Method of cleaning membranes

Abstract

The present invention relates a method for cleaning polymeric microfiltration membranes and membrane units, and to compositions useful in such methods. The compositions include at least one soluble sulfite reducing agent and a compatible solvent.

1 - 36 . (canceled) 
     
     
         37 . A method of cleaning a microfiltration or ultrafiltration porous polymeric membrane contaminated with a contaminant, comprising:
 providing a cleaning solution prepared from at least two sulfites and a solvent; and   contacting the contaminated microfiltration or ultrafiltration porous polymeric membrane with the cleaning solution.   
     
     
         38 . The method according to  claim 37 , wherein the cleaning solution further comprises an enhancing agent. 
     
     
         39 . The method according to  claim 38 , wherein the enhancing agent is selected from the group consisting of inorganic acids, organic acids, and mixtures thereof. 
     
     
         40 . The method according to  claim 39 , wherein the enhancing agent comprises citric acid. 
     
     
         41 . The method according to  claim 37 , wherein the sulfites are selected from the group consisting of sodium metabisulfite, sodium hydrosulfite, sodium sulfite, potassium metabisulfite, potassium hydrosulfite, potassium sulfite, and mixtures thereof. 
     
     
         42 . The method according to  claim 41 , wherein the solvent comprises water and the sulfites comprise sodium metabisulfite and sodium hydrosulfite. 
     
     
         43 . A method of treating water, comprising:
 providing a water treatment system comprising a microfiltration or ultrafiltration membrane;   connecting a source of water to be treated to the water treatment system;   filtering the water through the membrane, thereby retaining a contaminant on a surface of the membrane;   providing a cleaning solution prepared from at least two sulfites and a solvent; and   contacting the contaminated membrane with the cleaning solution.   
     
     
         44 . The method of  claim 43 , further comprising the step of adding a flocculating agent to the water. 
     
     
         45 . The method of  claim 43 , further comprising the step of isolating the membrane from the source of water to be treated. 
     
     
         46 . The method of  claim 45 , further comprising the step of reconnecting the membrane to the source of water to be treated. 
     
     
         47 . The method of  claim 43 , wherein the at least two sulfites are selected from the group consisting of sodium metabisulfite, sodium hydrosulfite, sodium sulfite, potassium metabisulfite, potassium hydrosulfite, and potassium sulfite. 
     
     
         48 . A method of cleaning a microfiltration or ultrafiltration membrane, comprising the step of:
 cleaning the microfiltration or ultrafiltration membrane using a composition comprising at least two sulfites.   
     
     
         49 . The method of  claim 48 , wherein the at least two sulfites are selected from the group consisting of sodium metabisulfite, sodium hydrosulfite, sodium sulfite, potassium metabisulfite, potassium hydrosulfite, and potassium sulfite. 
     
     
         50 . The method of  claim 49 , wherein the composition comprises sodium metabisulfite and sodium hydrosulfite. 
     
     
         51 . The method of  claim 48 , wherein the composition further comprises an enhancing agent.