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Reduction of Broad Spectrum NOM Contamination to Minimize Fouling of Membranes Using Electroadsorptive Depth Filter Media
Rod Komlenic Product Manager, Disruptor Filtration TechnologyAhlstrom Filtration LLCrod.komlenic@ahlstrom.com
IWA NOM ConferenceCosta Mesa CaliforniaJuly 26-29, 2011
Presentation outline
• Introduction to electroadsorptive filtration technology
• Reduce or remove a variety of NOM
• Significance of Transparent Exopolymer Particulate (TEP)
• Impact of reduction of NOM to membrane biofouling
© 2011 Ahlstrom Corporation Page 2
Electroadsorptive water filtration technology
• Nanofibers of pseudoboehmite AlO(OH)
• 2 nm X 250 nm in size
• Grafted to microglass
© 2011 Ahlstrom Corporation
R.Ristau, IMS, UCONN
• Grafted to microglass carrier
• Positive electrokinetic potential
Media structure
• Average pore size of 2 microns • ~400 such pore layers in 0.8 mm depth• Torturous path, depth filter
© 2011 Ahlstrom Corporation
Photo courtesy of R. Ristau, IMS, Univ. of Conn
Charge field coverage
© 2011 Ahlstrom Corporation
• Charge potential is generated by the alumina fibers• Charge field radiates to a maximum distance of 1 um
Image: Dr. J Brant Univ of WY
Other removal mechanisms
• Ion Exchange - At low pH (below about 5 pH) the protons of the OH group are tightly bound. As the pH increases to > 6 the proton bonding is weakened, allowing proton exchange from some positively charged colloids.
© 2011 Ahlstrom Corporation
• pH change near nanofiber up to +2 possibly causing coagulation and flocculation
MS2 retention comparison
Media Thickness mm
Basis Wt g/m 2
Challenge Water MS2 Removal, %
pH TDS g/L
MS2, PFU/ml
0-10 ml
60-70 ml
130-140 ml
Disruptor®
0.8 200 7.2 0 3·105 99 98 94 9.2 0 6·105 90 90 7.2 30 5·105 97 97
© 2011 Ahlstrom Corporation
7.2 30 5·10 97 97 9.2 30 4·105 96 88
3m Virasorb®
0.8 210 7.2 0 6·105 99 92 62 9.2 0 3·105 60 13 7.2 30 5·105 4 6 9.2 30 4·105 0 0
Data courtesy Argonide Corp
• Typical MS2 reduction for 1 layer is now > 4 LRV
Trace hydrocarbon reduction
© 2011 Ahlstrom Corporation
Capability to remove trace and emulsified hydrocarbons with a capacity of up to 50 g/m2 such as BTEX, etc.
Data courtesy Argonide Corp
TOC reduction using Tempe Town Lake water
© 2011 Ahlstrom Corporation Page 11
Data: Arizona State University
TOC reduction of water with Suwannee River fulvic acid
© 2011 Ahlstrom Corporation Page 12
Data: Arizona State University
Humic acid reduction
Average Turbidity & Flow Rate to Filter Set Volumes of 20 FTU Humic Acid at a Constant Pressure Through a 38mm (1133mm 2) Circle of 799-81
6
8
10
12
Filt
rate
Tur
bidi
ty (
FT
U)
250
300
350
400
450
Flo
w (
mL/
min
)
FTU
mL/min
© 2011 Ahlstrom Corporation
0
2
4
6
100 200 300 400 500 600 700 800 900 1000 1100 1200 1300 1400 1500 1600 1700 1800 1900 2000
Set Volumes of 20FTU humic acid solution (mL)
Filt
rate
Tur
bidi
ty (
FT
U)
0
50
100
150
200
Flo
w (
mL/
min
)
mL/min
Challenge concentration = 20 FTUData: Heather Mowers, Ahlstrom Filtration LLC
TEP and chlorophyll reduction
50
75
100
% R
educ
tion
% Reduction of TEP and Chlorophyll
% TEP
© 2011 Ahlstrom Corporation Page 14
Testing by Dr. Thomas Berman, Kinneret Limnological Laboratory
0
25
50
RJ WW LKW
% R
educ
tion
% TEP
% CHl
SEM of Disruptor ® - New and fouledLeft: Surface of a new sample of Disruptor®
Right: Surface after being fouled with polysaccharides. Testing done using unfiltered North Sea water.
© 2011 Ahlstrom Corporation
Images courtesy of Ibrahim El-Azizi, and Robert J. G. Edyvean, University of Sheffield, UK.
Features of PAC media
• Uses Powdered Activated Carbon (PAC) particles where 90% pass through a 625 mesh screen.
• PAC is retained by the electroadsorptive charge field during the wet laid paper making process.
• Retains smaller particles of carbon, than is possible by mechanical entrapment
© 2011 Ahlstrom Corporation
mechanical entrapment
• Carbon has high surface area to mass ratio producing extremely rapid reaction kinetics
• Increased capacity for removing certain types of NOM
Membrane biofoulants
NOM biofilm Constituents:• Virus• Bacteria
© 2011 Ahlstrom Corporation January 2011
Ultrapure Water April 2010 Jane Kucera, Nalco.
