What process does reverse osmosis rely on to remove contaminants from water?

Reverse osmosis operates primarily through the application of pressure to push water through a semipermeable membrane. This membrane is designed to allow water molecules to pass while blocking a significant amount of dissolved salts, bacteria, and other contaminants. The process relies on the natural osmotic pressure in a solution, which is countered by the applied pressure, allowing pure water to move from an area of higher solute concentration to an area of lower solute concentration. This pressure-driven process results in the effective removal of impurities, making reverse osmosis a widely utilized method for water purification, especially in applications such as desalination and wastewater treatment.

In contrast, processes like ultrafiltration and mechanical filtration utilize different mechanisms that do not involve the direct application of pressure in the same way, and the application of heat is typically associated with distillation rather than reverse osmosis.