11. Antony RealTimeMonitoringVirus
Content
New technique for validation of UF
membrane processes
Alice Antony and Greg Leslie
Overview
• Background
• Project outline
• Results
•
•
Nanoparticles development
UF challenge tests
• Conclusions & Future Work
Membrane validation
What is membrane validation?
Process of demonstrating that the system can produce water of the required
microbial quality under defined operating conditions and the system can be
monitored in real time assure the water quality objectives are continuously
met.
How is this performed?
Through challenge test and operational integrity monitoring tests.
What guidance do we have?
1. Membrane filtration guidance manual (MFGM)1
2. Guidelines for validating treatment processes for pathogen reduction –
Supporting Class A recycled water schemes in Victoria2
1MFGM,
USEPA, 2005
2Department
of Health, Victorian Government, February 2013
New techniques for real time monitoring of membrane
integrity for virus removal - Project outline
Phase 1 - Review of literature, identification of
knowledge gaps and recommendation of novel
integrity tests (completed in 2009)
Critical Reviews in Environmental Science and Technology 42(9), 2012, 891-933.
Phase 2 – Development and testing of novel
integrity test (Completed in 2013)
Journal of Membrane Science 454, 2014, 193-199
Phase – 1 outcomes / Phase – 2 Objectives
o Challenge test using MS2 bacteriophage, by plaque forming unit
enumeration, PFU is presently considered the best process indicator for
virus removal. However, the MS2 bacteriophage challenge test is difficult in
on a full scale plant on a regular basis1 (for revalidation)
•
Developing a non-microbial indicator for challenge testing and challenge
testing on ultrafiltration membranes
o Existing integrity test methods are for breaches ≤ 1 µm; Identifying direct or
indirect integrity testing for detecting breaches less than virus-sized
particles (0.01 – 0.04 µm)is a necessary
•
Testing size exclusion chromatography and fluorescent spectroscopy for
their sensitivity to detect membrane breaches in UF and RO membranes
1Water
Research, 2002, 36(17): 4227-4234
• Ablity to cultivate in high concentration
• sensitivity as high as 6LRV
• Impractical in full scale – high cost and effort
• Long turnover time, 24 h
• Physicochemical retention vs. inadvertent biological inactivation
Particle aggregation may enhance the filtration capacity
• PFU does not provide tools to control denaturation and aggregation
1Journal
Hep A
Norwalk
MS2 as a surrogate1,2,3 – Why and Why not?
Rotavirus
Testing with native Viruses (NV)
• Low conc. in real scenario
• Assay of NV is complex, time consuming, definite analysis
methodology is not available in some cases
• Issue of possible contamination
Poliovirus
MS2 challenge testing
of Applied Microbiology , 2007, 103(5): 1632-1638, 2Journal of Membrane Science, 2009, 326(1): 111-116
3Critical Reviews in Environmental Science and Technology, 2012, 42,891-933.
Non-microbial alternative
MS2 Phage
Non-microbial substitute
Citrate stabilized
silver (zerovalent)
nanoparticle
Diameter – 24 nm
Icosahedral
Isoelectricpoint (pI) - 3.5-3.9, net
negative change above pH 3.9
Virus sized
Spherically shaped
Negatively charged at pH 7
Stable during filtration
Synthesis of nanoparticles
Silver nitrate solution
Boil
1% sodium
citrate solution
423 nm
Constant stirring for 1 hr)
spherical or roughly
spherical silver
nanoparticles1,2
Centrifuge, redisperse in water
1The
2The
Journal of Physical Chemistry B, 107 (2003) 6269-6275.
Journal of Chemical Physics, 116 (2002) 6755-6759.
