Effects of naturally occurring grit on the reactor performance and microbial community structure of membrane bioreactors

Meng, Fangang; He, Xiang

doi:10.1016/j.memsci.2015.09.015

Cited by 35 publications

(6 citation statements)

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“…The bulk and biocake solution samples of the AeMBR basically shared similar communities, and the major phyla were the Bacteroidetes and Proteobacteria, followed by Acidobacteria and Nitrospirae (Figure a). The dominance of Bacteroidetes and Proteobacteria in the bulk and biocake solutions coincided with previous reports in the literature. , The abundant Bacteroidetes (found to be carbohydrate degraders) detected might be related to the high level of glucose fed into the MBRs in our work. Within the Bacteroidetes phylum, the predominant f_Microscillaceae occupied 41.1 and 37.5% of the bulk and biocake solution samples, respectively.…”

Section: Resultssupporting

confidence: 92%

“…The dominance of Bacteroidetes and Proteobacteria in the bulk and biocake solutions coincided with previous reports in the literature. 63,64 The abundant Bacteroidetes (found to be carbohydrate degraders 65 ) detected might be related to the high level of glucose fed into the MBRs in our work. Within the Bacteroidetes phylum, the predominant f_Microscillaceae occupied 41.1 and 37.5% of the bulk and biocake solution samples, respectively.…”

Section: ■ Results and Discussionmentioning

confidence: 77%

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Micro-particles—A Neglected but Critical Cause of Different Membrane Fouling between Aerobic and Anaerobic Membrane Bioreactors

Yao

Zhou

Stuckey

et al. 2020

ACS Sustainable Chem. Eng.

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Until recently, membrane fouling in anaerobic membrane bioreactors (AnMBRs) was generally understood based on and by extrapolating from well-studied aerobic membrane bioreactors (AeMBRs). Clearly, this will probably be unhelpful, as each contains different microbial ecology, particles/colloids, and soluble microbial products. In this paper, a comprehensive comparison was made between these two systems to understand their different sources of foulants and, hence, differences in fouling. Our results showed that worse fouling occurred in the AnMBR than in the AeMBR due to the different characteristics of bulk solutions. Filtration tests revealed that the bulk solution supernatant in the AnMBR contained more abundant micro-particles (0.45−10 μm, 69.4% of the total organics), exhibiting a much higher specific filtration resistance (1.56 × 10 15 m −1 /g TSS) and a unified modified fouling index value (4.56) than the AeMBR (36.4%, 2.17 × 10 12 m −1 /g TSS and 0.03, respectively). Based on Fourier transform infrared spectra combined with principal component analysis, the AnMBR foulants had functional groups similar to those of the micro-particles in the bulk solution, while the AeMBR foulants were more similar to extracellular polymeric substances of the bulk sludge. More interestingly, the microbial source tracking calculation utilizing 16S rRNA gene sequences showed that the micro-particles were an important source (22.6%) of the biocake microorganisms in the AnMBR but only contributed to 1.9% in the AeMBR. In contrast, the bulk sludge (67.7%) was determined to be a more dominant component of the biocake microorganisms in the AeMBR than in the AnMBR (38.7%). Our findings enable us to discriminate between the different sources of foulants in AnMBRs and AeMBRs and highlight the significance of micro-particles in anaerobic systems from abiotic and biotic aspects. It is clear in AnMBRs that a more sustainable form of treatment by reducing the micro-particles could be better for fouling control.

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Section: Resultssupporting

confidence: 92%

Section: ■ Results and Discussionmentioning

confidence: 77%

Micro-particles—A Neglected but Critical Cause of Different Membrane Fouling between Aerobic and Anaerobic Membrane Bioreactors

Yao

Zhou

Stuckey

et al. 2020

ACS Sustainable Chem. Eng.

