Identify the non-coagulant in water treatment chemicals Which of the following is not used as a chemical coagulant in conventional clarification?

Introduction / Context:
Clarification requires coagulants to destabilize colloids. Knowing which chemicals serve as coagulants vs. disinfectants or pH adjusters is vital in designing and operating treatment trains.

Given Data / Assumptions:

• Candidates include common water treatment chemicals.
• We must identify the one that is not a coagulant.

Concept / Approach:
Alum (Al₂(SO₄)₃) and iron salts (e.g., ferrous sulphate) are classic coagulants. Hydrated lime can enhance coagulation via pH adjustment and, in softening, precipitate hardness—often grouped within the coagulation/softening toolkit. Chloramine (formed from chlorine and ammonia), however, is a secondary disinfectant used for residual maintenance in distribution systems, not for coagulation.

Step-by-Step Solution:

Verification / Alternative check:
AWWA and standard methods list chloramination under disinfection, not coagulation.

Why Other Options Are Wrong:

Common Pitfalls:
Assuming all chemical additions prior to sedimentation are “coagulants.” Some, like lime, primarily adjust pH/alkalinity but are integral to coagulation performance.

Final Answer:
Chloramine