Ozone (O3) purifies water primarily by acting as a powerful oxidizing agent.
Here's a breakdown of how ozone is used in water purification:
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Oxidation: Ozone readily donates an oxygen atom, oxidizing a wide range of substances present in water. This oxidation process breaks down pollutants.
- Decolorization: Ozone oxidizes colored organic compounds, removing discoloration from the water.
- Odor and Taste Removal: It destroys organic molecules that cause unpleasant odors and tastes.
- Organic Compound Degradation: Complex organic pollutants are broken down into simpler, less harmful substances, and in some cases, completely mineralized (converted to CO2 and H2O).
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Disinfection: Ozone is a highly effective disinfectant, far more potent than chlorine in inactivating bacteria, viruses, and protozoa. It disrupts the cellular processes of these microorganisms, rendering them harmless. Unlike chlorine, ozone disinfection produces fewer harmful byproducts.
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Microflocculation: Ozone can aid in the coagulation of small particles, making them easier to filter out.
Ozone Generation:
For industrial water treatment, ozone is typically generated on-site using one of two methods:
- Ultraviolet (UV) Light: UV light at a specific wavelength (typically 185 nm) splits oxygen molecules (O2) into single oxygen atoms (O). These atoms then combine with other oxygen molecules to form ozone (O3). This method is generally used for smaller applications.
- Corona Discharge: Oxygen-containing gas (either pure oxygen or dry air) is passed through a high-voltage electrical field. This "corona discharge" splits oxygen molecules, and the resulting oxygen atoms combine to form ozone. This is the more common and efficient method for larger-scale water treatment plants.
Benefits of Ozone Water Purification:
- Effective disinfection and oxidation.
- Elimination of odors and tastes.
- Reduced formation of harmful disinfection byproducts compared to chlorination.
- Effective over a wide pH range.
- Leaves no residual taste or odor in the treated water (ozone quickly decomposes back into oxygen).
Drawbacks of Ozone Water Purification:
- Ozone must be generated on-site, as it is unstable and cannot be stored.
- Higher initial investment compared to some other water treatment methods.
- Does not provide a disinfectant residual in the water distribution system (which can be desirable to prevent regrowth of microorganisms).
