The following is a page providing the current list of certification documents for AFM® which has been tested by IFTS  the leading independent accredited laboratory in Europe specialising in the the testing of filter media for the Water Industry.

Mr. Vincent Edery the Director of IFTS commenting on Dryden Aqua’s AFM® said: ” The visit to Dryden Aqua is exactly what we hope to find in a company that invests so heavily in R&D. They opened a new 40,000 tonne processing facility around a month ago and already the Dryden Aqua team have a mature and stable product which is out-performing sand and other all glass media tested. I have been struck by the depth of scientific knowledge within the firm and their mission to push the boundaries to discover the potential of Activated Glass as a molecular sieve for water filtration.

ebae blue vibes

ISO9001-2008 certification document

BSEN12902 by WRC-NSF

DWI Reg 31 document


Entec Risk Analysis

IFTS report on AFM®,  Environmental Technology Verification

ISO 140001-2004 in progress

NSF 50 in progress

NSF61 International certification for drinking water by WQA

AFM patent pending.  No 1323094.1

Circular economy award for sustainability VIBES

Hydro Nation award by VIBES for excellence in water treatment

Dryden Aqua is 1 of 12 companies representing the UK in Lyon 2014 for the European Environmental Awards


It should be noted that certification is not verification that a product is actually fit for purpose.  Most certifications for drinking water applications such as NSF61 are based only on a heavy metal leaching test. The test only confirms that the product will do no harm, not that it is a good filter media.  For this reason Dryden Aqua as part of the Scottish Hydro Nation government committee has initiated ETV and Environmental Technology Verification scheme to properly determine the performance of different types of filter media. The initial tests have been conducted with IFTS which confirm the superiority of AFM® over all other types of filter media tested.

It should be noted that the sand used was Leighton Buzzard sand from England, which is considered to be the best sand in Europe. The results from the sand were much better than the crushed glass tested, and almost as good as AFM®.  However sand deteriorates with age due to biofouling, whereas AFM® actually improves with age due to a continued development of the activated surface chemistry.

ISO 9001 2008 Logo IFTS logo

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

  AFM®Sand  16/30GaroAstralBiomaEGFMVitrosphere

Efficiency at 5 microns.percentahe removals %

Initial %








Final %








Average %








Differential pressure

initial mbar








final mbar








injected mass










AFM® and sand are the best since all the other media cannot achieve a high end of test pressure due to retained solids break-through. AFM® was also the best with regards to the average and final filtration performance at 5 microns, flow was 20 m/hr. Tests conducted in un-clarified water

Particle Size Performance

afm grade0 1 performance

The graph below confirms that AFM grade 0 is removing all particles from the water down to 4 microns at a water flow of 20m/hr.  More than 97% of all 1 micron particles were also removed, at a water flow of 5m/hr this will be increased to effectively 100%.  Grade 0 AFM is a fine filter media that can be used with coagulants,  but not with flocculants.

AFM grade 1 is equivalent to a standard 16 x 30 mesh size sand, however it will remove more than 97% of all particles in the water down to 4 microns,  this results was achieved at a velocity of 20m/hr.  hen the flow irate is reduced to 5m/hr performace approaches 100%.  AFM grade 1 can be used with coagulents and flocculents  in order to increase the performance in terms of solids and dissolved organic removal.

Differential Pressure V Injected Mass

injected mass

When filters are operated and solids are injected into the filter,  the differential pressure across the bed will increase.  After a few hours or days  the media bed filter will need to be back-washed.  However different types of media will have different capacities to hold on to the particles,  many filter media  will actually dump collected solids back into the water.  

If the pressure does not increase then is is a sign that the media is not actually removing very much from the water.  In this respect Vitrospheres gave a flat line and Garo was very similar. EGFM (DMS) and Astral were both unstable  and discharged solids back into the product water as evidenced by the  sudden drop in the graph.

Leighton Buzzard sand actually gave the best injected mass profile,  AFM matched the sand profile but at a slightly higher differential pressure.

  1. AFM® is an activated amorphous alumino-silicate with positive charge organic adsorption (OAD) number greater than 10, the activated hydrophilic surface has cation bridging, hydrogen bonding and entropic interactions with organic molecules.
  2. Surface area is 300 times high than crushed sand or glass for the adsorption of organic molecules, approx 1million
  3. High surface negative electrical charge density Zeta potential > -70mv as measured by kinetic analyser
  4. AFM® is certified under Regulation 31 in the UK
  5. AFM® is is compliance with European Water Directive (98/83/EC) & (80/778/EEC)
  6. AFM® manufactured under ISO9001-2008 quality procedures
  7. AFM® complies with BSEN12902 and BSEN 12904.
  8. Uniformity coefficient 1.4 to 1.5
  9. Sphericity factor better than 0.8

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