What additives are used in water treatment plants

Water treatment plants use a variety of chemical aids to process raw water into potable water that meets drinking standards. Here are some common aids used in water treatment plants:

1. Coagulants: Used to aggregate tiny particles such as silt and other suspended solids in water, making them settle or form larger flocs for easy removal by filtration. Common coagulants include Polyaluminum Chloride (PAC), Ferric Sulfate (PFS), and Polyacrylamide (PAM).

2. Disinfectants: Used to kill or deactivate bacteria, viruses, and other microorganisms in water to ensure the microbial safety of the water supply. Common disinfectants include chlorine (chlorine gas, sodium hypochlorite, and chlorine dioxide) and ozone.

3. pH Adjusters: Used to adjust the pH level of water to optimize the effectiveness of water treatment processes (such as coagulation and filtration) and ensure that the pH of the water supply meets standards. Common pH adjusters include sodium hydroxide (to raise pH) and sulfuric acid (to lower pH).

4. Decolorizing Agents: Used to remove organic colorants in water and improve its appearance. Activated carbon is a common decolorizing agent.

5. Deodorizers: Used to remove odors from water, such as earthy and musty smells caused by algae or other organic matter.

6. Water Softeners: Used to reduce the hardness of water, i.e., to lower the content of calcium and magnesium ions in water, to prevent the formation of scale in pipes and household appliances.

7. Fluoridation: In some areas, water treatment plants may add fluoride to prevent dental caries.

8. Stabilizers: Used to prevent the excessive evaporation or decomposition of disinfectants during transportation, ensuring that the water supply retains its disinfecting effect until it reaches the consumer.

9. Corrosion Inhibitors: Used to reduce the corrosion of water on pipes during transportation, extending the service life of the pipes.

10. Oxidizing Agents: In addition to disinfection, oxidizing agents such as potassium permanganate and hydrogen peroxide can also be used to remove certain organic pollutants from water.

11. Phosphates: In some cases, phosphates can be used as corrosion inhibitors to reduce metal corrosion in pipes.

When selecting and using these aids, water treatment plants must comply with strict regulations and standards to ensure the safety and quality of the water supply. In addition, water treatment plants regularly monitor water quality to ensure that the treatment process is effective and that the water supply meets all relevant health and safety standards.