During the operation of sewage treatment plants, various chemicals are used to treat different types of pollutants, ensuring efficient sewage treatment processes and final effluent quality that meets discharge standards. The following are several commonly used chemicals and their functions in sewage treatment plants:
1. coagulants/coagulants:
Polyaluminum chloride (PAC): used to remove suspended solids and colloids in water, with good coagulation effect, suitable for various sewage treatment processes.
Polyferric sulfate: Similar to PAC, but with a wider pH range, it has good treatment effects for low temperature and low turbidity water, and also has phosphorus removal function.
Polyacrylamide (PAM): Used as a coagulant aid, it can increase the size and strength of flocs, accelerate precipitation, and improve separation efficiency. It is divided into anionic, cationic, and other types.
2. Conditioner:
Mainly used before sludge dewatering to help improve the dewatering performance of sludge, such as using specific types of PAM.
3. Demulsifier:
Used for treating oily wastewater, it can destroy emulsified oil droplets, cause them to condense and separate from water.
4. Defoamer:
Such as silicone, which is used to eliminate foam generated during aeration or mixing, to prevent foam overflow from affecting operation and treatment effect.
5. pH regulator:
Such as hydrochloric acid, sodium hydroxide, etc., are used to adjust the acidity and alkalinity of wastewater to a suitable range, ensuring that the chemicals used in subsequent treatment steps can work effectively.
6. Redox agent:
Such as chlorine dioxide, hydrogen peroxide, etc., are used to oxidize and decompose organic and reducing substances in wastewater, reducing COD (chemical oxygen demand) and BOD (biochemical oxygen demand).
7. Disinfectant:
Such as chlorine gas and ozone, used to kill pathogenic microorganisms in water and ensure the hygiene and safety of effluent.
8. Scale inhibitor:
MDC series scale inhibitors are used to prevent the formation of scale in treatment equipment and pipelines, and to maintain system operational efficiency.
9. Special treatment agents:
Specialized adsorbents, chelating agents, etc. may be required for specific pollutants such as heavy metals, dyes, etc.
The use of these agents needs to be customized according to the specific design of the sewage treatment plant, the quality of the incoming water, and the final treatment requirements, with reasonable dosage and combination to achieve the best treatment effect and economic benefits.
