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1. Introduction to Chemicals in Water Treatment
Water treatment relies heavily on a range of chemicals to remove impurities, prevent contamination, and ensure water safety. These chemicals serve specific roles such as coagulation, disinfection, pH adjustment, and corrosion control. Understanding their properties and proper application is essential for effective water management in both municipal and industrial systems.
2. Coagulants and Flocculants
Coagulants and flocculants are critical in the physical treatment process. They help aggregate suspended particles and colloids, making them easier to remove during sedimentation or filtration.
2.1 Common Coagulants
- Aluminum Sulfate (Alum): Widely used to destabilize suspended particles and aid in sedimentation.
- Ferric Chloride: Effective for turbid water and industrial wastewater with high organic content.
- Polyaluminum Chloride (PAC): Provides faster floc formation and improved clarity.
2.2 Flocculants
- Polyacrylamide (PAM): Enhances the aggregation of flocs formed during coagulation.
- Natural Polymers: Such as chitosan, useful for environmentally friendly water treatment.
3. Disinfectants
Disinfection is essential to eliminate pathogenic microorganisms. Different chemicals are selected based on water type, residual requirement, and safety standards.
3.1 Types of Disinfectants
- Chlorine: Effective against bacteria, viruses, and algae; commonly used in municipal water treatment.
- Chloramines: Provide longer-lasting disinfection in water distribution systems.
- Ozone: Powerful oxidant for industrial water treatment and swimming pools.
- UV Radiation: Non-chemical method to inactivate microorganisms.
4. pH Adjusters and Corrosion Inhibitors
Maintaining the correct pH and preventing corrosion in pipes and storage tanks are essential for long-term water safety and infrastructure protection.
4.1 Common pH Adjusters
- Lime (Ca(OH)₂): Raises pH and precipitates hardness-causing minerals.
- Sodium Hydroxide (NaOH): Strong base used for industrial water pH control.
- Carbon Dioxide (CO₂): Lowers pH in high-alkalinity water.
4.2 Corrosion Inhibitors
- Phosphates: Form protective layers on metal surfaces.
- Silicates: Used to prevent pipe scaling and corrosion simultaneously.
5. Summary Table of Key Water Treatment Chemicals
| Chemical Type | Examples | Primary Function |
| Coagulants | Alum, Ferric Chloride, PAC | Particle aggregation and sedimentation |
| Flocculants | Polyacrylamide, Chitosan | Enhance floc formation |
| Disinfectants | Chlorine, Ozone, UV | Kill or inactivate pathogens |
| pH Adjusters | Lime, NaOH, CO₂ | Regulate water acidity/alkalinity |
| Corrosion Inhibitors | Phosphates, Silicates | Protect pipes and infrastructure |
