The GATE Grind

GATE 2022 CE (CE1) – Question 27

Water and Waste Water Quality and Treatment · Unit processes and operations · 1 mark · Multiple select

Which of the following process(es) can be used for conversion of salt water into fresh water?

  1. Microfiltration
  2. Electrodialysis
  3. Ultrafiltration
  4. Reverse osmosis

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Correct answer: (B) Electrodialysis; (D) Reverse osmosis

Explanation

Desalination requires removing dissolved ions. **Electrodialysis** moves ions through selective membranes under an electric field; **reverse osmosis** retains salts while allowing water through a dense membrane.

Microfiltration and ultrafiltration mainly remove particles and macromolecules; their pores do not reject dissolved salts sufficiently. **Answer: B and D**.