Chemical coagulation is the process used to remove colloidal particles from water. It involves the addition of chemicals that destabilize the colloidal particles, causing them to clump together and form larger particles, which can then be easily removed through sedimentation or filtration.

Here is a detailed explanation of the process:

1. Introduction to Colloidal Particles in Water:
- Colloidal particles are small particles suspended in water, ranging in size from 1 to 100 nanometers.
- They are too small to settle under gravity and are resistant to filtration.
- Colloidal particles can cause turbidity in water and may carry impurities such as organic matter, bacteria, and viruses.

2. Chemical Coagulation:
- Chemical coagulation is a widely used method to remove colloidal particles from water.
- Coagulants, such as aluminum sulfate (alum) or ferric chloride, are added to the water.
- These coagulants neutralize the surface charge of colloidal particles, causing them to destabilize.

3. Destabilization of Colloidal Particles:
- Colloidal particles have a negative surface charge due to ionization of functional groups on their surface.
- The coagulant ions neutralize this charge, reducing the repulsive forces between particles.
- As a result, the particles come closer together, allowing attractive forces (van der Waals forces) to act between them.

4. Formation of Coagulation Flocs:
- The attraction between particles leads to the formation of larger aggregates called coagulation flocs.
- These flocs continue to grow as more particles are incorporated into them.
- The size and strength of the flocs depend on various factors such as coagulant dosage, pH, and mixing intensity.

5. Settling or Filtration:
- Once the colloidal particles have formed larger flocs, they can be removed from the water through sedimentation or filtration.
- Sedimentation involves allowing the flocs to settle under gravity in a settling tank, where they form a sludge layer at the bottom.
- Filtration can be used to remove smaller flocs that may not settle effectively.
- The filtered water is then further treated to remove any remaining impurities.

In conclusion, chemical coagulation is an effective method for removing colloidal particles from water. It involves the addition of coagulants to destabilize the particles, leading to the formation of larger flocs that can be easily removed through sedimentation or filtration.