Characterisation of Nanoparticles
concentration, size, charge & stability
Concentration of the finished
nanoparticles – Inductively
coupled plasma – Optical
emission spectroscopy
Size - as average
hydrodynamic size & charge by
a dynamic light scattering,
Brookhaven 90 Plus particle
sizer
Eff. diameter (hydrated) : 50 nm
Charge: -25 mV (negatively charged)
Particle properties stable over 3 days
Characterisation of Nanoparticles
Transmission electron microscopy
• Near spherical shape, size ranging from 20 – 50 nm
• Crystal lattice pattern, d-spacing of 0.24 nm, characteristic of zerovalent
silver
Challenge testing
• Membrane - PVDF, UF membranes, average pore size - 0.04 µm
• Effective membrane area - 0.025 m2
• Flux - 30 or 50 L m-2 h-1
• Feed solution – Clean water with 5, 10 & 20 mg L-1 of silver
nanoparticles
• Parameters measured and/or compared – Clean water flux, TMP
• Change in TMP as a function of time, due t fouling of nanoparticles
Challenging compromised membranes with nanoparticles
• Physical compromise through punctures and cuts
SEM images
of the
punctures
made with a
100 µm
diameter
needle
• Chemical damage
o Exposure to hypochlorite solutions (Ct) of 2,500, 5,000, 10,000,
15,000 and 20,000 mg L-1.h
o Equivalent to a total exposure of 3.5, 6.9, 13.9, 20.8 and 27.8
months at 1mg/L concentration over multiple uses
Challenge testing contd.,
LRV and TMP change during the testing of intact UF membrane
Flux,
(L m2 h-1)
Nanoparticle
concentration,
(mg L-1 of Ag)
LRV
30
30
30
50
50
50
5
10
20
5
10
20
2.34±0.09
2.61±0.10
2.94±0.09
2.31±0.10
2.61±0.10
2.83±0.10
-0.3
0.5
0.5
0.0
0.5
0.3
• LRV ranging from 2.3 to 2.9 was demonstrated without any impact on the
operating flux
• Slightly high LRV could be established with high nanoparticle concentration
Challenge testing contd.,
• One puncture,
compromise ratio was
0.00003% and the LRV
decreased from 2.8 to 1.5
• Four successive holes, the
LRVs reduced to 1.1, 0.6,
0.5 and 0.3, respectively
• After three cuts, rejection
was 7.1 % and LRV <0.1
Challenge testing contd.,
• Realistic representation of the
impairment taking place in an
operational plant with routine
use of chemicals
• At 2500 and 5000 mg L-1.h, the
membrane resistance (Rm)
decreased to 19 and 38%, but
the rejection capacity was
almost unaffected
• Exposure to high concentrations
seem to affect both the
resistance and rejection
Summary MS2 vs silver nanoparticles
Criterion
Microbial indicators, bacteriophages
Analysis, lead
time
Long, 24 h to measure the integrity
breach
Citrate stabilised silver
nanoparticles
Small, using onsite measurement
techniques
Generation
labour intensive, needs PC2
Relatively low labour requirements
Plant
Preparation
High levels of disinfection of sample
points and preventative measures to
avoid contamination
Non-microbial, very little risk of
contamination by outside sources
Safety/hazards
Host bacteria require microbial safety
procedures
Minimal PPE
Background
interference
Potential chances of interference from
background virus and bacteria
Low Ag conc. In background
Measurement
limitations
PFU method may suffer from limitations
due to viral aggregation
No known limitations
Indicator
rigidity
Potential to deform under high pressure
and pass through the membrane
Unlikely to deform under high
pressure
4 Key Conclusions
• Demonstrated the suitability of new
citrate stabilised silver nanoparticles as
virus surrogates in terms of shape, size,
rigidity, charge and ease of detection
• Demonstrated close to 3 LRV of virus
removal for intact UF membranes
• Demonstrated the sensitivity of the
system to differentiate intact membrane
fibres from those with a low number of
physical breaches or chemical
degradation
• Demonstrated the potential for the
validation of UF membranes in recycled
water applications
Project is complete…..however..
