Which filtration method removes dissolved ions and requires pressure to pass water through a semi-permeable membrane?

• A. Reverse Osmosis
• B. Media Filter
• C. Disc Filter
• D. Screen Filter

Answer: (A)

The main idea is membrane-based filtration that can remove dissolved ions, which requires applying pressure to push water through a semi-permeable membrane. Reverse osmosis uses a special membrane that blocks most dissolved salts and ions, so when water is forced through under pressure, the purified water passes while ions are left behind. This is why it’s used for desalination and removing minerals or contaminants that aren’t visible as particles.

Other options rely on trapping particles by size or media, not on rejecting dissolved ions with a membrane. They filter out suspended solids and turbidity but don’t remove dissolved salts or minerals in the same way, so they aren’t effective for dissolvable ions.