Reverse Osmosis

Desalination is the removal of dissolved salts from a solution. This can be achieved in a number of ways, with the most common forms falling into three main categories - membrane, chemical or thermal processes.

Reverse Osmosis (RO) is a process that uses a pump and a semi-permeable membrane to cause the separation of dissolved salts from a liquid. The pump provides the driving force to the membrane that is greater than the osmotic pressure of the liquid. The semi-permeable membrane allows water and some ions to pass, but retains most of the dissolved salts. The reverse osmosis membrane also removes more than 98% of residual biological and colloidal matter from the feed water, resulting in a highly purified product stream.

Osmosis is the natural process which occurs when water spontaneously flows from a purer solution, through a semi-permeable membrane into a more concentrated solution. Osmotic pressure is the pressure associated with osmosis.

Reverse Osmosis is used for desalting sea water (SWRO) and brackish water (BWRO).

High Recovery

High recovery designs allow for 90% or more of the intake water to be utilised, minimising disposal of the RO concentrate. To achieve high water recovery pre-treament is designed to enhance membrane recovery, supported by two-pass RO process. Feed water temperature also effect the efficiency of membranes.