AFM® Activated Filter Media

Independent performance test results, January 2014*

IntroductionThe following report summarises the performance test results of Dryden Aqua AFM®, quartz sand and other glass filter media commonly on the market. All work was conducted by IFTS (Institut de la Filtra-tion et des Techniques Séparatives www.ifts-sls.com) in France, recognised as one of the leading inde-pendent accredited laboratories on water filtration media worldwide.

AFM® is a highly engineered filtration media manufactured from green container glass as a raw material.

The following report relates only to the mechanical filtration performance. The tests were conducted on clean media. It is known that sand and non-activated crushed glass media will become a biofilter over a period of a few months. The bacteria adversely affect mechanical filtration performance and promote wormhole channelling. Bio fouling and there for channelling does not happen with AFM®.

Filter media testedProducts tested were as follows:

• AFM® Dryden Aqua, Scotland

• QuartzSandfromtheLeightonBuzzarddeposit,England

• Garofiltrecrushedglassmedia,France

• EGFMbyDMScrushedglassmediamanufactu-red by implosion, England

• Biomacrushedglassmedia,Spain

• Vitrospheresphericalglassballs,Germany

• Astralcrushedglassmedia,Spain

Review of data Three factors are important in media bed filtration:

1. Mechanical filtration

2. Adsorption reactions

3. Performance with coagulation and flocculation

*Tests conducted by IFTS: www.ifts-sls.com

Test 1: Particle size removal efficiency AFM® will remove 80 % of all particles in the water down to 4.5 microns. The best a very high quality sand can achieve is 8 microns. The results were collected from filters operated at 20 m/hr filtration velocity with no flocculation. Therefore the results are a direct comparison between the different filtration media.

The chemistry of the glass, the particle shape and especially the activation process give AFM® the important properties to clearly outperform sand and glass sand filter media .The large surface has a strong negative charge to adsorb organics and small particles. The surface also has metal oxide catalysts which produce free radicals and thus a high redox potential. Therefore AFM® is self-disinfecting. AFM® prevents bacteria from settling to make it a unique, bio-resistant filter material.

Graph 1: Smallest particles removed at 80 % performance at 20 m/hr velocity and no flocculation

Source: IFTS test data, France, 2014

Smal

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AFM®Sand16/30 Garo EGFM Astral Bioma

VitroSphere

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Sand 16/30

Garo

EGFM

Astral

Bioma

Vitro Sphere

AFM® Sand 16/30

Garo Astral Bioma EGFM Vitro- sphere

Efficiency at 5 microns Removals %

Initial % 76.78 55.30 77.51 79.91 39.02 76.65 49.00

Final % 82.40 74.85 63.97 39.04 3.70 53.70 0.00

Average % 81.30 72.97 65.61 49.35 7.45 58.03 0.05

Differential pressure Initial mbar 155.00 149.00 88.00 124.00 111.00 222.00 121.00

Final mbar 934.00 891.00 808.00 550.00 511.00 934.00 123.00

Injected mass Grams 109.00 133.00 266.00 209.00 400.00 109.00 201.00

Summary of filter media performance at 5 microns, water flow 20 m/hr

Source: IFTS test data, France, 2014

CommentsAFM® and sand proved to be the most efficient as none of the other media could achieve a high end of test pressure due to retained solids break-through. AFM® was also the best with respect to average and final filtration performance at 5 microns, at a filtration velocity of 20 m/hr. The tests were conducted in un-clarified water.

Test 2: Differential pressure vs Injected mass ISO CTD particles were injected into the process water to test the capacity of the media to remove particles from the water. As the particles are removed from suspension, pressure should gradually build up in the filter bed until it eventually blocks. Only the AFM® and sand filter beds blocked, all other media allowed particles to break through the filter bed and return to the process water.

Ability to retain particles is very important in any filtration system. In drinking water and swimming pool systems, where crypto-sporidiosis presents a significant disease risk, filters must be stable and able to retain parasite’s. Sand and AFM® were the only two products to offer a stable filtration barrier.

Source: IFTS test data, France, 2014

Test 3: Backwash efficiency The quantity of material released over time was measured for each of the various media. The graphical data for backwash efficiency confirms that both sand and AFM® achieved 97 % backwash efficiency.TheclosestglassmediawasGarofiltreat93%followedbyAstralat92%andEGFMat88%.

What goes into a filter must come back out, if this does not happen the retained organic matter will be subjected to bacterial metabolism and even-tually the filter media will bio-coagulate due to an accumulation of alginates secreted by bacteria and mineralised biofilm layer.

The backwash profiles shown in graph 5 show the quantity of solids discharged from a filter bed during a backwash.

The backwash profile for AFM® follows a reproduci-ble and predictable sine curve. The sand presents an erratic and non-predictable backwash profile. Also when the area below the curve is measured it confirms that 30 % more solids have been eluted from the AFM® filter in comparison to the sand filter operating under identical conditions.

Experience demonstrates that AFM® backwash efficiency is sustainable whereas bioaccumulation leads to a deterioration of performance in other media. This affects both performance and running cost, as progressively more water is required even for an incomplete backwash of other media.

Source: IFTS test data, France, 2014

Graph 4: Back-wash profile for sand and AFM®

30 60 90 120 150 180 210 240 270 300 360 420

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Backwash time [s]

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Source: Lyonnais des Eaux

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Injected mass grams (g)

Graph 3: differential pressure vs injected mass

AFM®

Sand 16/30

Astral

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EGFM

Vitrosphere

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Time in minutes for back-wash

Graph 4: back-wash efficiency

AFM®

Sand 16/30

Astral

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Bioma

EGFM

Vitrosphere

Graph 2: Differential pressure vs injected mass

Graph 3: Back-wash efficiency

Result discussion

www.drydenaqua.com © D

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Key points• AFM® performed the best in tests, twice as well as the closest crushed glass product and 40 % better

than the highest quality sand (see graph 1 & table page 2)

• Sandperformedbetterthanallotherglassmedia(seegraph1&tablepage2)

• Allcrushedglassproductsfailedtheinjectedmasstestleadingtodischargeofunfilteredmaterialbackto the process water with no effective barrier against e.g. cryptosporidium parasites, bacteria or organic matter (see graph 2)

• Noneoftheglassproductstestedbackwashedwithin6minutes,thebeststillretained8%ofsolids,andthe worst retained 20 %. This translates to a significantly higher water requirement for backwashing and a higher chlorine demand resulting from retained organic matter (see graph 3)

Conclusion The test results demonstrate the advantages of AFM® over all other filter media tested. AFM® clearly outperformed high quality quartz sand and any other glass filter media.

Chlorine oxidation demand in chlorinated systems and the formation of disinfection by-products relates directly to filtration and backwash efficiency. The data presented confirms a considerable performance advantage of using AFM® over sand and any other glass filter media.

Additional information: What is AFM® activation? AFM® activation is a patent protected 3-stage process during which the surface structure of the glass is changedatamolecularlevel.Glassisanaluminosilicate,theactivationprocessusestheexistingpropertiesof the glass which is why Dryden Aqua only use green container glass. In addition the production process enhances the glass’ properties by:

1. Increasing its catalytic properties

2. Controlling its surface charge density

3. Increasing its surface area

4. Controlling the selective molecular sieve structure of the surface

Electrochemical adsorption, moleculare sieve adsorption and performance with coagulation and flocculation chemicals will be covered in additional reports in the near future.

Picture 1: AFM® surface (500 nm) Picture 2: AFM® surface (2.0 µm)