Electrochemical wastewater treatment equipment, used for chemical wastewater.

Product Specification

Electrochemical wastewater treatment equipment, used for chemical wastewater.

I. Product Overview

Chemical wastewater is one of the most widespread, complex, and difficult-to-treat types of industrial wastewater, encompassing multiple sub-sectors including organic chemicals, inorganic chemicals, fine chemicals, petrochemicals, coal chemicals, fertilizers, polymer materials, chlor-alkali, dyes, coatings, pesticides, andbio‑chemical sectors. Its overall water quality characteristics are as follows: The wastewater contains a large amount of raw and auxiliary materials, intermediate products, by-products, and product residues used in the production process—including benzene compounds, phenols, alcohols, aldehydes, ketones, organic acids, esters, special organic components, polycyclic aromatic hydrocarbons, heterocyclic compounds, halogenated hydrocarbons, nitro compounds, organophosphorus compounds, polymer monomers, surfactants, organic solvents, and catalyst residues; some high-concentration process wastewater can reach tens to hundreds of thousands of mg/L; the wastewater often contains characteristic pollutants that inhibit or toxicize microorganisms; the salt content varies widely (from several hundred mg/L to over ten percent); the BOD₅/COD ratio generally fluctuates between 0.05 and 0.30, with significant differences in biodegradability; and the wastewater quality fluctuates significantly with changes in product type, production process, and production cycle.

The core challenges of treating chemical wastewater lie in several key areas: ① High proportion of recalcitrant organic matter – stable chemical structures such as aromatics, heterocyclic compounds, halogenated compounds, and nitro groups exhibit high tolerance to conventional microorganisms, making effective degradation by biological systems difficult. ② Significant biotoxicity issues – various chemical intermediates and byproducts inhibit or even kill activated sludge microorganisms, leading to frequent impacts on biological systems, low treatment efficiency, and even system collapse. ③ High salinity exacerbates treatment difficulties – some chemical wastewaters contain 3%–10% salt (e.g., chlor-alkali, pesticide synthesis, pharmaceutical intermediates), and the high osmotic pressure makes it difficult for conventional activated sludge microorganisms to survive. ④ Drastic fluctuations in water quality and quantity – under multi-product, intermittent production models, the concentration of COD and toxic substances in wastewater can change several times to tens of times within hours, making it difficult for traditional biological systems to respond quickly.

This system employs electrochemical oxidation technology, utilizing the synergistic effect of direct anodic oxidation and strong oxides such as hydroxyl radicals (·OH) and active chlorine generated by electrocatalysis to directly attack various stable chemical structures in chemical wastewater. It can be flexibly applied to different stages of chemical wastewater treatment:

Pretreatment Detoxification:Directly treats high-concentration wastewater, rapidly oxidizing and decomposing recalcitrant and toxic structures such as aromatic rings, heterocyclic rings, halogenated groups, and nitro groups, significantly reducing COD and increasing the B/C ratio to above 0.30, creating safe and biodegradable influent conditions for subsequent biological systems.

High-Salinity Organic Wastewater Pretreatment: After removing COD and color, the wastewater enters the evaporation and crystallization system, improving the quality of crystallized salts and significantly reducing the discharge of evaporation mother liquor.

High-Concentration Wastewater Reduction:Treats small volumes of wastewater with COD in the tens of thousands of mg/L on-site, significantly reducing COD before being incorporated into the plant's integrated system, replacing costly hazardous waste transportation and disposal.

The entire process consumes only electricity, without adding any chemical reagents. The electrodes are adaptable to complex chemical wastewater conditions such as high salinity, high COD, and oil content, operating safely and stably at normal temperature and pressure. By rapidly adjusting the current parameters, it can respond to drastic fluctuations in the quality of chemical wastewater within minutes, without the need for long-term acclimatization and waiting of biochemical systems. This is a key technical solution to address the four core Key difficulties of chemical wastewater: "difficult to degrade, highly toxic, highly volatile, and high treatment costs".

II. Difficulties in chemical wastewater treatment and solutions of this equipment

III. Working Principle

After suspended solids are removed by screens, sedimentation, or filtration (some high-concentration wastewater requires simple pretreatment), chemical wastewater enters an electrochemical reactor, where the following purification reactions occur under the action of electrodes:

(1) Direct electro-oxidation (the core pathway of ring-opening and bond breaking of recalcitrant organic matter)

A large amount of recalcitrant organic matter in chemical wastewater loses electrons directly on the anode surface and is oxidized:

Aromatic compounds (benzene, typical aromatic components, xylene, naphthalene, biphenyl, phenol, aniline, etc.): Aromatic rings are hydroxylated by active oxygen species on the anode surface and then open, transforming into small molecule organic acids (maleic acid, oxalic acid, acetic acid, etc.), greatly improving their bioavailability.

Heterocyclic compounds (pyridine, quinoline, thiazole, furan, imidazole, indole, etc.): Heterocyclic rings containing N/S/O are oxidized and opened on the anode surface, eliminating the cyclic biotoxicity.

