I. Product Overview

Coal chemical wastewater mainly originates from coal coking, gasification, liquefaction, and coal-to-methanol and coal-to-olefins processes. Typical water quality characteristics include: high COD concentration (2000~15000 mg/L), high ammonia nitrogen concentration (200~2000 mg/L), large amounts of recalcitrant organic matter (phenols, polycyclic aromatic hydrocarbons, heterocyclic compounds), strong biological toxicity, extremely poor biodegradability (BOD₅/COD is usually below 0.2), large fluctuations in water quality, and high salinity.

Traditional treatment processes typically employ a long process combination of "pretreatment (oil removal, phenol removal, ammonia stripping) + biological treatment + advanced treatment," which has problems such as lengthy process flow, huge land area, biological system being prone to collapse due to toxicity inhibition, low operating efficiency in winter, large sludge production, and difficulty in consistently meeting discharge standards.

This system employs electrochemical oxidation technology. Coal chemical wastewater, after necessary pretreatment such as oil removal, hardening removal, and pH adjustment, enters the electrochemical reactor. Through direct anodic oxidation and indirect oxidation by strongly oxidizing active species generated by electrocatalysis, phenolic and heterocyclic toxic pollutants can be rapidly oxidized and decomposed within 1-2 hours, increasing the wastewater's BOD₅/COD ratio from 0.1-0.2 to over 0.35, completely eliminating biological toxicity and creating safe influent conditions for subsequent biological treatment systems. Alternatively, it can be directly treated to meet discharge standards without requiring a biological treatment stage.

No chemical reagents are required throughout the process, and no sludge or concentrated water is produced. The electrodes are designed to be resistant to pollution and scaling, making them suitable for the complex water quality of coal chemical wastewater with high hardness and high salinity.

II. Challenges in Coal Chemical Wastewater Treatment and Solutions from This Equipment

III. Working Principle

After pretreatment such as oil removal and sedimentation/filtration, coal chemical wastewater enters the electrochemical reactor, where the following reactions occur under the action of electrodes:

(1) Direct electro-oxidation

Phenols and heterocyclic compounds (such as pyridine, quinoline, carbazole, etc.) are directly oxidized on the anode surface, the benzene ring and heterocyclic ring are opened, and macromolecular organic matter is decomposed into small molecule organic acids or carbon dioxide. This pathway is particularly efficient for the removal of phenols and polycyclic aromatic hydrocarbons.

Indirect electro-oxidation (main pathway)

Chloride ions in wastewater (coal chemical wastewater typically contains 500~5000 mg/L Cl⁻) are electrolyzed at the anode to generate active chlorine. The active chlorine further oxidizes ammonia nitrogen into nitrogen gas, while simultaneously performing deep oxidation and degradation of phenols and heterocyclic compounds.

The anode simultaneously electrolyzes water to generate hydroxyl radicals (·OH), which act as a non-selective strong oxidant to indiscriminately oxidize and attack various organic pollutants, ensuring the complete elimination of biological toxicity in the effluent.

Synergistic effect

Ammonia nitrogen is oxidized into nitrogen gas, while COD is simultaneously degraded.

After organic matter is removed, its competitive interference with ammonia nitrogen oxidation is avoided, achieving efficient removal of both ammonia nitrogen and COD. A small amount of residual active chlorine in the effluent has an antibacterial protective effect on the subsequent biological system, preventing toxic bacteria from entering the biological tank. The treated effluent has a significantly increased BOD₅/COD ratio and can directly enter the biological system for further degradation; for low-concentration coal chemical wastewater, it can also be directly treated to meet discharge standards.

IV. Core Advantages (Targeting Coal Chemical Wastewater

V. Technical Specifications (Customizable)

VI. Applicable coal chemical industry segmentation scenarios

VII. Process Location

Option 1: Pretreatment and Detoxification

Coal chemical wastewater → Oil removal and sedimentation (removal of suspended oil and SS) → Electrochemical treatment equipment (removal of biotoxicity, improvement of B/C ratio) → Biochemical system (A/O or A²/O) → Advanced treatment (optional) → Discharge to meet standards/reuse

Note: Physical pretreatment such as oil removal and sedimentation is required before the electrochemical equipment to remove suspended solids and grease, protect the electrodes, and ensure treatment efficiency. Increasing the B/C ratio of the electrochemical effluent to above 0.35 can improve the COD removal rate of the subsequent biological system by more than 30%, and significantly enhance the overall process stability.

Option 2: Separate treatment (suitable for upgrading medium- and low-concentration coal chemical wastewater or biochemical effluent)

Coal chemical wastewater → oil removal and sedimentation → electrochemical treatment equipment → discharge in compliance with standards/reuse within the plant area

Note: Wastewater can be discharged directly after electrochemical treatment, without the need for a biological treatment system. It is especially suitable for upgrading existing biological treatment systems when the effluent ammonia nitrogen/COD exceeds the standards.