Investigating Membrane Biofouling from perspectives of Bacterial Size and Shape, using Field-Flow Flow Fractionation

Transcription

1 1/29 Investigating Membrane Biofouling from perspectives of Bacterial Size and Shape, using Field-Flow Flow Fractionation Eunkyung Lee, Sungyun Lee, Jihee Moon, Suhan Kim, Jaeweon Cho* NOM ecology laboratory Gwangju Institute of Science and Technology (GIST)

2 Contents 2/ Introduction and Objectives Backgrounds Methods and Materials Results and Discussions Membrane Characteristics Bacteria Characteristics Results from FlFFF analysis Conclusions

3 Introduction and Objectives 3/29

4 Introduction 4/28 Biofouling, resulted from the deposition of bacteria on the membrane surface and concomitant extra cellular substances, can be problematic in effective membrane process operation. (Chee et al., (2005) Environ. Sci. Technol. 39, ) Bacteria have been known to differently affect on membrane biofouling depending on their hydrophobicity and surface charge. (Loosdrecht et al., (1987) Appl. Environ. Microbial. 53, 8, ) Ref : Expert Rev. Anti-infect. Ther. 1(4), (2003) A cake of E. coli on the surface of a membrane (G.L. Leslie et al., 1993)

5 Introduction 5/28 Flow Field-Flow Flow Fractionation (FlFFF( FlFFF) Characterization tool for various solutes An ideal model of crossflow membrane filtration Easy to predict interactions between membrane and solute Channel flow Membrane as an accumulation wall retention time (Moon et al., 2005, Desalination)

6 Objectives 6/28 To fractionate three different bacteria having different properties including size and shape with various membranes by flow field-flow flow fractionation (FlFFF( FlFFF). To determine the bacterial size from the obtained retention time distribution of each bacteria. To predict biofouling quantitatively using flow field-flow flow fractionation (FlFFF( FlFFF).

7 7/29 Backgrounds and Literature Reviews

8 Background 8/28 Related Theories with Bacteria Characteristics Bacterial adhesion Non-specific adhesion Specific adhesion Reversible physical phase Irreversible molecular phase - Van der Waals and electrostatic forces - The long-range interactions (distances > 150 nm) based on the distance and free energy - Originated from the formation of a chemical combination - The short-range interactions (distances <3 nm) based on the chemical bonds, ionic and dipole interactions and hydrophobic interactions (Busscher et al., 1992; An et al., 1997)

9 Background 9/28 Related Theories with Bacteria Characteristics Bacteria are generally negative-charged due to the functional groups such as carboxyl (-COOH),( amino (-NH( NH2), and hydroxyl (-OH) from cell wall components. (Sharma et al., Colloids and surfaces B: biointerfaces,, 2003) An increase of ionic strength in the carrier solution reduces the repulsive interaction between bacteria cells and membrane. Bacterial adsorption on membrane surface (Lee et al., Analytical chemistry, 2003) - Effect of bacterial hydrophobicity Hydrophilic/hydrophobic bacteria prefer the hydrophilic/hydrophobic surface,, respectively (An et al., J of biomedical materials research part B, 1997) Effect of bacteria morphology on membrane biofouling??

10 Background 10/28 Related Theories with Flow Field-Flow Flow Fractionation (a) Normal mode Field-driven transport (a) Channel flow Diffusion-driven transport Membrane as an accumulation wall Brownian-induced diffusion dominant D = kt 6πμ a (b) Hyperlayer mode Channel flow For bacteria analysis Field-driven transport (b) Diffusion-driven transport Membrane as an accumulation wall Shear-induced diffusion dominant D s = ' D γa 2

11 Methods and Materials 11/29

12 Methods and materials: Bacteria 12/28 Bacteria Shape Sphere type (Bacteria were purchased from KCTC) Rod type Size 0.5 μm 1.5 μm 2.5 μm Bacteria Staphylococcus epidermidis Escherichia. coli Flavobacterium lutescens Characteristics Hydrophylic/ hydrophobic property Surface charge Methods Contact angle Zeta potential Equipments Contact Angle goniometer, Rame-hart, USA Electrophoresis analyser, ELS-8000, Otsuka Electronics, Japan Size TEM image JEM 2100, JEOL, Japan

13 Methods and materials: Membrane 13/28 Membranes Manufacturer Materials NE70 Saehan Piperazine based polyamide TFC GM Osmonics Sulfonated polyethersulfone Characteristics Hydrophylic/ hydrophobic property Surface charge Pore size distribution Method Contact angle Zeta potential HPLC Equipment Contact Angle goniometer, Rame-hart, USA Electrophoresis analyser, ELS-8000, Otsuka Electronics, Japan Column (Ultrahydrogel( 120,Waters, MA) Refractive index detector PEG standard (Aldrich) Roughness AFM XE-1000, PSIA, Korea Size SEM image S-4700, Hitachi, Japan

14 Methods and materials : FlFFF 14/28 Asymmetric field flow fractionation (HRFFF Series, Postnova, Germany) 1.4 cm 27.5 cm Thickness: 250 μm Schematic diagram of the asymmetric FlFFF Channel flow rate Cross flow rate Detectors Carrier solution 1.5 ml/min 0.1 ml/min UV spectrometer at 600 nm DI water mm NaN 3 (11~13 μs/cm) 10 mm KCl mm NaN 3 (1,484 μs/cm) 0.01 % FL mm NaN 3 (20~22 μs/cm)

15 Results and Discussions 15/29

16 Results: Membrane characteristics 16/28 Membranes NE70 GM Materials Piperazine based polyamide TFC Sulfonated polyethersulfone MWCO (Da) Zeta potential At ph7 (mv) , Membrane characteristics: Pore size distribution, zeta potential NE70 GM Zeta potential (mv) GM NE Relative Molecular Mass Relative Molecular Mass ph

