The technique for removing fluoride from water by using lime and alum is called

Appeared in: UPPSC 2022

Explanation

The Nalgonda technique is a specific water treatment process designed for defluoridation.
It uniquely uses a combination of alum (a coagulant) and lime (for pH adjustment and precipitation) to remove fluoride.
The process involves coagulation, flocculation, and sedimentation, where fluoride binds to aluminum hydroxide flocs and settles down.
It was developed by India's National Environmental Engineering Research Institute (NEERI) as a cost-effective method for community water supplies.

Option A: Sedimentation is a general physical process where suspended solids settle by gravity. It is a step within the Nalgonda technique but not the specific technique itself for chemical removal of dissolved fluoride.
Option B: The ion exchange technique uses specialized synthetic resins to swap fluoride ions with other ions (like chloride). It does not use lime and alum.
Option D: SODIS (Solar Water Disinfection) is a method that uses solar UV radiation and heat to kill pathogenic microorganisms (bacteria, viruses). It does not remove chemical contaminants like fluoride.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Water purification methods, specifically defluoridation as background academic context rather than a clinical decision trigger.
Understanding defluoridation is crucial for community health nurses, especially in areas with endemic fluorosis, to advise communities on safe drinking water practices.
Nurses play a key role in identifying signs of dental and skeletal fluorosis during health screenings and educating families about the importance of using treated water.
Patient safety depends on ensuring drinking water has fluoride levels within the safe limit (below 1.5 mg/L) to prevent the irreversible effects of fluorosis.

How to Approach the Question

This is a factual recall question that tests knowledge of specific public health engineering techniques.
First, identify the key components mentioned in the question stem: 'removing fluoride', 'lime', and 'alum'.
Next, evaluate each option based on these keywords.
Recall or deduce the function of each technique. 'Sedimentation' is a general process. 'Ion exchange' uses resins. 'SODIS' uses sunlight for disinfection.
The 'Nalgonda technique' is specifically known for using lime and alum for defluoridation.
Therefore, match the specific chemicals (lime and alum) and the purpose (fluoride removal) to the correct named technique.

Concept Tested & Keywords

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