Chemical wastewater refers to the wastewater discharged from the production process of every chemical product, including process wastewater, cooling water, waste gas washing water, equipment and field pool flushing water, etc.

Characteristics of chemical wastewater:

1. Toxic and irritating, chemical wastewater contains many pollutants, some of which are toxic or highly toxic substances such as cyanide, phenol, arsenic, mercury, cadmium, and lead;

2. Both BOD and COD are high, and chemical wastewater contains various organic acids, alcohols, aldehydes, ketones, ethers, and epoxides;

3. Unstable pH, wastewater discharged from chemical production sometimes exhibits strong acidity, sometimes strong alkalinity, and unstable pH;

4. There are many nutrients, and some of the wastewater from chemical production contains high levels of phosphorus and nitrogen;

5. The wastewater temperature is relatively high, and due to chemical reactions often occurring at high temperatures, the discharged wastewater has a higher water temperature;

6. Oil pollution is relatively common, and petroleum and chemical wastewater generally contains oil;

7. It is difficult to restore water bodies contaminated with harmful chemical substances. Even if the discharge of pollutants is reduced or stopped, it still takes a long time to restore the water bodies to their original state.

Today, I will talk about the COD treatment methods for chemical wastewater. Excessive COD in water is based on the excessive content of these organic substances, which can be treated through the following methods.

Treatment methods for chemical wastewater:

(1) Physical method: It uses physical actions to separate suspended solids or turbid substances in wastewater, which can remove COD from wastewater.

Common methods include grilling, sieving, centrifugation, clarification, filtration, and oil separation.

(2) Chemical method: It is the use of chemical reactions to remove dissolved or colloidal substances from wastewater, which can remove COD from wastewater.

Common methods include neutralization, precipitation, oxidation-reduction, catalytic oxidation, photocatalytic oxidation, microelectrolysis, electrolytic flocculation, incineration, etc.

(3) Physical chemistry method: It is the use of physical and chemical reactions to remove dissolved or colloidal substances from wastewater. Can remove COD from wastewater.

Common methods include grilling, sieving, centrifugation, clarification, filtration, and oil separation.

(4) Biological treatment method: It utilizes microbial metabolism to convert organic pollutants and inorganic microbial nutrients in wastewater into stable and harmless substances.

Common methods include activated sludge process, biofilm process, anaerobic digestion process, stable pond and wetland treatment, etc.