Vacuum enhanced direct contact membrane distillation

Abstract

The present disclosure provides methods and systems for purifying an impaired liquid. In a particular example, the disclosure provides methods and systems for purifying water containing a solute. A feed stream of solute containing water is introduced in a flow chamber. A permeate stream of water at least substantially free of the solute is placed in the flow chamber. A hydrophobic membrane is placed between the feed stream and the permeate stream. A vacuum is applied to the permeate stream. A vapor pressure differential causes water to vaporize from the feed stream, pass through the hydrophobic membrane, and condense in the permeate stream.

1 - 14 . (canceled) 
   
   
       15 . A method for extracting fresh water from an impaired water source, the method comprising:
 supplying impaired water in a feed stream;   supplying a permeate stream adjacent to the feed stream;   positioning a membrane between the feed stream and the permeate stream; and   applying a vacuum to the permeate stream;   whereby a vapor pressure differential across the membrane causes water to evaporate from the solution in the feed stream, pass through the membrane, and condense in the permeate stream.   
   
   
       16 . The method of  claim 15 , wherein the temperature of the feed stream is higher than the temperature of the permeate stream. 
   
   
       17 . The method of  claim 15 , wherein the impaired water comprises sodium chloride. 
   
   
       18 . The method of  claim 15 , wherein the impaired water comprises sea salt. 
   
   
       19 . The method of  claim 15 , wherein the permeate stream is distilled deionized water. 
   
   
       20 . The method of  claim 15 , wherein the permeate stream and feed stream each have a flow velocity and the flow velocity of the permeate stream is at least approximately equal to the flow velocity of the feed stream. 
   
   
       21 . The method of  claim 15 , wherein the feed stream is supplied in a direction countercurrent to the permeate stream. 
   
   
       22 . The method of  claim 15 , wherein the membrane is hydrophobic. 
   
   
       23 . The method of  claim 22 , wherein the hydrophobic membrane is microporous. 
   
   
       24 . The method of  claim 22 , wherein the hydrophobic membrane is a composite membrane comprising a polytetrafluoroethylene active layer and a polypropylene support sublayer. 
   
   
       25 . The method of  claim 22 , wherein the hydrophobic membrane is a symmetric, isotropic, polypropylene membrane. stream. 
   
   
       26 . The method of  claim 15 , further comprising applying a vacuum to the feed stream. 
   
   
       27 - 32 . (canceled)