Which statement about overdosing coagulants is true?

Which statement about overdosing coagulants is true?

• A. It can adversely affect coagulation efficiency and lead to head loss buildup
• B. It has no effect
• C. It reduces head loss
• D. It always improves removal

Answer: (A)

Overdosing coagulants disrupts the way coagulation works and tends to raise the solids load in the system. When too much coagulant is added, particles can become restabilized or acquire a net charge that makes them harder to aggregate into larger flocs. That means poorer coagulation efficiency and weaker floc formation, so more suspended solids pass through and load the downstream filters. The extra solids clog filter media and increase the head loss, meaning flow is more restricted and backwashing may be needed more often. So this situation both harms removal effectiveness and increases head loss. The other ideas—no effect, reduced head loss, or guaranteed improvement in removal—don’t reflect what actually happens with over-dosing.

Overdosing coagulants disrupts the way coagulation works and tends to raise the solids load in the system. When too much coagulant is added, particles can become restabilized or acquire a net charge that makes them harder to aggregate into larger flocs. That means poorer coagulation efficiency and weaker floc formation, so more suspended solids pass through and load the downstream filters. The extra solids clog filter media and increase the head loss, meaning flow is more restricted and backwashing may be needed more often. So this situation both harms removal effectiveness and increases head loss. The other ideas—no effect, reduced head loss, or guaranteed improvement in removal—don’t reflect what actually happens with over-dosing.