Halogenated compounds (chlorobenzene, chloroform, carbon tetrachloride) , brominated compounds, etc.): C-X bonds break on the anode surface, and halogens are removed in ionic form. Nitro compounds (nitrobenzene, nitrobenzene, dinitro compounds, etc.): Nitro groups are removed by oxidation/reduction, benzene rings open, and mutagenicity is eliminated. Polycyclic aromatic hydrocarbons (naphthalene, anthracene, phenanthrene, etc.): Aromatic ring systems are gradually oxidized and opened, and polycyclic structures are decomposed into monocyclic or small molecules. Organophosphorus compounds: P-C bonds are oxidized and broken, and organophosphorus is converted into orthophosphate. Polymers/macromolecular organics (polyethylene glycol, polyacrylic acid, resin fragments, etc.): Long carbon chains andether‑group molecular structures are oxidized and broken.

(2) Indirect electro-oxidation (broad-spectrum oxidation dominated by ·OH and active chlorine) Anode electrolysis of water generates hydroxyl radicals (·OH), while utilizing naturally occurring chloride ions in wastewater (most chemical wastewater contains Cl⁻, with a concentration range of 200~20000). Electrolysis of mg/L generates active chlorine (Cl₂, HOCl, OCl⁻): Hydroxyl radicals perform non-selective oxidative attacks on various organic compounds, especially effective in opening aromatic rings and breaking heterocyclic rings. Activated chlorine diffuses into the solution, supplementing the oxidation of pollutants that cannot directly contact the anode, and efficiently removing ammonia nitrogen.

(3) Simultaneous improvement of COD reduction and biodegradability: Synergistic effect of direct and indirect oxidation: Large molecule recalcitrant organic matter → ring opening/bond breaking/dehalogenation/denitrification → small molecule organic acids, alcohols, aldehydes → some further mineralized into CO₂ + H₂O. The BOD₅ of the treated effluent increases significantly (large molecules are converted into small molecule degradable substances), COD decreases simultaneously, and the B/C ratio increases significantly, providing a high-quality degradable carbon source for subsequent biochemical systems.

 (4) Deactivation Effect of Toxic Functional Groups: The core objective of electrochemical oxidation is to precisely attack toxic functional groups and deactivate them—the nitro group in nitrobenzene is removed, the C-X bond in halogenated compounds is broken, heterocycles open to release N, and the P-C bond in organophosphorus compounds is broken. Once the toxic groups are destroyed, even if the molecular skeleton is not completely mineralized, its inhibitory effect on microorganisms is essentially eliminated.

(5) Color Elimination: When chromophores are oxidized and broken, the wastewater changes from dark to colorless or light-colored and transparent.

IV. Core Advantages (Targeting Chemical Wastewater)

V. Technical Parameters (Customizable)

VI. Process Location

Option 1: Pretreatment and Detoxification

Chemical wastewater (raw water/combined water) → Bar screen/equalization tank → Sedimentation/flotation (SS and oil removal) → Electrochemical detoxification equipment (open-loop bond breaking, removal of toxic functional groups, B/C ratio improvement) → Intermediate tank/buffer tank → Biological system (hydrolysis acidification + A/O or A²/O) → Discharge meeting standards

Note: The electrochemical detoxification unit is the core guarantee for the pre-biological treatment of chemical wastewater. Chemical wastewater that has not undergone electrochemical detoxification directly enters the biological treatment system, resulting in a large amount of recalcitrant and toxic substances, reducing the COD removal rate of the biological system to only 50%~70%, and subjecting it to frequent shocks. After detoxification, the effluent B/C ratio is ≥0.30~0.35, the COD removal rate of the biological treatment stage is increased by 40%~70%, and the entire system operates stably and reliably throughout the year.

Option 2: Advanced Treatment to Meet Standards (For cases where COD in biochemical effluent still fails to meet standards)

Chemical wastewater → Pretreatment → Biochemical system → Secondary sedimentation tank → Electrochemical advanced treatment unit (removes residual stubborn COD and color) → Discharge meeting standards/Reuse

Note: When COD and color in the biochemical effluent still fail to meet discharge standards, an electrochemical advanced treatment unit is added after the biochemical system.

Option 3: High-Concentration Wastewater Reduction

High-concentration wastewater/mother liquor → Collection tank → Electrochemical treatment equipment → Effluent flows into the plant's integrated wastewater system → Conventional treatment

Option 4: High-Salinity Wastewater Pre-Evaporation Treatment

High-salinity chemical wastewater → Electrochemical pretreatment equipment (removes COD and color) → Evaporation crystallization system (MVR/multi-effect) → High-whiteness industrial salt + condensate reuse

Note: Direct evaporation of high-salinity mother liquor results in COD and color enrichment, large-scale discharge of mother liquor, and yellowing of the crystallized salt. Electrochemical pretreatment removes 50%~80% COD and ≥90% color before evaporation, resulting in white crystalline salt and a significant reduction in mother liquor discharge, thus realizing the resource utilization of high-salt wastewater.