MEMBRANE TECHNOLOGY

A membrane is a barrier of a few hundred nanometres to a few millimetres thick, which is selective and which under a transfer force will enable or inhibit the passage of certain components between two environments it separates. They are used to separate and/or concentrate particles, molecules, micro-organisms or ionic species in solution in a liquid. The advantage of these processes rests in cold operation and in their low energy and chemical product consumption.

A membrane is a barrier of a few hundred nanometres to a few millimetres thick, which is selective and which under a transfer force will enable or inhibit the passage of certain components between two environments it separates. They are used to separate and/or concentrate particles, molecules, micro-organisms or ionic species in solution in a liquid. The advantage of these processes rests in cold operation and in their low energy and chemical product consumption.


There are 4 pressure gradient membrane processes: micro-filtration (MF), ultra-filtration (UF), nano-filtration (NF) and reverse osmosis (RO). They are distinguished by the size and type of species they may separate.


Micro and ultra-filtration enable the total elimination of suspended matter to a disconnection threshold of 0.01µ. They are used essentially in surface water clarification or effluent recycling.


Nano-filtration is an intermediate process between ultra-filtration and reverse osmosis which is used to reduce divalent ions, disconnection threshold 0.001µ.


Nano-filtration is used for softening, partial desalination of brackish water or drinking water production.


Reverse osmosis is the highest-performing membrane technology. It is able to eliminate all dissolved matter. It is mainly used to desalinate sea water and produce demineralised water.