In a study done at the Mount Valerien plant in the suburb of Paris the following results were obtained:

1. Pre-ozonation of the raw water with 1.6 ppm of Ozone resulted in 83% removal of Algae. When 2.1 ppm of Ozone was applied, the removal rate was lower.

2. The combination of pre-ozonation and coagulation flocculation settling procedure improves the removal of Algae to 98.4%. The ozone dosage was 1.6 ppm, and the coagulant was 70 mg/l of Aqualenc (Aluminum salt).

3. With added filtration, 99.8% of Algae was removed. This effect is similar to the removal of turbidity. Secondary ozonation after the filtration is most beneficial for final sanitation.

4. When followed with Granular Activated Charcoal (GAC) filtration, better than 99.99% algae removal was achieved.

6. It has been observed that if the coagulant is held at 50 ppm, and the pre-ozonation dosage is increased to 2.6 ppm, the Algae removal will also be maximized.

7. The following Algae are more resistant and traces may still be found in the water after Ozone and GAC: Chlorophycae Chlamydomonas
  • Chlorophycae Chlamydomonas
  • Golenkinia
  • Diatomophycae Cyclotella
  • Cyanophycae Oscillatoria