Passage of soft pathogens through microfiltration membranes scales with transmembrane pressure

Helling, Alexander; Kubicka, Alexander; Schaap, Iwan A. T.; Polakovič, Milan; Hansmann, Björn; Thiess, Holger; Strube, Jochen; Thom, Volkmar

doi:10.1016/j.memsci.2016.08.016

Cited by 33 publications

(15 citation statements)

References 39 publications

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“…Gram-negative bacteria were also demonstrated to cross through membrane barriers by deforming themselves under high filtration pressures of 10 to 950 kPa 48,49 . Earlier study has also shown that the particle size in the cake layer from anaerobic membranes decreases from the top to the bottom layer, resulting in a corresponding decrease in porosity across the different layers 50,51 .…”

Section: Discussionmentioning

confidence: 99%

Removal of Antibiotic-Resistant Bacteria and Antibiotic Resistance Genes Affected by Varying Degrees of Fouling on Anaerobic Microfiltration Membranes

Cheng

Hong

2017

Environ. Sci. Technol.

111

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An anaerobic membrane bioreactor was retrofitted with polyvinylidene fluoride (PVDF) microfiltration membrane units, each of which was fouled to a different extent. The membranes with different degrees of fouling were evaluated for their efficiencies in removing three antibiotic-resistant bacteria (ARB), namely, bla-positive Escherichia coli PI-7, bla-positive Klebsiella pneumoniae L7, and bla-positive E. coli UPEC-RIY-4, as well as their associated plasmid-borne antibiotic resistance genes (ARGs). The results showed that the log removal values (LRVs) of ARGs correlated positively with the extent of membrane fouling and ranged from 1.9 to 3.9. New membranes with a minimal foulant layer could remove more than 5 log units of ARB. However, as the membranes progressed to subcritical fouling, the LRVs of ARB decreased at increasing operating transmembrane pressures (TMPs). The LRV recovered back to 5 when the membrane was critically fouled, and the achieved LRV remained stable at different operating TMPs. Furthermore, characterization of the surface attributed the removal of both the ARB and ARGs to adsorption, which was facilitated by an increasing hydrophobicity and a decreasing surface ζ potential as the membranes fouled. Our results indicate that both the TMP and the foulant layer synergistically affected ARB removal, but the foulant layer was the main factor that contributed to ARG removal.

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Section: Discussionmentioning

confidence: 99%

Removal of Antibiotic-Resistant Bacteria and Antibiotic Resistance Genes Affected by Varying Degrees of Fouling on Anaerobic Microfiltration Membranes

Cheng

Hong

2017

Environ. Sci. Technol.

111

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“…[80][81][82] The bacterial cell wall can be elastic and deform under pressure or become less rigid dependent on the environment, such as the presence of antibiotics. [83][84][85] The presence of foulant is known to improve the removal of extracellular DNA containing ARGs and ARB, 49 which most likely led to the variability of the microbial community and differential removal of ARGs found in the final filtrate. Optimization of the control of the level of foulant could improve ARB and ARG removal.…”

Section: Enumeration Of 16s Rrna Genesmentioning

confidence: 99%

Removal of antibiotic resistance genes in an anaerobic membrane bioreactor treating primary clarifier effluent at 20 °C

Kappell

Kimbell

Seib

et al. 2018

Environ. Sci.: Water Res. Technol.

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Anaerobic membrane bioreactors (AnMBR) play a key role in future plans for sustainable wastewater treatment and resource recovery because they have no energy-intensive oxygen transfer requirements and can produce biomethane for renewable energy. Recent research results show that they can meet relatively stringent discharge limits with respect to BOD 5 and TSS when treating municipal wastewater primary effluent. Sustainable used water recovery plans should also consider removal of unregulated pollutants. Antibiotic resistance genes (ARGs) represent an important emerging contaminant due to public health concerns surrounding the spread of infections resistant to common antibiotics. Conventional activated sludge processes have demonstrated mixed results regarding ARG removal. The objective of this research was to determine the impact of an AnMBR on ARG removal when treating municipal primary clarifier effluent at 20°C. AnMBR treatment resulted in 3.3 to 3.6 log reduction of ARG and the horizontal gene transfer determinate, intI1, copies in filtrate. Membrane treatment significantly decreased the total biomass as indicated by a decrease in 16S rRNA gene concentration. Microbial community analysis via Illumina sequencing revealed that the relative abundance of putative pathogens was higher in membrane filtrate compared to primary effluent although the overall bacterial 16S rRNA gene concentrations was lower in filtrate. Membrane treatment also substantially reduced microbial diversity in filtrate compared to anaerobic reactor contents.Mainstream anaerobic wastewater treatment is a promising technology for sustainable water resource recovery. Anaerobic membrane bioreactors (AnMBRs) can meet relatively stringent BOD 5 and TSS regulatory standards (BOD 5 <10 mg L −1 , TSS <10 mg L −1 ) for municipal wastewater at temperatures as low as 10°C. The research reported herein demonstrated that AnMBR technology can also significantly reduce antibiotic resistance gene copies.

