High-quality water sources for municipal use are dwindling, forcing utilities to seek alternate sources. Many times, aesthetics are the only problem preventing the use of these alternate water sources for potable purposes. Due to its oxidizing power, ozone is used successfully to reduce aesthetically unpleasant color, taste and odor. It has also proven beneficial as a microflocculent, aiding in the filtration process. Colored water is typically caused by a combination of dissolved organic matter, which absorbs visible light, and suspended colloidal and particulate matter, which scatters light.
Apparent color is due to both light absorption and light scattering.
True color is exclusively caused by dissolved matter. Typically these materials are organic in nature and contain aromatic rings. Typical organics falling into this classification include humic and fulvic acid. Ozone effectively reduces true color. By reacting the unsaturated groups and cleaving the carbon-carbon double bonds within organic compounds, ozone produces aldehydes, ketones and acids, depending on the groups affected, the ozone dosage and contact conditions.