Decolorizers can effectively remove color and pollutants through chemical oxidation, adsorption bridging and flocculation sedimentation in industrial wastewater treatment, while reducing indicators such as COD and BOD. They are one of the key technologies for meeting current industrial environmental protection standards. Combined with the increasingly stringent environmental protection policies and the background of the "dual carbon" goals, their role and advantages are analyzed as follows:

Ⅰ. The core mechanism of decolorizing agents

1. Chemical oxidation decolorization

• Oxidative decolorizing agents (such as H₂O₂, O₃, hypochlorite) mineralize or convert organic matter into colorless substances by destroying the dye chromophores (such as azo bonds, anthraquinone structures), and the decolorization rate can reach more than 95%.

• Case: Fenton oxidation method treats printing and dyeing wastewater (pH=3, H₂O₂ dosage 0.5%), decolorization rate>95%, COD removal rate 80%.

2. Adsorption and flocculation synergy

• Organic polymer decolorizers (such as quaternary ammonium salt polymers, dicyandiamide formaldehyde resins) neutralize anionic dyes in wastewater through cationic charges, and use molecular chain bridging to form high-density flocs for rapid sedimentation and separation.

• For example: LH decolorizer can polymerize suspended matter into "large volume, fast sedimentation" flocs, and simultaneously remove color, SS and COD.

II. Analysis of technical advantages

(1) High efficiency and broad spectrum

• Broad spectrum application: It is effective for soluble pigments such as reactive dyes, acid dyes, and disperse dyes, and can tolerate high-salt and high-organic concentration wastewater.

(2) Economical and easy to operate

• Low cost: The cost of treating a ton of water is lower than that of traditional biological methods, and no large equipment or high energy consumption is required (such as only a dissolving tank and a dosing pump are required).

• Fast response: Directly add the original solution or prepare a 0.1%-0.5% solution for use, and flocculation and sedimentation will be completed within 30 minutes, which is suitable for emergency treatment.

• Compatible with existing processes: It can be used in combination with coagulants such as PAM (add decolorizer first, then PAM) to improve efficiency and reduce the total consumption of reagents.

(3) Environmental protection and safety

• No secondary pollution: After bleaching, the flocs are dense, there is no suspended residue, and the pipeline is not blocked; the product is harmless and meets the emission standards.

• Equipment-friendly: The pH adaptability range is wide (acidic to alkaline wastewater), and it is non-corrosive to metal equipment.

Ⅲ.Core value under the current industrial environmental protection situation

1. Responding to strict emission standards

• The 2025 "Water Pollutant Emission Standards" strengthen the chromaticity and COD limits, and traditional processes are difficult to stably meet the standards. Decolorizers, as deep treatment units, can quickly meet new regulations (such as reducing the chromaticity of papermaking wastewater from 500 times to less than 5 times).

2. Support the realization of "dual carbon" goals

• Compared with high-carbon footprint technologies such as high-temperature incineration and membrane separation, decolorizers operate at room temperature and have low energy consumption, reducing indirect carbon emissions in the processing link.

3. Promote circular economy

• Some decolorizers (such as adsorption resins) can be recycled and regenerated to reduce solid waste production; treated wastewater can be reused in the production link to achieve resource circulation.

IV. Application points and trends

• Accurate selection: Oxidative decolorizers (such as O₃) are suitable for high-color wastewater; flocculation decolorizers (such as quaternary ammonium salt polymers) are suitable for colloid-containing wastewater.

• Green substitution trend: Develop bio-based decolorizers (such as microbial flocculants) to further reduce ecotoxicity, in line with the needs of sustainable chemical development.

In the context of industrial environmental protection shifting from "end-of-pipe treatment" to "full-process control", decolorizers, with their high efficiency, economy and flexibility, have become the core technology for enterprises to cope with compliance pressure and reduce costs and increase efficiency. In the future, with the integration of green chemistry and intelligent control, its application depth will be expanded from meeting emission standards to recycling of water resources, promoting the realization of the goal of near-zero discharge of industrial wastewater.