What is the active component of a reverse osmosis skid used for de-mineralized water?

The active component of a reverse osmosis skid used for de-mineralized water is the semi-permeable membrane. This membrane is crucial to the reverse osmosis process. It allows water molecules to pass through while rejecting larger molecules and ions, including salts and minerals. The driving force for this separation is typically pressure, which is applied to the water side, forcing it through the membrane and effectively removing contaminants, thus producing de-mineralized water.

The other options, while they serve important roles in water treatment systems, do not specifically characterize the main mechanism of reverse osmosis. Activated carbon filters are effective in removing organic compounds and chlorine, ion exchange resins focus on removing specific ions from water, and sand filters are primarily used for particulate removal. However, none of these components function like the semi-permeable membrane, which is specifically designed for the selective filtration needed in a reverse osmosis setup.