In a municipal water treatment plant, raw water with high organic content is chlorinated. The operator observes that after adding chlorine, the free residual chlorine initially rises, then falls, and then rises again with further chlorination. The point at which free residual chlorine begins to rise again after the dip is called:
- A Breakpoint ✓
- B Chlorine demand
- C Chlorine residual
- D Superchlorination point
Correct answer: A. Breakpoint
Explanation
The breakpoint is the point on the chlorination curve where further addition of chlorine results in a proportional rise in free residual chlorine, indicating that ammonia and organic matter have been oxidized. Chlorine demand is the difference between applied and residual chlorine. Superchlorination is adding excess chlorine for rapid disinfection. The breakpoint ensures effective disinfection with free chlorine.
Reference: Park's Textbook of Preventive and Social Medicine, 26th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
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