• Cell debris• Organic acids• Extracellular materials
TEP and membrane fouling
© 2011 Ahlstrom Corporation Page 20
Images courtesy Tom Berman and Uta Passow
TEP shown as blue, bacteria shown as brown. TEP may provide the primary conditions for biofouling . Bacteria growth contribute to biofilm. Other colloids (light blue).
Nanoparticle free backwash
Removed negatively charged
nanoparticles (dp = 57 nm) from MF
filtrate
Deposition throughout membrane
© 2011 Ahlstrom Corporation Page 21
Deposition throughout membrane
using MF filtrate (top)
“Polished” filtrate showed
qualitatively better removal of
nanoparticles (bottom)
Data: Dr. Jonathan Brant, University of Wyoming
Impact on membrane performance
• Disruptor® used to pretreat MF
feed containing nanoparticles
• Negatively charged (ζ = -30 mV)
TiO2 nanoparticles
• Pretreatment improved 150
200
250
300
Flu
x R
ate
(m3 /
m2
day)
© 2011 Ahlstrom Corporation Page 22
• Pretreatment improved
membrane performance
• Rapid flux decline for untreated
feedwater (50% flux decline)
• No observable flux decline for
pretreated water
0
50
100
150
0 50 100 150 200 250 300
Flu
x R
ate
(m
Time (sec)
[TiO2]feed = 0.5 mg/L; pH = 8.0; n = 3I = 10 mM NaCl
Data: Dr. Jonathan Brant, University of Wyoming
Preliminary results
• Pilot trials have been ongoing for approximately one month,
• Membranes operated using same conditions, with regards to
filtration rate, backwash frequency and duration
• Laser turbidimeters installed to assess/compare MF filtrate
quality
© 2011 Ahlstrom Corporation Page 23
quality
• Backwashing with “polished” MF filtrate has improved overall
membrane performance
• Polished filtrate results in less flux decline over time (Δ ~ 15%)
• Terminal TMP (ΔP = 22 psig) not yet reached for either MF
membrane
Data: Dr. Jonathan Brant, University of Wyoming
Improved TDS rejection RO prefiltration trial
% R
ejec
tion
© 2011 Ahlstrom Corporation
Sample Intervals
% R
ejec
tion
• Higher TDS rejection levels with the Disruptor® prefilters
• TDS rejection more consistent with the Disruptor®
• TDS rejection from the other trains were lower and erratic
RO performance - % recovery
© 2011 Ahlstrom Corporation
• The percent recovery = percentage of total influent
produced as permeate
• 0.2u and the 1u prefilters had lower initial permeate
recovery and declined significantly over the study period.
Days 1-23
Ca, Mg, Na, SiO₂₂₂₂ rejection by RO systems
% R
ejec
tion
© 2011 Ahlstrom Corporation
% R
ejec
tion
• RO membranes with Disruptor® prefilters had higher rejection
rates for Magnesium, Sodium, and Silica
• Calcium rejection levels similar-slightly higher with Disruptor®
Micro contaminant removal
• Microcontaminants now being detected in many waste water and in some potable water sources.
• The dangers these contaminants present to humans and the environment are not well understood
• Reduction of removal of these compounds is of interest to
© 2011 Ahlstrom Corporation
• Reduction of removal of these compounds is of interest to many health authorities and agencies
• Testing by the University of California Irvine has shown Disruptor® to be effective in removing traces of Penicillin G, Bisphenol A (BPA) an endocrine inhibitor and the antibiotic Flumequinean
Page 28
Penicillin G removal
© 2011 Ahlstrom Corporation
Penicillin G studied at 2 mg.l with total removal from 13 liters. At typical concentration of 2 micrograms per liter, a square foot of Disruptor® PAC could process > 900,000 l of water, free of other contaminants.
Bisphenol A (BPA) removal
© 2011 Ahlstrom Corporation
BPA is an estrogenic chemical used in the manufacture of polycarbonate resins. Complete removed from 3 l of water at 10 mg/L. At 2 micrograms per l, 1 ft 2 of media could process > 1 million liters, free of other contaminants.
Flumequine removal
© 2011 Ahlstrom Corporation
Flumequine, a chemotheraputic antibiotic was completely removed from 3 l having a concentration of 10 mg/L. At more typical concentration of 2 micrograms/l, a square foot of media could process > 1 million l.
PCB removal
© 2011 Ahlstrom Corporation Page 32
Polychlorinated biphenyls (PCBs) are man made organic chemicals but are included for general information
Value proposition
1
5
1
00
Pre
ssur
e in
Bar
Virus BacteriaAqueous Salts
Endotoxin
Nanofiltration
Reverse Osmosis
Disruptor®
Disruptor®
1
5
1
00
Retention Efficiency in Microns
0.0001 0.001 0.01 0.1 1.0
Pre
ssur
e in
Bar
Ultrafiltration
Disruptor®
MicrofiltrationDisruptor®
Conclusions
Ahlstrom Disruptor® is a new category of filter media removing contaminants through electroadhesion and ion exchange, not mechanical filtration.
Efficiently retains a wide range of NOM - cell debris, endotoxins, pathogens and organic acids.
High flow rate, low pressure drop and high capacity give
© 2011 Ahlstrom Corporation
High flow rate, low pressure drop and high capacity give good value through filtration efficiency and energy savings.
Technology offers new opportunities for potable and waste water treatment.
Commercially available since 2006.
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