What does the RO (reverse osmosis) process primarily remove from water?

The reverse osmosis (RO) process is primarily designed to remove a wide range of contaminants from water, with a key focus on salts and other dissolved substances. This technique utilizes a semi-permeable membrane that allows water molecules to pass through while blocking larger molecules and ions, including salts, heavy metals, and some organic compounds.

The efficiency of reverse osmosis lies in its ability to reduce total dissolved solids (TDS) significantly, making it an essential process in water purification systems, particularly in hemodialysis. Ensuring that the water used for dialysis has low concentrations of salts and contaminants is crucial for patient safety and treatment efficacy.

While RO does help in reducing microorganisms and larger particles, it is specifically optimized for the removal of salts and dissolved contaminants, which is why this option is the most accurate response.