Semipermeable Membrane Definition

Semipermeable membrane is a thin, soft, pliable sheet of material that allows certain substances to freely pass through it while restricting the passage of other substances. In the water treatment field, a semipermeable membrane allows water to pass freely while restricts the passing of dissolved materials.

Water passes through a semipermeable membrane into a solution of higher salt concentration. This phenomenon is called Osmosis. The semi-permeable membrane is a material through which water may pass, but prohibits the traveling of nearly everything else. Because of pressurized feed water enters each pressure vessel, a portion of the incoming water goes through the semipermeable membrane. The semi-permeable membrane selectively restricts the passage of suspended and dissolved elements in the raw water.

Semipermeable membrane separating TDS and TSS 

The incoming supply water and the dissolved and suspended substances which don’t pass throughout the semipermeable membrane go to waste. One stream enters an RO system and two streams exit. The permeate is the water stream and small amount of TDS which goes through the Semipermeable Reverse Osmosis membrane. While the concentrate is the waste stream containing the water and elements which don’t go through the semipermeable membrane. The concentrate is simply concentrated incoming stream of water. The concentrate contains the TDS and the TSS that are not allowable to pass through the semipermeable membrane.

Read more about the RO Membrane.