ULTRA HIGH EFFICIENCY PLEATED
DEPTH FILTER
F. Tepper, L. Kaledin, O. Vargas, T. Kaledin
Argonide Corporation
Sanford, FL

American Filtration Society Annual Meeting

March 22-24, 2010

Overview & Summary•

A dual pleated layer depth filter cartridge with electropositive properties(NanoCeram® or “NC”) is capable of greater than 6 LRV of virus and 7.5
LRV of E coli retention, at high flowrate and with high dirt holding
capacity.

•

An alternate cartridge includes powdered activated carbon, (NanoCeramPAC or “NC-PAC”) is capable of retaining both small particles andsoluble contaminants with high efficiency.

•

Both have wide application for purifying drinking water and in industrial,
food and drink and pharmaceutical manufacture.

•

Data are presented comparing the performance of these filters ascompared to a number of different depth filter media’s as well as
membranes.

•

Dual layer NC or NC-PAC is capable of better virus retention than mostof the depth media as well as a charged 0.1 micron membrane atflowrates that are ~ 25 times higher than the tightest of the depth media
or the membrane•

The retention of small particles or virus can deteriorate substantiallywhen in the presence of salt or at high alkalinity

About Argonide• Founded in 1994 to develop nano technology products;• Invented the NanoCeram® filter media (“NC”) in 2000, based on anano alumina fiber• Invented a combined chemical and biological filter – NanoCeram®PAC (“NC-PAC”)• Invented an air filter media capable of retaining high levels of virusElectron Microscopic Image
NanoCeram® Fibers
The active ingredient of the filter media is a nano alumina (AlOOH) fiber, only
2 nanometers in diameter.
The nano fibers are dispersed and adhere
to glass fibers and appear as a fuzz on the
microglass fiber.
The composite fiber is formed into a nonwoven media by wet processing. The water
filter’s pore size is ~ 2 microns.
Since the nano alumina fibers are dispersedand fixed in place, particles have easy
access to their charged surface.

Zeta Potential & Virus Removal
NanoCeram®
Wt % on Glass

Zeta potential, mV

MS2 Retention (%)

0

-35

8

5

-10

29

10

7

94

15

12

>99.999932

50>99.9999

Zeta potential becomes positive with increasing nano alumina and thiscauses a marked increase in retention of small particles such as virus(MS2).

T4 Phage crowded onto NC fiber composite

Courtesy E. Helmke, Alfred Wegener Institute, Germany

Sample prepared by immersion of media into concentrated T4 solution. Three phages
are encircled as examples, where the icosahedral head and tail are seen. The highdensity of electropositive charges results in attraction and adhesion of colloidal particles
such as virus.

PAC Filter• Powdered activated carbon (PAC) or any nanoparticle can beretained in the NanoCeram structure• The ~ 8 µ PAC particles are held in place by electroadhesive forces
due to nano alumina fibers• No adhesives are used
• There is minimal shedding of particles• The result is a carbon filter media (NC-PAC) with very high dynamic
sorption capacity for sub-micron particles as well as physiosorbablecontaminants

Free chlorine concentration, ppm

Chlorine Removal Comparison of PAC
2

Manuf-1, GAC 350 g/m
Manuf-2, PAC 250 g/m

2

2

Manuf-3, GAC 250 g/m

2

Manuf-4, GAC 250 g/m

2

1

Argonide 32%PAC/NC, 220 g/m

2

0

0

1000

2000

3000

4000

5000

6000

7000

2

Filtered volume (mL) through 1 layer of 3.7 cm of PAC (or GAC)
impregnated media at flowrate 16 ml/min and free chlorine input
concentration of 2 ppm

Chlorine attacks most membranes. NC-PAC is several hundred
times more efficient for retaining chlorine than other commerciallyavailable carbon media.

