Method for concentrating aqueous containing solute into high concentration by hydraulic-membrane process under no difference in osmotic pressure

Abstract

The present invention relates to a method of concentrating an aqueous solution at low pressure under a zero osmotic pressure difference condition, and more particularly, to a method of concentrating an aqueous solution containing a solute to be concentrated, at low pressure under a zero osmotic pressure difference condition. The method of the present invention comprises the steps of: (a) discharging water of a solute-containing aqueous solution to be concentrated, from a reverse osmosis separator to the outside, and transferring the concentrated aqueous solution to a zero osmotic pressure difference concentrator; (b) further concentrating the concentrated aqueous solution using the zero osmotic pressure difference concentrator comprising a feed chamber and a draw chamber, which are separated from each other by a reverse osmosis membrane or a forward osmosis membrane; and (c) recovering the solute and water from the aqueous solution further concentrated in the zero osmotic pressure difference concentrator. When the method of concentrating the aqueous solution at low pressure under the zero osmotic pressure difference condition is used, the aqueous solution can be concentrated to the maximum saturation concentration of a solute or a solution concentration of 100% using a reduced amount of energy without having to use an extraction solvent. In addition, there is an advantage in that a separate osmosis draw solution does not need to be used.