Patent ID: 7914680
Filing Date: 2011-03-29
Classification: B01D,C02F,Y02A

Abstract:
1. A water purification method comprising: passing a stream of feed water and a stream of draw solution through a first forward-osmosis unit to produce a diluted stream of draw solution; passing the diluted stream of draw solution through a desalination unit to produce a stream of product water and a stream of concentrated draw solution; whereby desalinating the diluted stream of draw solution requires less energy than desalinating the draw solution; wherein passing the diluted stream of draw solution through a desalination unit to produce a stream of product water and a stream of concentrated draw solution comprises passing a first osmotic draw solution comprising a first relatively easily extractable osmotic agent through the desalination unit to cause water from the diluted stream of draw solution to dilute the first osmotic draw solution comprising a first relatively easily extractable osmotic agent to form a diluted first osmotic draw solution.