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“…These two fouling profiles followed the typical trend reported for constant flux operation of submerged porous membranes (Le-Clech et al, 2006). Meng and He (2015) 14 appeared to be fouled with a dense and rough biomass layer that acts as a support for biofilm growth.…”

Section: Effect Of Pacs On Sludge Filterabilitysupporting

confidence: 72%

Fouling control in membrane bioreactors with sewage-sludge based adsorbents

et al. 2016

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The potential application of powdered activated carbon (PAC) to mitigate membrane fouling has been tested in membrane bioreactors (MBRs) fed with cosmetic wastewater. Inexpensive powder activated carbon was prepared from sewage sludge biosolids (B-PAC) by pyrolysis (750 °C; 0.5 h) and air-activation (400 °C; 2 h). Adsorption capacities of 143 and 570 mg g were reached for carbohydrates and proteins, respectively, quite similar to those of a commercial activated carbon (C-PAC). To check the effect of PAC addition on membrane fouling, three MBRs were simultaneously operated without (control-MBR) and with PAC (B-MBR and C-MBR) for 150 days in continuous mode at 8 L m h flux. Similar COD removal efficiencies were achieved in these three MBR systems. After 100 days of operation, the effect of the PACs on the sludge filterability was studied in the MBRs for 10 days. B-MBR showed stable transmembrane pressure (TMP) after 9 days of operation, unlike of control-MBR and C-MBR, where the TMP increased after the 2nd and 5th days, respectively. Therefore, operational cost saving can be achieved in the membrane cleaning due to decrease of fouling rate. Operating at stable state condition the addition of PAC gave rise to an increase of the critical flux of 25%. In an extra shear test, carried out at the end of the continuous experiment, a clear reduction in mean size of the flocs from 45 to 28 μm was observed in control-MBR. However, the extra shear led to a slight reduction of the mean size of flocs (less than 5%) in MBRs with PAC, with average sizes of 62 and 71 μm in C-MBR and B-MBR, respectively. The molecular weight fractionation of the MBR demonstrated a higher selectivity of B-PAC toward the adsorption of proteins smaller than 1 μm which prevents the irreversible fouling of the membranes. The membranes lifetime was increased because the B-PAC extended the filtration for a longer period than C-PAC, probably due to its easier in-situ regeneration.

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“…In fact, humic substances could be easily adsorbed onto membranes due to their high hydrophobicity, which in turn induced the development of initial fouling . In general, humic substances with negative charges due to the presence of carboxyl and hydroxyl groups facilitated the deposition of hydrophilic biomolecules (e.g., proteins and polysaccharides) through the electrostatic and hydrophobic actions, causing irreversible membrane fouling. − In this work, the RDA analyses further revealed that the membrane fouling rate and pore blocking resistance were both positively related to rejected humic substances (Figure ). Therefore, it is reasonable to consider that humic substances in DOM released from the sludge suspension after contact with NaClO played a vital role in membrane fouling development.…”

Section: Resultsmentioning

confidence: 58%

Chemical Cleaning-Triggered Release of Dissolved Organic Matter from a Sludge Suspension in a Ceramic Membrane Bioreactor: A Potential Membrane Foulant

Sun

Liu

2021

ACS EST Water

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Ceramic membrane bioreactors (MBRs) have attracted a great deal of interest due to their robustness in the treatment of various kinds of wastewaters. So far, in situ chemical cleaning with sodium hypochlorite (NaClO) has been the most prevalent MBR cleaning method. This study showed that in situ NaClO cleaning in MBRs triggered a significant release of dissolved organic matter (DOM) from a sludge suspension, while the generated DOM could facilitate fouling development, especially irreversible fouling in a ceramic MBR. It was found that biopolymers with a molecular weight (MW) of >10 kDa and humic substances could be effectively rejected by the ceramic membranes. As such, the membrane fouling rate (dTMP/dt) of the supernatant from a NaClO-treated sludge suspension was closely related to the rejected levels of biopolymers and humic substances. However, hydrophobic DOM and low-MW organics (MW < 500 Da) could easily pass through the membranes, indicating an insignificant contribution to the observed membrane fouling. Consequently, this study verified the contributions of DOM released from a sludge suspension after in situ membrane cleaning with NaClO with respect to subsequent membrane fouling development in a ceramic MBR.

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Effects of naturally occurring grit on the reactor performance and microbial community structure of membrane bioreactors

Cited by 35 publications

References 50 publications

Micro-particles—A Neglected but Critical Cause of Different Membrane Fouling between Aerobic and Anaerobic Membrane Bioreactors

Micro-particles—A Neglected but Critical Cause of Different Membrane Fouling between Aerobic and Anaerobic Membrane Bioreactors

Fouling control in membrane bioreactors with sewage-sludge based adsorbents

Chemical Cleaning-Triggered Release of Dissolved Organic Matter from a Sludge Suspension in a Ceramic Membrane Bioreactor: A Potential Membrane Foulant

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