Membrane Technologies

At Dew, we are committed for developing new technology to bring water resource to more people around the world. We have range of membrane technologies to suit your requirements.

Reverse Osmosis Systems

Reverse Osmosis (RO) employs a semi-permeable membrane that allows water molecules to pass through, while rejecting larger molecules. Water which enters the RO system is separated into two streams: pure product water (permeate) and salty water containing unwanted compounds (concentrate). The permeate is virtually free of all organics and typically contains less than ten (10%) of the dissolved minerals originally present.

Nanofiltration Systems

Nanofiltration (NF) operates essentially the same as RO except that the membrane allows more of the dissolved solids to pass through. NF membranes also operate at lower pressure than RO membranes. Applications where final water quality is not as critical, feed water pressure must be minimized, or where there is a desire to pass more minerals (as in some drinking water applications), then may be the correct technology.

Ultrafiltration Systems

Ultrafiltration (UF) is a pressure driven membrane process, with the operating pressure of the system dependendent upon the feed water temperature and filtrate flow. When compared to other membrane processes (such as reverse osmosis), UF systems require a much lower amount of pressure for operation. Typically, an ultrafiltration system will operate between 1.0 to 3 Kg/Cm2.


EDI is usually considered a water treatment technology that utilizes an electrode to ionize water molecules and separate dissolved ions (impurities) from water. It differs from other water purification technologies in that it is done without the use of chemicals and is usually a tertiary treatment to reverse osmosis (RO).