17 Results: Membrane characteristics 17/28 Roughness image of membrane surface by AFM : a) GM, b) NE70 (a) (b) `SEM image of membrane surface : a) GM, b) NE70 (a) (b) (c) Membranes Roughness (nm) Contact angle ( º) R * a R ** q Water a) Formamide a) Diiodomethane b) NE GM * Ra: arithmetic average roughness measured by AFM ** Rq: root-mean-squared roughness measured by AFM a) polar component b) non-polar component

18 Results: Bacteria Characteristics 18/28 TEM image of each bacteria Staphylcoccus epidermidis 0.5 μm Escherichia coli 0.5 μm Flavobacterium lutescens 1.5 μm 0.5 μm 2.5 μm Surface charge of bacteria Contact angle of bacteria Zeta potential (mv) ph Flavobacterium lutescens Staphylococcus epidermidis E. coli Staphylococcus aureus Flavobacterium lutescens Escherichia coli water foramide Diiodomethane

19 Results: Standard particles from FlFFF 19/28 Results with standard particle μ m μ m UV intensity (V) μ m 0.43 μ m Retention time (sec) Figure. Retention time distribution of standard particles from FlFFF with GM membrane using 0.01% FL-70 as a carrier solution Reference particle: Polystyrene latex microsphere suspensions (Duke Scientific Corp., USA)

20 Results: Standard particles from FlFFF 20/28 Results with standard particle Particle size (μ m) (a) 0.01% FL-70 DI water 10mM KCl Particle size (μm) (b) 0.01% FL-70 DI water 10mM KCl Retention time at peak maximum (sec) Retention time at peak maximum (sec) Maximum Retention time of standard particles with various carrier r solution from FlFFF : (a) GM membrane, (b) NE70 membrane

21 Results: Bacteria with FlFFF 21/28 Relationship between the bacterial size and retention time in FlFFF μm 1.5 μm 2.5 μm μm Retention time (sec) S. epidermidis 1.5 μm E. coli F. lutescens 3.0 μm Standard particle Bacteria S. epidermidis E. coli F. lutescens Z eta potential (m V ) Size ( μm ) ph Flavobacterium lutescens Staphylococcus epidermidis E. coli Staphylococcus aureus Figure. Comparison of maximum peak retention time with bacteria and standard particles (GM membrane with DI water).

22 UV intensity (V) UV intensity (V) UV intensity (V) Results: Bacteria with FlFFF NE Low fouling potential R etention tim e (sec) R etention tim e (sec) R etention tim e (sec) High 0.01% FL-70 E. coli S. epiderm idis Flavobacterium DI water 10 m M K Cl Flavobacterium sp. S. epiderm idis E. coli Effect of surfactant Reduction of retention time Coating effect on the membrane surface by surfactant Effect of high ion strength Increase of retention time Broad peak Reduction of the electrostatic repulsion due to double layer compaction 22/28 Effect of DI water Slightly delayed than the surfactant condition High potential of membrane biofouling especially in high ionic strength condition

23 Results: Bacteria with FlFFF fouling potential 23/28 Effect of surfactant and DI water on GM GM Low High Relatively fast fractionation Low possibility of membrane biofouling in GM than NE70 UV intensity (V) % FL-70 E. coli S. epiderm idis Flavobacterium sp. S. aureus Contrary to the NE70 results caused by hydrophilic/hydrophobic interaction b/w bacteria and membrane UV intensity (V) Retention tim e (sec) D I w a t e r S. aureus E. c o li F lavobacterium sp. S. epiderm idis Effect of high ion strength Increase of retention time Broad peak Reduction of the electrostatic repulsion due to double layer compaction UV intensity (V) R eten tio n tim e (sec) 10 m M K C l R etention tim e (sec)

24 Results: Bacteria with FlFFF 24/28 Brief summary FlFFF was effectively used to fractionate the bacteria in order to investigate the membrane fouling. Similar to the previous researches, it was revealed that bacteria affect on membrane biofouling depending on the ionic strength and hydrophobicity. Carrier solution Surfactant DI water KCl solution Retention time results in FlFFF no interaction Slightly delayed significantly delayed Biofouling potential Low Medium High

25 Results: Bacteria with FlFFF 25/28 Bacterial size evaluation by FlFFF using GM membrane with 0.01 % FL70 Particle size (μm) GM membrane, 0.01% FL70 S. aureus E. coli Flavobacterium S. epidermidis TEM image Size from TEM image (μm) Size from FlFFF (μm) S. epidermidis E. Coli Flavobacterium lutescens Retention time (sec)

26 Results: Bacteria with FlFFF 26/28 Aggregation of bacteria Estimation of hydrodynamic bacterial size Live bacteria vs. dead bacteria

27 Conclusions 27/28 It was revealed that bacteria could be successfully fractionated using FlFFF. FlFFF was examined as an effective tool which can suggest a potential of bacterial membrane biofouling. As already shown in previous studies, retention of bacteria in FFF channel was significantly influenced by ionic strength. Size of bacteria proved from FFF was slightly different with the size from TEM image. Further study will be proceeded with actual batch scale membrane test to compare with the FFF results.

28 Acknowledgement 28/28 This research was supported by a grant (No. R0A ) from the National Research Laboratory Program of the Korea Science and Engineering Foundation (KOSEF). Thank you! Presenter : Eunkyung Lee, storyhil@gist.ac.kr Advisor : Jaeweon Cho, jwcho@gist.ac.kr