Ozone was first used in water treatment long time ago (about late 1800s) as it has a greater disinfection effectiveness against bacteria and viruses compared to other water treatment methods.
What is ozonation water treatment?
Ozonation water treatment is a process that uses ozone and its oxidizing properties to reduce the concentration of iron, manganese, sulfur, or eliminate taste and odor in the water. Ozone oxides the contaminants in the water to form insoluble metal oxides or elemental sulfur which are removed by post-filtration.
Ozone is colorless and unstable gas comprising of three oxygen atoms (O3), the ozone gas will readily degrade back to oxygen (O2) and a free oxygen atom (O) or free radical form. The free oxygen atom oxides the iron, manganese, and sulfur in the water to form insoluble metal oxides or elemental sulfur.
The ozonation process
Ozone can be created corona discharge simulation of the lightning (CD-type ozone generators) using an electric discharge field, or by ultraviolet radiation as simulation of the ultraviolet rays from the sun (UV-type ozone generators), ozone may also be made through electrolytic and chemical reactions.
In the ozonation system, ozone is created with a concentration of approximately 1% or 10,000 mg/L by passing the dry and clean air through a high voltage electric discharge (i.e., corona discharge).
Then, the air (with ozone) is bubbled up through the source water or the water is passed through a venturi throat which creates a vacuum and pulls the ozone gas into the water.
The ozone will react with the metals present in the water to create insoluble metal oxides, so post filtration is required to complete the water treatment process.
The advantages of ozone in water treatment
- Effects over a wide pH range.
- Rapidly reacts with bacteria, viruses, and protozoans.
- Has stronger germicidal properties than chlorination.
- Has a very strong oxidizing power with short reaction time.
- No chemicals added into the water.
- Ozone can eliminate a wide variety of inorganic, organic, microbiological, taste, and odor problems.
- Higher equipment and operational costs
- Difficult to find professional proficiency for system operating and maintenance.
- No germicidal or disinfection residual to inhibit or prevent regrowth.
- Ozonation products are still being evaluated.
- The system may require pre-treatment for hardness reduction
- Ozone is less soluble in water, compared to chlorine, special mixing techniques are required.
- Potential fire hazards and toxicity issues.