The colour caused by organic molecules or substances in water starts to lose its effect by being broken down as soon as it comes into contact with ozone.
Due to the strong oxidant nature of ozone gas, the success of colour and odor removal methods in drinking water has led to an important market in waste water treatment.
Ozone systems are very low operating costs, no personnel costs. Ozone systems provide 85-98% success in colour removal and 40-55% success in COD removal.
Today, ozone applications in many countries of the world paint, textile, pharmaceuticals and so on. is one of the preferred methods in industrial plants. Ozone is used as “bleach in pulp and paper production, kaolin production and textile production in addition to the applications mentioned above.
The quality of the ozone treatment effluent in terms of colour removal, depends on:
- the colour values of the feed
- the ozone dosage
- the wastewater type (Typically colour values do not decrease below 200 Pt-Co units even if an especially high ozone dosage is applied)
- the wastewater temperature (better results with effluent from the existing treatment whose temperature is much lower than the temperature of wastewater from the equalization tank)
- the values of the other wastewater characteristics that ozone also affects (better results if BOD, COD and SS have already been decreased in a previous treatment level)
The best results concerning colour removal are achieved if the wastewater has been previously treated in order to lower the values of the other characteristics so that the ozone oxidizing effect is “consumed” only or at least at a maximum proportion in colour removal. Additionally the temperature must be below 30-deg C in order to achieve the best physical conditions for its solubility.