Biological approach

Traditional water treatment tries to avoid disease transmission by using more and more chlorine, UVc irradiation or ozone. But the transmission of pathogens is a biological problem; it therefore needs a biological solution. The approach of the Dryden Aqua integrated water treatment system does exactly that: Instead of using more powerful disinfections and expensive equipment, we design a pool water treatment process that changes the water to make it difficult for viri, bacterium and parasites to live and to reproduce:

Prevent instead of killing!

  1. No substrate: As a consequence of our bio-resistant AFM® , bacterium have no substrate on which they can grow and multiply.
  2. No nutrients: We remove food for bacteria by advanced coagulation, flocculation and filtration. Bacterium cannot grow anymore.
  3. The lower the chlorine demand, the lower the disinfection by-products (DBP’s): DAISY filters almost everything out of the water and reduces the chlorine demand to the lowest level possible. The lower the chlorine oxidation demand, the lower the concentration of chlorine disinfection by-products in the water and in the air


DAISY consists of three integrated steps:

daisy en oe weiss

1   Filtration with the bio-resistant filter media AFM®

2   Best coagulation and flocculation with APF and ZPM

3   Enhanced oxidation with ACO and ZPM


Step 1: Filtration with AFM

AFM®  stands for Activated Filter Media, a revolutionary filter media made from green container glass, developed by marine biologist Dr. Howard Dryden. AFM®  exceeds the performance of quartz and glass sand by filtering 30 % - 50 % more organics and sub 5 micron particles out of the water. The catalytic properties on the surface of AFM®  make it self-sterilizing and bio-resistant, which means no biofilm is formed in the filter bed. This reduces the chlorine demand  and therefore the formation of harmful volatile disinfection by products such as THM’s, cyanogen chloride and trichloramine. Not only the chlorine smell but also the risk of getting infected by pathogens like Legionella or cryptosporidium, is greatly  reduced. The pool is healthier for people, especially children, safer for the environment and economical with crystal clear water. AFM®  has been successfully used in over 100‘000 public and private swimming pools worldwide.


Step 2: Best coagulation and flocculation with APF and ZPM

AFM® Grade 1 will remove particles down to 4 microns at a filtration speed of 20 m/h. When AFM®  is combined with a ZPM static mixer using APF (All Poly Floc), the nominal filtration will go down to 0,1 microns and much of the dissolved organic matter will also be removed. Dissolved organics such as urea, creatine and amino acids are responsible for 80 % of the chlorine demand.

Lower concentrations of organic matter mean lower chlorine demand and lower concentration of disinfection by-products (DBP’s)


Step 3: Enhanced oxidation with ACO and ZPM

Bacteria colonies protected by biofilm are very resistant to chlorine. The ZPM is a safety barrier against these bacteria flocs. By cavitation in the ZPM, nano-bubbles are formed which will smash the flocs into individual bacteria, which can now be easily oxidised by chlorine.

ACO acts as an oxidation catalyst and chlorine stabilizer in outdoor pools. With ACO, the natural disinfection power of the sun is significantly increased and chlorine is protected from photo oxidation.


Watch the video in other Languages: