diverged rapidly after start-up and showed less than 50% similarity after 6 days, and below 40% similarity after 84 days. The three reactor microbiomes were dominated by different genera (mainly Meganema, Thauera, Paracoccus, and Zoogloea), but these genera have similar ecosystem functions of EPS production, denitrification and polyhydroxyalkanoate (PHA) storage. Many less abundant but persistent taxa were also detected within these functional groups. The bacterial communities were functionally redundant irrespective of the loading rate applied. At steady-state reactor operation, the identity of the core community members was rather stable, but their relative abundances changed considerably over time. Furthermore, nitrifying bacteria were low in relative abundance and diversity in all reactors, despite their large contribution to nitrogen turnover. The results suggest that the OLR has considerable impact on the composition of the granular sludge communities, but also that the granule communities can be dynamic even at steady-state reactor operation due to high functional redundancy of several key guilds. Knowledge about microbial diversity with specific functional guilds under Granular Microbiome at Different Organic Loads different operating conditions can be important for engineers to predict the stability of reactor functions during the start-up and continued reactor operation.

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Section: Resultsmentioning

confidence: 99%

Microbial Population Dynamics and Ecosystem Functions of Anoxic/Aerobic Granular Sludge in Sequencing Batch Reactors Operated at Different Organic Loading Rates

et al. 2017

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“…As the density is defined as the mass per volume AGS, the density is increased by the salinity, which in turn affects the settling velocity [32]. This finding may also be explained by the aforementioned increase in the MLSS, and by the selection pressure operating strategy, where a short sedimentation time (10 min) was maintained to accelerate the microbial aggregation and to continuously discharge sludge with poor settling characteristics [86][87][88]. Fig.…”

Section: Mlss and Sv I30mentioning

confidence: 97%

The effects of high salinity on nitrogen removal and the formation characteristics of aerobic granular sludge

Kim

Ahn

2019

Environmental Engineering Research

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This study investigated the biological treatment of high-salinity wastewater using aerobic granular sludge (AGS). The removal performance, AGS characteristics, and microbial community were examined under salinity conditions ranging from 0.5 to 3.0 wt.%. When the salinity was increased, the removal efficiency of the chemical oxygen demand did not change substantially. The mean removal efficiency of NH4+-N ranged from 43.7 to 72.6% during the operation period. As for the concentration of extracellular polymeric substances (EPS), the polysaccharide/protein (PS/PN) ratio increased from 0.37 to 0.57. The concentrations of the mixed liquor suspended solid (MLSS) and mixed liquor volatile suspended solid (MLVSS) were 4,560 and 3,170 mg/L, respectively, in the end phase, and the MLVSS/MLSS ratio decreased from 0.81 to 0.69. The sludge volume index (SVI30) decreased linearly from 88 to 58 mL/g. In the microbial community analysis, Nitrosomonas species accounted for 22.9% of the total bacteria in the initial phase, whereas Halomonas accounted for 43.2% in the end phase. Hence, the gradually increased salinity appears to facilitate the dominance of halophilic microorganisms in the long-term operation of an AGS-based biological treatment system and the stable retention of AGS.

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“…The reactor was mounted with sampling port for collecting water and analysis and diffuser. The treated water was discharged through reactor middle port to apply volume exchange rate (VER) of 50% [41][42][43]. Table 2 shows the operation condition of the laboratory-scale SBR.…”

Section: Reactor and Experimental Set-upmentioning

confidence: 99%

Effects of carbon to nitrogen ratio on the performance and stability of aerobic granular sludge

Kim

Ahn

2020

Environmental Engineering Research

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The purpose of this study was to assess the nutrient salts removal efficiency and stability of the aerobic granular sludge (AGS) by change in C/N (carbon to nitrogen) ratio. The laboratory-scale experiments were performed to analyze the removal efficiencies for organic matter and contents of nitrogen, MLSS, sludge volume index, and extracellular polymeric substances (EPS) under C/N ratio conditions of 5.0, 10.0, 15.0, and 20.0. The microorganisms were observed using optical microscope and the microbial communities were analyzed using pyrosequencing. The increase in C/N ratio from 5.0 to 20.0 increased the organic matter and nitrogen removal efficiency to 95.9 and 79.1%, respectively. For the EPS contents, an influencing factor of granule stability, the polysaccharides to protein (PS/PN) ratio increased from 0.55 to 0.79. For the microbial community, the Thauera was the most common genus in ending phase occupying 63.7%. This microorganism is regarded as one contributing to organic matter degradation and improved production of EPS including AGS of microorganism, thus, may be an explanation of the results of this study such as increase in organic material in AGS and improvement of denitrification efficiency and contents of EPS with increase in C/N ratio.

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Effects of Wash-Out Dynamics on Nitrifying Bacteria in Aerobic Granular Sludge During Start-Up at Gradually Decreased Settling Time

Cited by 37 publications

References 28 publications

Microbial Population Dynamics and Ecosystem Functions of Anoxic/Aerobic Granular Sludge in Sequencing Batch Reactors Operated at Different Organic Loading Rates

Microbial Population Dynamics and Ecosystem Functions of Anoxic/Aerobic Granular Sludge in Sequencing Batch Reactors Operated at Different Organic Loading Rates

The effects of high salinity on nitrogen removal and the formation characteristics of aerobic granular sludge

Effects of carbon to nitrogen ratio on the performance and stability of aerobic granular sludge

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