Would like to work
• with a water utility to use these particles in
the field
• on the recovery of silver nanoparticles
Acknowledgements
membrane processes
Alice Antony and Greg Leslie
Overview
• Background
• Project outline
• Results
•
•
Nanoparticles development
UF challenge tests
• Conclusions & Future Work
Membrane validation
What is membrane validation?
Process of demonstrating that the system can produce water of the required
microbial quality under defined operating conditions and the system can be
monitored in real time assure the water quality objectives are continuously
met.
How is this performed?
Through challenge test and operational integrity monitoring tests.
What guidance do we have?
1. Membrane filtration guidance manual (MFGM)1
2. Guidelines for validating treatment processes for pathogen reduction –
Supporting Class A recycled water schemes in Victoria2
1MFGM,
USEPA, 2005
2Department
of Health, Victorian Government, February 2013
New techniques for real time monitoring of membrane
integrity for virus removal - Project outline
Phase 1 - Review of literature, identification of
knowledge gaps and recommendation of novel
integrity tests (completed in 2009)
Critical Reviews in Environmental Science and Technology 42(9), 2012, 891-933.
Phase 2 – Development and testing of novel
integrity test (Completed in 2013)
Journal of Membrane Science 454, 2014, 193-199
Phase – 1 outcomes / Phase – 2 Objectives
o Challenge test using MS2 bacteriophage, by plaque forming unit
enumeration, PFU is presently considered the best process indicator for
virus removal. However, the MS2 bacteriophage challenge test is difficult in
on a full scale plant on a regular basis1 (for revalidation)
•
Developing a non-microbial indicator for challenge testing and challenge
testing on ultrafiltration membranes
o Existing integrity test methods are for breaches ≤ 1 µm; Identifying direct or
indirect integrity testing for detecting breaches less than virus-sized
particles (0.01 – 0.04 µm)is a necessary
•
Testing size exclusion chromatography and fluorescent spectroscopy for
their sensitivity to detect membrane breaches in UF and RO membranes
1Water
Research, 2002, 36(17): 4227-4234
• Ablity to cultivate in high concentration
• sensitivity as high as 6LRV
• Impractical in full scale – high cost and effort
• Long turnover time, 24 h
• Physicochemical retention vs. inadvertent biological inactivation
Particle aggregation may enhance the filtration capacity
• PFU does not provide tools to control denaturation and aggregation
1Journal
Hep A
Norwalk
MS2 as a surrogate1,2,3 – Why and Why not?
Rotavirus
Testing with native Viruses (NV)
• Low conc. in real scenario
• Assay of NV is complex, time consuming, definite analysis
methodology is not available in some cases
• Issue of possible contamination
Poliovirus
MS2 challenge testing
of Applied Microbiology , 2007, 103(5): 1632-1638, 2Journal of Membrane Science, 2009, 326(1): 111-116
3Critical Reviews in Environmental Science and Technology, 2012, 42,891-933.
Non-microbial alternative
MS2 Phage
Non-microbial substitute
Citrate stabilized
silver (zerovalent)
nanoparticle
Diameter – 24 nm
Icosahedral
Isoelectricpoint (pI) - 3.5-3.9, net
negative change above pH 3.9
Virus sized
Spherically shaped
Negatively charged at pH 7
Stable during filtration
Synthesis of nanoparticles
Silver nitrate solution
Boil
1% sodium
citrate solution
423 nm
Constant stirring for 1 hr)
spherical or roughly
spherical silver
nanoparticles1,2
Centrifuge, redisperse in water
1The
2The
Journal of Physical Chemistry B, 107 (2003) 6269-6275.
Journal of Chemical Physics, 116 (2002) 6755-6759.