Filter Characteristics and Virus Retentionof NC and NC-PAC
Media

NC-PACOne layer

Thick,
mm
0.8

Basis
weight, g/m2
220

Challenge water
pH

TDSa g/L

MS2 removalb,c,
LRV

7
0
3.5
9.5
0
2.3
7
30
2.2
NC-PAC
0.8+0.8
220+22070>6.5
Two layers
=1.6
=440
8.5
0
>6.4
7
30
>6.6
8.5
30
>6.4
NC
0.8
220
7
0
3.0
One layer
9.5
0
2.3
7
30
2.2
NC
0.8+0.8
220+220
7.0
0
6.0
Two layers
=1.6
=440
8.5
0
5.5
7
30
4.8
8.5
30
4.1
Notes: a) Total Dissolve Solids (TDS) – sea salts; b) 5 ml aliquots were passed through 25 mmdisc at rate of 10 ml/min and collected into sterile vial; c) green color stands for high LRV (>5),
yellow color stands for moderate LRV from 2 to 5.

Filter Characteristics and Virus Retention
Competitive Depth MediaMedia

Pore size,µm

Thick,mmBasisweight, g/m2

Manufacturer A

1.1

5.0

1140

Manufacturer A

5.0

5.0

1140

Manufacturer B

0.6

2.6

1430

Manufacturer C

0.8

4.1

1571

Manufacturer C

1.3

4.1

1480

Manufacturer C

1.4

4.1

1470

Challenge water
pH

TDSa g/L

7
8.5
7
7
8.5
7
7
9.5
7
7
9.5
7
7
9.5
7
7
9.5
7
7

0
0
30
0
0
30
0
0
30
0
0
30
0
0
30
0
0
30
0

MS2
removalb,c,
LRV
>6.5
1.2
0.2
0.7
0.1
0.1
>6.6
5.2
0.3
6.8
4.8
2.3
5.1
0.1
0.7
1.0
0.2
1.2
0.3

Manufacturer D
0.1
0.15
60
charged membrane
Notes: a) Total Dissolve Solids (TDS) – sea salts; b) 5 ml aliquots were passed through 25 mm discs at rate of 10
ml/min and collected into sterile vials; c) green color stands for high LRV (>5), yellow color stands for moderate LRVfrom 2 to 5 and red color stands for very low LRV (<2).
.

Virus Retention of NC, NC-PAC andElectropositively Charged Membrane
Charged membrane, 0.1 micron pore size
NC-PAC, 1 layer
NC-PAC, 2 layers
NC, 1 layerNC, 2 layers
7

LRV, unitless

6
5
4
3
2
1
0
0

10

20

30

40

50

Filtered volume through 25 mm discs, mL

60

Filtration of Sub-Micron Organic Particles
22

Filtrate turbidity (FTU)

20
18
16
14
12

0.025 micron pore size membrane
0.22 micron pore size membrane
0.45 micron pore size membrane
NC
NC-PAC
Starting FTU

10
8
6
4
2
0
25

50

75

100

125

150

Filtered volume (mL) through 47mm diameter disc
Data Courtesy of Heather Mowers, Ahlstrom Filtration

Membranes and NC media are challenged with humic acid, a particle smaller
than a virus. Note that both NC and NC-PAC had far better retention than even a
0.025 µ membrane (which clogged almost immediately).

Virus retention by mixed cellulose ester
membrane filters
Mean pore size, mm

Flow velocitya, cm/min

MS2 removal, %

0.025
0.1
0.22
0.45
1.2

2b
10
10
10
10

73± 3c1 ± 110±64±6
1±7Notes: a) Fifteen mL aliquotes of MS2 solution at input concentration of 3.5*106 PFU/mL
were passed through 25 mm diameter membrane at flow rate 40 mL/min through ~4 cm2
surface area (corresponds to 10 mL/min) of 1.2 mm, 0.45 mm, 0.22 mm and 0.10 mmmembranes; b) Pressure drop for the 0.025 µm membrane was higher than 40 psi at theabove flow rate therefore we were using ~5 times lower flow rate through the 0.025 mm
membrane, i.e., 8 mL/min (or flow velocity ~2 cm/min); c) red color stands for very low
MS2 retention (<1 LRV or <90%).

