Identify the coagulant aids:
(A) Clay (B) Activated Silica (C) Polymers (D) Aluminium Sulfate (E) Ferric Sulfate
Choose the correct answer from the options given below:

Correct option is C

Coagulant aids are substances used to improve the efficiency of the coagulation process during water treatment. Their purpose is to enhance floc formation and improve settling. Here’s a breakdown:
1. Clay (A):
Used as a coagulant aid to add weight to flocs, improving settling.
2. Activated Silica (B):
Enhances the coagulation process by increasing the size and density of flocs.
3. Polymers (C):
Act as coagulant aids by binding small particles into larger flocs, making them easier to settle or filter.
4. Aluminium Sulfate (D):
Not a coagulant aid but a primary coagulant. Commonly known as alum, it neutralizes charge on particles to form flocs.
5. Ferric Sulfate (E):
Another primary coagulant, used for neutralizing particles and forming flocs directly.
Thus, Clay, Activated Silica, and Polymers (A, B, and C) qualify as coagulant aids, while Aluminium Sulfate and Ferric Sulfate are primary coagulants.
Information Booster: 1. Coagulant vs. Coagulant Aid:
· Coagulants: Directly neutralize charges (e.g., Aluminium Sulfate, Ferric Sulfate).
· Coagulant aids: Improve the settling process (e.g., Activated Silica, Polymers).
2. Commonly Used Coagulant Aids:
· Clay: Enhances sedimentation.
· Activated Silica: Used for improving floc formation.
· Polymers: Very effective in binding particles.
3. Role of Coagulant Aids:
· Increase floc size.
· Improve floc strength and density.
· Aid in turbidity removal.
4. Why Aluminium and Ferric Sulfates Are Not Aids:
· They act as primary coagulants by neutralizing negative charges on suspended particles.
Additional Knowledge: · (A) Clay: Widely used in conjunction with other aids to improve floc settling.
· (B) Activated Silica: Commonly used in low-turbidity water for better coagulation results.
· (C) Polymers: Include synthetic and natural types; effective in removing colloidal impurities.
· (D) Aluminium Sulfate: A standard coagulant in water treatment, particularly for turbidity and color.
· (E) Ferric Sulfate: Works well in both acidic and alkaline waters, often paired with lime.