I. Product Overview

High-chroma wastewater widely originates from industries such as textile printing and dyeing, dye production, papermaking and pulping, ink manufacturing, pharmaceutical intermediates, food fermentation, and chemical synthesis. This wastewater contains numerous chromogenic groups (such as azo bonds, nitro groups, imine groups, quinone groups, and conjugated double bonds) and auxochromic groups, resulting in colors ranging from deep red, orange-yellow, blue-black, to purplish-brown, with chromaticity typically hundreds to tens of thousands of times higher. This type of wastewater not only has a poor visual appearance, but the chromogenic organic matter often possesses biotoxicity or is difficult to biodegrade. When discharged into receiving water bodies, it obstructs sunlight transmission and disrupts the aquatic ecological balance.

Traditional decolorization methods each have their limitations: flocculation and sedimentation produce large amounts of chemical sludge and have poor decolorization effects on water-soluble dyes; activated carbon adsorption is costly, difficult to regenerate, and produces saturated carbon hazardous waste; ozone oxidation requires large equipment investment, has low ozone utilization, and high operating power consumption; Fenton oxidation consumes large amounts of reagents, produces a large amount of iron sludge, and requires repeated pH adjustments; biological methods have almost no ability to degrade most synthetic dyes, and color cannot be removed biochemically.

This system employs electrochemical oxidation technology. It directly oxidizes the chromophores at the unsaturated bonds and conjugated structures of the chromophores through anodic oxidation, while simultaneously using electrocatalysis to generate hydroxyl radicals (·OH) and strong oxides such as active chlorine for indirect oxidation. This completely breaks down or transforms the chromophores into colorless small molecules. The entire process consumes only electricity, requires no chemical reagents, and produces no sludge or saturated waste. The decolorization rate can reach 90%–99%, reducing color to less than 50 times the original value, while simultaneously removing COD, resulting in colorless and transparent effluent.

II.Difficulties in treating high-color wastewater and solutions of this equipment

III. Working Principle

High-chroma wastewater, after having suspended solids removed by a screen or filter, enters an electrochemical reactor, where, under the action of electrodes:

(1) Direct electro-oxidation

Chromophores (azo bonds, quinone structures, conjugated double bonds, aromatic rings, etc.) directly lose electrons at the anode surface, breaking unsaturated bonds in the molecular structure, disrupting the conjugated system, and raising the electronic transition energy level beyond the visible spectrum, macroscopically manifesting as color loss. This pathway is highly selective for dye molecules and is the most important mechanism for decolorization.

(2) Indirect electro-oxidation

The anodic electrolysis of water generates hydroxyl radicals (·OH), while naturally occurring chloride ions in the wastewater (commonly found in industries such as dyeing and printing) are electrolyzed to produce active chlorine (Cl₂, HOCl, OCl⁻). These highly oxidizing active species diffuse into the solution, subjecting dye molecules that have not directly contacted the anode to secondary oxidative attack, further breaking down residual chromophores and mineralizing organic intermediates.

(3) Co-removal of COD

After the chromophores are broken, the resulting small organic molecules (such as organic acids and alcohols) continue to be oxidized and mineralized into CO₂ and H₂O, simultaneously achieving a significant reduction in COD. The total amount of organic matter in the decolorized effluent decreases significantly, rather than simply "bleaching" the chromophores while keeping the COD unchanged.

(4) Anti-chromaticity rebound mechanism

Electrochemical oxidation causes complete molecular restructuring of the chromophores, rather than merely altering the distribution of electron clouds around the chromophores. After treatment, the wastewater shows no visible color recovery after 24-72 hours of standing, ensuring the long-lasting stability of the decolorization effect.

IV. Core Advantages (for high-color wastewater)

V. Technical Specifications (Customizable)

VI. Applicable to various scenarios involving high-color wastewater.

VII. Process Location

Option 1: Separate decolorization treatment (directly meets emission standards or is reused)High-chroma wastewater → Screening/sedimentation (removal of suspended solids, fibers, etc.) → Electrochemical equipment → Effluent (colorless and transparent, COD meets standards) → Discharge or reuse in production

Option 2: Pretreatment followed by biochemical treatment (applicable to high-concentration composite wastewater)

High-chroma wastewater → Screening/sedimentation → Electrochemical equipment (decolorization, elimination of biotoxicity, improvement of B/C ratio) → Biological system → Discharge meeting standards

Note: After electrochemical destruction of the chromogenic organic matter, the B/C ratio is significantly improved (the B/C ratio of some dye wastewater can be increased from 0.1 to over 0.3). The subsequent biochemical system can efficiently degrade the residual small molecule organic matter. The electrochemical stage aims at "decolorization + detoxification" while keeping power consumption at a low level.

Option 3: As an advanced treatment unit (for decolorization and standard improvement of biochemical effluent)

Biochemical treatment → Secondary sedimentation tank → Electrochemical decolorization equipment → Discharge

Note: The color of some wastewater treated by biological treatment still does not meet the standards (biological treatment has little effect on removing chromophores). Adding an electrochemical decolorization unit at the end of the biological treatment process, which operates at low power and only treats residual color, has the lowest operating cost and is an ideal supplement to the existing biological treatment system for upgrading.