Which component is commonly used as a coagulant and affects particle charge?

Which component is commonly used as a coagulant and affects particle charge?

• A. Alum (aluminum sulfate).
• B. Chlorine.
• C. Sand.
• D. Activated carbon.

Answer: (A)

Coagulation works by changing the electrical charge on particles so they don’t repel each other and can come together to form larger clumps. Natural waters often have tiny particles with negative charges on their surfaces. Adding a coagulant with a positive charge neutralizes those negative charges, letting particles come together into flocs that can be settled out or filtered more easily. The most common coagulant is alum (aluminum sulfate), which hydrolyzes in water to form aluminum hydroxide flocs that help neutralize charge and link particles into aggregates. This is why alum is the best choice for a coagulant that affects particle charge. Chlorine is used for disinfection, sand is a filtration medium, and activated carbon adsorbs organics and improves taste/odor, but they don’t primarily change particle charge to promote coagulation.

Coagulation works by changing the electrical charge on particles so they don’t repel each other and can come together to form larger clumps. Natural waters often have tiny particles with negative charges on their surfaces. Adding a coagulant with a positive charge neutralizes those negative charges, letting particles come together into flocs that can be settled out or filtered more easily. The most common coagulant is alum (aluminum sulfate), which hydrolyzes in water to form aluminum hydroxide flocs that help neutralize charge and link particles into aggregates. This is why alum is the best choice for a coagulant that affects particle charge. Chlorine is used for disinfection, sand is a filtration medium, and activated carbon adsorbs organics and improves taste/odor, but they don’t primarily change particle charge to promote coagulation.