Question:medium
A student was asked to bring the correct boxes from lab for Nalgonda technique. Which pair is correct?
A student was asked to bring the correct boxes from lab for Nalgonda technique. Which pair is correct?
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Nalgonda technique for defluoridation uses alum and lime.
Updated On: May 14, 2026
- Alum and Gypsum
- Alum and Charcoal
- Alum and Lime
- Charcoal and Lime
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The Correct Option is C
Solution and Explanation
Step 1: Understanding the Question:
The Nalgonda technique is a chemical precipitation method used to de-fluoridate water. The question asks for the two primary chemical reagents used in the process.
Step 2: Detailed Explanation:
Origins: Developed by the National Environmental Engineering Research Institute (NEERI), Nagpur, specifically for de-fluoridation in endemic regions of India.
Required Chemicals:
Alum (Aluminum Sulfate): This acts as a coagulant. It leads to the precipitation of fluoride ions by forming aluminum-fluoride flocs.
Lime (Calcium Hydroxide/Oxide): Lime is added to maintain the appropriate pH for optimal flocculation and to help in the settling of the sludge. It also neutralizes the acidity produced by the alum.
Bleaching Powder: A small amount is sometimes added for concurrent disinfection, but Alum and Lime are the core components.
Process Sequence: Chemical addition $\rightarrow$ Rapid mixing $\rightarrow$ Flocculation $\rightarrow$ Sedimentation $\rightarrow$ Decantation. This can be done at both the household and community levels.
Step 3: Final Answer:
The Nalgonda technique primarily relies on the interaction of Alum and Lime to precipitate fluoride out of water.
The Nalgonda technique is a chemical precipitation method used to de-fluoridate water. The question asks for the two primary chemical reagents used in the process.
Step 2: Detailed Explanation:
Origins: Developed by the National Environmental Engineering Research Institute (NEERI), Nagpur, specifically for de-fluoridation in endemic regions of India.
Required Chemicals:
Alum (Aluminum Sulfate): This acts as a coagulant. It leads to the precipitation of fluoride ions by forming aluminum-fluoride flocs.
Lime (Calcium Hydroxide/Oxide): Lime is added to maintain the appropriate pH for optimal flocculation and to help in the settling of the sludge. It also neutralizes the acidity produced by the alum.
Bleaching Powder: A small amount is sometimes added for concurrent disinfection, but Alum and Lime are the core components.
Process Sequence: Chemical addition $\rightarrow$ Rapid mixing $\rightarrow$ Flocculation $\rightarrow$ Sedimentation $\rightarrow$ Decantation. This can be done at both the household and community levels.
Step 3: Final Answer:
The Nalgonda technique primarily relies on the interaction of Alum and Lime to precipitate fluoride out of water.
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