What are the methods for treating COD in chemical industry wastewater?

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Chemical wastewater is the waste water discharged during the production of each chemical product, including process wastewater, cooling water, waste gas washing water, and water used for cleaning equipment and tanks. Characteristics of chemical industry wastewater: 1. Toxicity and irritancy – Chemical industry wastewater contains many pollutants, some of which are toxic or highly toxic substances such as cyanide, phenols, arsenic, mercury, cadmium, and lead. 2. High BOD and COD levels – Such wastewater contains various organic acids, alcohols, aldehydes, ketones, ethers, and epoxides. 3. Unstable pH – Wastewater generated from chemical production can be either strongly acidic or strongly alkaline, resulting in an unstable pH value. 4. High levels of nutrients – Some types of chemical industry wastewater contain high amounts of phosphorus and nitrogen. 5. High temperature of the wastewater – Since chemical reactions often take place at high temperatures, the wastewater discharged is also at a high temperature. 6. Common oil contamination – Petrochemical wastewater generally contains oils. 7. Difficult to restore – Water bodies contaminated by harmful chemicals from the chemical industry require a long time to return to their original state, even if the discharge of pollutants is reduced or stopped. Today, I would like to talk to you about the methods for treating COD in chemical industry wastewater. Excess levels of COD in water are caused by an excessive amount of these organic substances, and it can be treated using the following methods. Treatment methods for COD in chemical industry wastewater: (1) Physical methods: These involve using physical forces to separate suspended solids or emulsions from the wastewater, thereby removing COD from it. Common methods include: gridding, screening, centrifugation, clarification, filtration, and oil separation. (2) Chemical method: This involves using chemical reactions to remove dissolved or colloidal substances from wastewater, and it can eliminate COD from the wastewater. Common methods include: neutralization, precipitation, redox reactions, catalytic oxidation, photocatalytic oxidation, microelectrolysis, electrolytic flocculation, incineration, and others. (3) Physicochemical methods: These involve using physicochemical processes to remove dissolved substances or colloidal substances from wastewater. It can remove COD from wastewater. Common methods include: gridding, screening, centrifugation, clarification, filtration, and oil separation. (4) Biological treatment method: It utilizes the metabolic activities of microorganisms to convert organic pollutants and inorganic microbial nutrients in wastewater into stable and harmless substances. Common methods include: activated sludge process, biofilm process, anaerobic biological digestion, stabilization ponds, and wetland treatment. The image is from the Internet