Is there a flaw in Absolute membrane ratings?
•

The previous slide suggests that there is major slippage of biologicalparticles through membranes that have smaller pores than the size of theparticles•

This was observed by Ch. Wick and P. E. McCubbin1. MS2 has a reported
MW of 2 million Daltons. Yet they found that MS2 virus passed throughfilters rated at 300 K Daltons•

The phenomena of “grow-through” of bacteria is known to occur throughmedia rated smaller than their nominal size•

We suggest that biological particles are comprised of viscous fluid
encapsulated by membranes, so that they are not rigid particles but are
sufficiently plastic to penetrate•

Adsorption of such particles by electroadhesion rather than by mechanicalfiltration, could circumvent this flaw

1. Charles Wick and P. E. McCubbin, U S Soldier and Biological Command, Filtration
Characteristics of MS2 Using Various Molecular Weight Filters – 1999- ECBC Rept TR-054

Virus Retention Conclusions• NC-PAC in two layers has equivalent or better virus retention thanother depth filters including the smallest pore size ones
• NC has lesser virus retention than NC-PAC, but it is still muchgreater than other depth media with the exception of the finest grade• Both NC and NC-PAC have better retention than the 0.1 µ pore size
charged membrane, even at neutral pH.
• The virus retention of the competitive depth filters falls substantiallyor is nil when in the presence of highly alkaline or conductive (salty)
matrixes, while NC and NC-PAC are minimally affected by salt or
alkalinity.

Bacteria Retention by NC and NC-PAC MediaMedia

Thick,mmBasisweight,g/m2

Challenge water

E. coliremovalb,cLRV

B. diminuta
removalb,c
LRV

TDSa
g/L
NC-PAC
0.8
220
7
0
>6.0
>8.7
One layer
9.5
0
>6.3
>6.2
7
30
>6.2
>5.5
NC-PAC
0.8+0.8
220+220
7
0
>7.5
8.0
Two layers
=1.6
=440
9.5
0
>6.5
>6.2
7
30
>6.5
>5.9
8.5
30
>6.5
NC
0.8
220
7
0
>6.0
4.5
One layer
9.5
0
>4.5
4.7
7
30
4.2
5.2
NC
0.8+0.8
220+220
7.0
0
>7.5
>7.6
Two layers
=1.6
=440
9.5
0
6.3
>6.2
7
30
>7.0
>5.9
8.5
30
>7.0
Notes: a) Total Dissolve Solids (TDS) – sea salts; b) 5 ml aliquots were passed through 25 mmdiscs at rate of 10 ml/min and collected into sterile vials; c) green color stands for high LRV (>5),
yellow color stands for moderate LRV from 2 to 5.
pHBacteria Retention byCompetitive Depth Media
Media

Pore
size,
µm

Thick,mmBasisweight,g/m2

Manufacturer A

5.0

5.0

1140

Manufacturer B

0.6

2.6

1430

Manufacturer C

0.8

4.1

1770

Challengewater
pH TDSa
g/L
7
0
8.5
0
7
30
8.5
30
7
0
9.5
0
7
30
7
0
9.5
0
7
30

E. coliremovalb,cLRV

B.
diminuta
removalb,c
LRV

1.1
1.2
1.5
1.8
8.0
>6.5
>5.5
>7.6
>6.5
>5.5

Notes: a) Total Dissolve Solids (TDS) – sea salts; b) 5 ml aliquots were passed through 25 mmdiscs at rate of 10 ml/min and collected into sterile vials; c) green color stands for high LRV (>5),
red color stands for very low LRV 2.

Bacteria Retention of Depth Media Conclusions• Better than 6 LRV of E coli and >5.9 LRV of B diminuta wereretained by two layers of NC and NC-PAC whether in alkaline or in
the presence of salt
• E coli retention by Manufacturer A’s 5 µm media was poor
• The loss of retention at high pH or with salt was not significant in thecase of the competitive depth media with particles much larger thana virus. The presumption is that these larger particles are retained
primarily by mechanical filtration, rather than being dependent onelectroadhesion.