Characterisation of Nanoparticles
concentration, size, charge & stability
Concentration of the finished
nanoparticles – Inductively
coupled plasma – Optical
emission spectroscopy
Size - as average
hydrodynamic size & charge by
a dynamic light scattering,
Brookhaven 90 Plus particle
sizer
Eff. diameter (hydrated) : 50 nm
Charge: -25 mV (negatively charged)
Particle properties stable over 3 days
Characterisation of Nanoparticles
Transmission electron microscopy
• Near spherical shape, size ranging from 20 – 50 nm
• Crystal lattice pattern, d-spacing of 0.24 nm, characteristic of zerovalent
silver
Challenge testing
• Membrane - PVDF, UF membranes, average pore size - 0.04 µm
• Effective membrane area - 0.025 m2
• Flux - 30 or 50 L m-2 h-1
• Feed solution – Clean water with 5, 10 & 20 mg L-1 of silver
nanoparticles
• Parameters measured and/or compared – Clean water flux, TMP
• Change in TMP as a function of time, due t fouling of nanoparticles
Challenging compromised membranes with nanoparticles
• Physical compromise through punctures and cuts
SEM images
of the
punctures
made with a
100 µm
diameter
needle
• Chemical damage
o Exposure to hypochlorite solutions (Ct) of 2,500, 5,000, 10,000,
15,000 and 20,000 mg L-1.h
o Equivalent to a total exposure of 3.5, 6.9, 13.9, 20.8 and 27.8
months at 1mg/L concentration over multiple uses
Challenge testing contd.,
LRV and TMP change during the testing of intact UF membrane
Flux,
(L m2 h-1)
Nanoparticle
concentration,
(mg L-1 of Ag)
LRV
30
30
30
50
50
50
5
10
20
5
10
20
2.34±0.09
2.61±0.10
2.94±0.09
2.31±0.10
2.61±0.10
2.83±0.10
-0.3
0.5
0.5
0.0
0.5
0.3
• LRV ranging from 2.3 to 2.9 was demonstrated without any impact on the
operating flux
• Slightly high LRV could be established with high nanoparticle concentration
Challenge testing contd.,
• One puncture,
compromise ratio was
0.00003% and the LRV
decreased from 2.8 to 1.5
• Four successive holes, the
LRVs reduced to 1.1, 0.6,
0.5 and 0.3, respectively
• After three cuts, rejection
was 7.1 % and LRV <0.1
Challenge testing contd.,
• Realistic representation of the
impairment taking place in an
operational plant with routine
use of chemicals
• At 2500 and 5000 mg L-1.h, the
membrane resistance (Rm)
decreased to 19 and 38%, but
the rejection capacity was
almost unaffected
• Exposure to high concentrations
seem to affect both the
resistance and rejection
Summary MS2 vs silver nanoparticles
Criterion
Microbial indicators, bacteriophages
Analysis, lead
time
Long, 24 h to measure the integrity
breach
Citrate stabilised silver
nanoparticles
Small, using onsite measurement
techniques
Generation
labour intensive, needs PC2
Relatively low labour requirements
Plant
Preparation
High levels of disinfection of sample
points and preventative measures to
avoid contamination
Non-microbial, very little risk of
contamination by outside sources
Safety/hazards
Host bacteria require microbial safety
procedures
Minimal PPE
Background
interference
Potential chances of interference from
background virus and bacteria
Low Ag conc. In background
Measurement
limitations
PFU method may suffer from limitations
due to viral aggregation
No known limitations
Indicator
rigidity
Potential to deform under high pressure
and pass through the membrane
Unlikely to deform under high
pressure
4 Key Conclusions
• Demonstrated the suitability of new
citrate stabilised silver nanoparticles as
virus surrogates in terms of shape, size,
rigidity, charge and ease of detection
• Demonstrated close to 3 LRV of virus
removal for intact UF membranes
• Demonstrated the sensitivity of the
system to differentiate intact membrane
fibres from those with a low number of
physical breaches or chemical
degradation
• Demonstrated the potential for the
validation of UF membranes in recycled
water applications
Project is complete…..however..
Would like to work
• with a water utility to use these particles in
the field
• on the recovery of silver nanoparticles
Acknowledgements