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“…However, recent studies demonstrated that bacterial transfer through the membrane structure takes place during filtration operations, even if the pore size is significantly smaller than the bacteria cell size at rest in suspension [2][3][4][5][6][7][8]. Several reasons were put forward to explain these bacteria leaks through the membrane: firstly, the presence of defects in the membrane structure which appear during the membrane manufacture or ageing [9]; secondly, the biological nature of the filtered particles confers them the fitness to override the size-based selectivity mechanism.…”

Section: Introductionmentioning

confidence: 99%

“…Effectively, in the specific case of bacteria filtration, the cell size of the microorganisms is not the only parameter which determines the transfer through the membrane [10]. Recent works demonstrated that the shape of the bacteria cell [3] and the Gram type [7,8], which characterize the cell wall composition, are also important parameters that play a key role in the particle retention. The main part of bacteria species is classified as Gram-positive or Gram-negative according to their cell wall structure.…”

Section: Introductionmentioning

confidence: 99%

“…The cell envelope of Grampositive bacteria corresponds to a thick layer of peptidoglycan (crosslinked polymer) exposed outside of the cell membrane, whereas Gramnegative bacteria present a thin layer of peptidoglycan located between the cell membrane and the outer membrane (description available in a dedicated study [11]). This difference in structure, composition and organization of the cell wall and more specifically, the thickness of the peptidoglycan layer can lead to different retention rates during filtration tests: Gram-positive bacteria exhibiting a thicker peptidoglycan layer, are less deformable, and as a consequence, present higher retention rates [7,8].…”

Section: Introductionmentioning

confidence: 99%

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Bacteria transfer by deformation through microfiltration membrane

Gaveau

Coetsier

Roques

et al. 2017

Journal of Membrane Science

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Living particles such as bacteria are able to transfer through membrane pores that are smaller than cell size due to the specific stiffness of this type of microorganism. This phenomenon can lead to a significant loss of selectivity in the filtration process, which is a major cause of concern in the sterilizing filtration step. This study investigates the retention of three bacteria strains: Escherichia coli CIP 54124, Pseudomonas aeruginosa CIP 103467 and Staphylococcus aureus CIP 53154 by model porous membranes for various operating conditions (transmembrane pressure, feed concentration and the physicochemical composition of filtered media with antibacterial agent added at sublethal concentration). The first part of this study is dedicated to defining the size and the nanomechanical properties of the envelope of the studied bacteria by microscopic techniques (Transmission electron microscopy & Atomic-force microscopy), in order to then explore the role of these quantifiable characteristics on the cell transfer through the pores by deformation mechanisms. Our results lead to the development of a numerical model to connect the observed retention efficiency of the filtration experiment and the microscopic information about individual particles.

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Passage of soft pathogens through microfiltration membranes scales with transmembrane pressure

Cited by 33 publications

References 39 publications

Removal of Antibiotic-Resistant Bacteria and Antibiotic Resistance Genes Affected by Varying Degrees of Fouling on Anaerobic Microfiltration Membranes

Removal of Antibiotic-Resistant Bacteria and Antibiotic Resistance Genes Affected by Varying Degrees of Fouling on Anaerobic Microfiltration Membranes

Removal of antibiotic resistance genes in an anaerobic membrane bioreactor treating primary clarifier effluent at 20 °C

Bacteria transfer by deformation through microfiltration membrane

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