Flowrate of Various Depth Media

Pressure drop, psi

12NC, 1 layerNC, 2 layers
NC-PAC, 1 layer
NC-PAC, 2 layers
Manuf. A, 1.1 micron pore size
Manuf. A, 5.0 micron pore size
Manuf. B, 0.6 micron pore size
Manuf. C, 0.8 micron pore size
charged membrane, 0.1 micron pore size

Manuf. B & C & A

NC-PAC, 1 layer

10
NC, 2 layers

8

NC-PAC, 2 layers

Manuf. A

membrane, 0.1 micronNC, 1 layer

6
4
2
0
0

50

100

150

200

250

300

350

400

Flow velocity, LPM/m 2

450

500

550

Retention and Dirt Holding Capacity of Test Dust
Media

Pore
size,
µm

Numberof layers

Thick,
mm

Total
Flow
Dirt
Weight velocity (inholdingcm/s) atcapacitya,b
g/m2
mg/cm2∆P=3 psi
2200.226c
58
d
0.111
220
0.286c
57
d
0.114
1280
0.014
49

NC

2.0

1

0.8

NC-PAC

2.0

1

0.8

Manuf. A media

1.1

1

3.8

Manuf. A media

5.0

1

5.0

1140

0.230

119

360

Manuf. B media

0.6

1

2.6

1430

0.006

22

>25,000

Manuf. C media

0.8

1

4.1

1770

0.007

13

1000

Manuf. C media

1.4

1

4.1

1470

0.015

27

270

β ratio>25,000>25,000>25,000

Manuf. D
0.1
1
0.14
60
0.010
34
>25,000
Charged membrane
Notes: a) A2 fine dust produced by PTI, Inc.; b) to terminal pressure of 30 psi at input
concentration of 250 NTU (0.4 g/L); c) single layer; d) double layer; e) red color stands for
low flow velocity and β value

Flowrate Remarks• With the exception of Manufacturer A’s coarsest media (~5 µm),
both NanoCeram and NC-PAC ( both 2 µm pore size) in two layers
have a higher flowrate than any of the other media that were tested.

• A single layer of NC or PAC has a higher flowrate than any of thedepth media but one (Manuf. A- 5 µm).

• At DP=3 psi, a single layer of NC or NC-PAC has a flux
approximately 130 LPM/m2. This is 25 times as great as the 0.1 µm
membrane as well as the smallest pore size media tested, and yetboth NC’s have much greater virus clearanceTurbidity Retention of Media’s

Output turbidity, NTU

1
NC, 1 layer
NC-PAC, 1 layer
Manuf. A, 1.1 micron pore size
Manuf. A, 5.0 micron pore size
Manuf. B, 0.6 micron pore size
Manuf. C, 0.8 micron pore size
Manuf. C, 1.4 micron pore size

0.1

0.01

0.001
0

100

200

300

400

500

Filtered volume through 25 mm disc, mL

600

700

Dirt Holding Capacity Conclusions• With the exception of Manufacturer A’s 5 micron depth filter, NC and
NC-PAC retain more test dust than any of the other media’s tested.
• Of all of the depth media, only NC or NC-PAC is thin enough to bepleated – Both NC and NC-PAC, when in a pleated cartridge, would
have higher dirt holding capacity than any of the competitive planar
media tested including Manufacturer A’s 5 micron media• Several grades of depth media show early leakage of test dust
therefore substantially reducing their β value as compared to NC
and NC-PAC

Bio testing of NC and NC-PAC cartridges
Cyst
Cartridge Cartridge Cartridge Number of Flowrate, MS2, Bacteria removal
Height, Diameter, layers
GPM removal,
removal,LRVa,e Bacteria
cm
cm
LRV
LRVa,f
PAC2.5x5
12
7
1
2
3.4
KTb
7.1
>3.7
b
P2.5x10
24.5
7
1
4
3.1
KT
>7.1
>3.7
DP2.5x10c

