The chromaticity of water is an indicator for quantitative color measurement of natural water or various types of treated water.

Natural water often displays different colors such as light yellow, light brown, or yellow-green. The reason for producing color is due to humic, organic, or inorganic substances that are soluble in water. In addition, when water bodies are polluted by industrial wastewater, they also exhibit different colors.

Water color often affects the quality of industrial products such as paper making and textiles. Various uses of water have certain requirements for chromaticity: for example, the chromaticity requirement for domestic water is less than 15 °, the chromaticity requirement for paper industry water is less than 15 ° - 30 °, the chromaticity requirement for textile industry water is less than 10 ° - 12 °, and the chromaticity requirement for dyeing water is less than 5 °.

How to decolorize wastewater? There are mainly the following methods:

Decolorization flocculant method:

Select inorganic flocculants and organic anionic flocculants, prepare an aqueous solution, and add it to the wastewater. This will create a compressed double electric layer, which will cause the suspended particles in the wastewater to lose stability. The colloidal particles will agglomerate with each other to increase the particles, forming flocs and alum flowers. When the flocs grow to a certain volume, they will separate from the aqueous phase and precipitate, thereby removing a large amount of suspended solids in the wastewater, achieving a treatment effect. It is a new type of organic polymer flocculant that integrates decolorization, flocculation, and COD removal. This method is mainly used for the decolorization treatment of high chromaticity wastewater from dye factories, and can also be used for the decolorization treatment of wastewater from textile, chemical, coking, papermaking, printing and dyeing, bleaching, leather, urban sewage, and industrial sewage stations. It is used in conjunction with other related products, with better results.

Activated carbon adsorption method:

Activated carbon is a type of very small carbon particles with a large surface area, and there are even finer pores in the carbon particles. These pores can adsorb pollutants in suspended state in sewage water, and these pollutants fill the gaps between activated carbon. The larger the particle size of activated carbon, the larger the space that can accommodate suspended solids, the stronger the capacity to absorb pollutants, and the better the treatment effect. It has unique removal capabilities for organic substances represented by comprehensive indicators such as BOD and COD in wastewater, such as synthetic dyes, surfactants, phenols, benzenes, organochlorine, pesticides, and petrochemical products, and is one of the main methods for secondary or tertiary treatment of industrial wastewater.

Ozone oxidation decolorization method:

Ozone is a strong oxidant with a high oxidation potential. Such elements can strongly attract electrons, oxidize each other, and reduce themselves. Organic wastewater contains chromogenic groups such as diazo, azo, or cyclic compounds with benzene rings. The strong oxidation characteristics of ozone can destroy the cyclic compounds such as benzene, naphthalene, and anthracene that form the chromogenic groups, thereby decoloring the wastewater. The ozone oxidation decolorization reaction is rapid, the process is relatively simple, and there is no secondary pollution. Where there are shortcomings, the ozone equipment consumes a large amount of power, and the treatment cost is on the high side.