24.5

7

2

4

>6.0

E. coli

7.4

NDd

PAC2.5x20

50

7

1

8

>4.5

E. coli

7.3>3.7

P4.5x10

24.5

11

1

8

>4.5

E. coli

7.5>3.7

P4.5x20

50

11

1

22

>4.3

KTb

>5.0

>3.7

Notes: a) Logarithm retention value; b) Raoutella terrigena (deposited as Klebsiellaterrigena); c) double pleated; d) ND – not done; e) green color stands for high LRV (>5),
yellow color stands for moderate LRV from 2 to 5 and red color stands for very low LRV(<2); f) WQA tested single layer NC-PAC for Cryptosporidium (cysts) using latex spheresurrogates. The cartridges exceeded the drinking water requirements of >99.95% (>3.3
LRV) retention according to NSF/ANSI 53 International Standard.
.

Third party testing of cartridges
Initial Retention Efficiency per ASTM F795-88 using Black Iron Oxide Contaminanta at
High Alkalinity (pH 9.5) and Elevated Temperature (65°C)
Cartridgeb
Argonide
P2.5x10c
Cartridge

Upstream
particle countDownstream
particle count

Manuf. E
P2.5x10c
Cartridge

0.1-0.25
283849Particle size ranged, microns
0.25-0.5 0.5-0.6 0.6-0.8 0.8-1.0
16873646095 19008
8710

>1
13959

67

21

15

<1

<1

99.99

99.97

>99.995 >99.99>99.993282356

85009

38698

25328

27382

24671

3484

2479

896

114

91.26

95.90

93.59

96.46

99.58

Port

Net
99.98
Efficiency, %Upstream
349554
particle countDownstream
particle count123199Net
64.76
Efficiency, %<1

Data Courtesy of DCS Control
Notes: a) Test was done by IBR Laboratories, Grass Lake, MI; b) Flow Rate – 4 USGPM; c)c/w double 222 o-rings & alignment fins; d) Upstream/Downstream numbers appearing in the
Table, are the number of test particles for a size range counted by the laser device MC100S
s/n M1029.

Conclusions about Cartridge Testing• With NC and NC-PAC, the results obtained to date show excellent
scalability from discs to cartridges• Bacteria retention was higher than 5 LRV with a single pleated layer
and higher than 7.4 LRV with double layer (NC)
• WQA tested single layer NC-PAC pleated cartridges for
Cryptosporidium (cysts) using latex sphere surrogates. They
exceeded the drinking water requirements of >99.95% retention forcysts• Testing by IBR for ultrafine particles shows very high retentivity by
NC over the whole particle size range, achieving 99.98% retention ofparticles between 0.1 and 0.25 microns, at pH 9.5 and 65° C!

Comparable Endotoxin Removal
Endotoxin removal by NanoCeram filters via the LAL method
Challenge
watersFilterthickness, mm

Filtration
rate,
ml/cm2/min

Water +
endotoxin

1.5 =~2 layers
1.5 =~2 layers
1.5 =~2 layers
1.5 =~2 layers

10
10
2
2

Filteredvolume persq. cm,ml/cm2
0.8
0.8
1.4
1.4

Influent
Endotoxin
concentration
EU/ml
10
235
4.8•105
4.2•105

Effluent
Endotoxin
concentration
EU/ml
0.12
<0.12
9.7•103<0.6

5% Dextrose inEndotoxin freewater
1% Liposyna II
1.5 =~2 layers
2
1.4
4.2•105
9.7•103
in Endotoxin
free water
Notes: a) Liposyn II is an intravenous fat emulsion. A 10% composition contains: 5-wt%
safflower, 5-wt% soybean oil, up to 1.4–wt% egg phosphatides (as emulsifier) and 2.5-wt%
glycerin b) green color stands for high endotoxin retention (>99%), yellow color stands

Retention
factorb,%
98.8>99.9598.0>99.9999

97.7

for moderate retention from 90% to 99%.

Endotoxins, which are a serious particulate contaminant inpharmaceuticals, can be as small as a virus and are difficult to filter.
NC has a high endotoxin removal efficiency

Safety & Environmental•

There are significant concerns about the impact of nanomaterials on health,safety and on the environment.

•

Nanoalumina fibers also known as boehmite (AlOOH) fibrilles, have beenused in antacids such as Maalox for many years before being replaced by
Al(OH)3. The latter is lower in cost and dissolves more rapidly in stomach
acids.

•

Boehmite nanofibers have also been used extensively in vaccines. In thatapplication they are called adjuvants. They have been FDA approved for 63
years as a primary component of baby shots and flu vaccines. More than 2billion doses have been used in humans and countless more in veterinary
vaccines.

•

Numerous studies of occupational exposures of all aluminas, including
boehmite, used in industry are essentially inert in the lungs*•

Aluminum in all forms, shed or dissolved from NC filters has been shown tobe <20 ppb (via ICP/MS).
(*Dinman, Graduate School of Public Health, Univ Pittsburgh, 1990, in Alumina Chemicals Science andTechnology Handbook, Amer Ceramic Soc)

Emulsified Oil Removal by NC•Low levels of oil or oil emulsions are often an undesirable contaminant•Current technology is not effective for polishing low levels of emulsified
oil after oil skimming and coalescing systems.
•NanoCeram or NanoCeram-PAC can retain emulsified oil

Turbidity of oil in water, NTU

60

40

Oil in water droplets turbidity
Removal of oil in water droplets by NanoCeram media,
1 layer
20

200 mg oil/1g media or 50 g oil/m2

0
0

100

200

300

Filtered volume through 25 mm diameter disc, mL

400

Dual Layer NC and PAC Cartridges

Dual pleated layer 2.5 and 5” diameter cartridges fit instandard housingsLenticular Filter Replacement

The dual pleated layer NC (or NC-PAC) cartridge on the left
is a drop in replacement for the lenticular filter (right)

NC and NC-PAC as Alternates to Membranes•••

There is a large and growing market for fine particle depth filters aswell as for MF/UF membranes
Approximately 20% of all membranes sold are for filtering particulate
MF/UF membranes are used to produce pure and ultrapure water in a
number of industries: Microelectronics
 Food & Drink Pharmaceutical manufacture Automotive manufacture Protecting RO membranes•

NanoCeram filters have substantial advantages over charged depth
filters as well as MF/UF membranes
 Less expensive than membrane cartridges or charged membrane Flux tens to hundreds of times greater than membranes
 Higher filtration efficiency
 Greater dirt holding capacity then most depth media and all
membranes tested
 No water waste as compared to membranes that might be used intangential flow

Removing Colloidal Iron and Copper
Two Case Studies•

Colloidal iron can pass through a 25 nm pore size membrane and would
not be intercepted by any of the competitive depth media•

Toyota has a 5 million gallon chilled water system in their Kentucky
plant, with over 20 Miles of 4” pipe and larger + seasonal flow and deadlegs•

Significant corrosion was observed in the piping system, causing grave
concern and cost in the event of replacement•

The corrosion is caused by iron bacteria that use colloidal iron as a foodsource•NC removed all measurable colloidal iron, manganese and iron bacteriain Toyota’s pilot test•

Another user found that NC double pleated cartridges, used in a chiller,
retained both iron and copper (probably as oxides or hydroxides), while
Manufacturer A’s lenticular was transparent to both these metals.

Features and Benefits of NanoCeram• NanoCeram® are cost effective filters for removal of sub-micronparticles from water• NC-PAC has somewhat better particulate retention than NC and at
the same time has a high dynamic efficiency for retaining chlorine• NC and NC-PAC’s performance exceeds depth filters and MF/UF
membranes in virtually all respects• A single layer NC or NC-PAC filter covers the gamut of particle size
ranges from micron to a few nanometers and does so at moderate
to high flowrate and dirt holding capacity.
• And it can be used as an prefilter to protect RO in fresh water andseawaterWe create and make great things

THANK YOU
Fred Tepper, fred@argonide.com (407-322-2500 x102)
www.argonide.com