High salinity water purification processes and systems

Abstract

A high salinity water purification system and process, including a forward osmosis system and a reverse osmosis or nanofiltration system. A concentrated brine of a zinc or iron complex combined with a salt or acid draws pure water across the FO membrane from the influent water. The diluted brine is pumped through a vessel holding an anionic adsorption media to remove the zinc or iron complex and the resultant brine is passed through the RO or nanofiltration system to obtain purified water and a concentrated brine stream. The adsorption media is regenerated by a rinse cycle using fresh water or water from the RO system, removing the zinc or iron complex adhered to the media. The resultant brine is stored and mixed with the output of the RO system.

What is claimed is: 
     
         1 . A system for purifying high salinity influent fluids, comprising:
 a forward osmosis (FO) system comprising an FO membrane, an influent side input port and an influent side output port arranged on an influent side of the FO membrane, and an FO output side input port and an FO output side output port arranged on an output side of the FO membrane;   one or more vessels holding an anionic base adsorption media for removing zinc or iron complex from a brine;   a reverse osmosis (RO) or nanofiltration system;   the FO system configured to receive the influent fluid at the influent side input port and to pass concentrated fluid out the influent side output port;   the RO or nanofiltration system configured to receive input fluid at an input port and to pass concentrated fluid which did not pass through a membrane of the RO or through the nanofiltration system at an output port, and purified fluid which has passed through the RO membrane or nanofiltration system;   a recirculating brine flow path;   a concentrated brine draw containing zinc or iron complex and another salt brine or acid pumped into the FO output side input port, the concentrated brine draw having a level of total dissolved solids (TDS) higher than the TDS level in the influent fluid;   a pump for pumping the concentrated brine draw through the FO system from the FO output side input port to the FO output side output port, wherein pure water is drawn through the FO membrane to dilute the concentrated brine draw; the recirculating brine flow path passing from the FO output side output port to the one or more vessels to remove the zinc or iron complex from the diluted concentrated brine and to the RO or nanofiltration system and then to the FO output side input port, the diluted concentrated brine is in a multivalent form, allowing the anionic adsorption media to have a strong natural attraction to it; and   a rinse system for rinsing the adsorption media with an elutant containing water in a rinse cycle to remove the zinc or iron complex to form a resultant brine with zinc or iron complex, and then combining the resultant brine with the RO stream of concentrated brine draw to reconstitute a concentrated brine draw passed into the recirculating brine flow path to the FO output side input port.   
     
     
         2 . The system of  claim 1 , wherein the rinse system comprises:
 a brine storage tank in fluid communication with the one or more vessels;   an elutant source;   a valve system for passing elutant into one of the one or more vessels from the elutant source to rinse the adsorption media to remove the zinc or iron complex from the anionic adsorption media;   a brine storage tank for storing brine from the rinsing including the zinc or iron complex;   a mixer for mixing the stored brine with the concentrated fluid from the RO or nanofiltration system to pass into the brine recirculation path.   
     
     
         3 . The system of  claim 2 , further comprising a cooling heat exchanger in the recirculating brine flow path downstream of the brink tank for cooling the brine draw prior to entering the FO membrane to reduce mineral fouling on the FO membrane. 
     
     
         4 . The system of  claim 2 , further comprising:
 a sensor for measuring the pH of the reconstituted brine draw;   an acid feed tank for storing an acid;   a pump for introducing acid from the tank into the reconstituted brine draw to control the pH of the reconstituted brine draw to approximately 2.5 to 5.0.   
     
     
         5 . The system of  claim 1 , wherein the elutant is fresh water. 
     
     
         6 . The system of  claim 1 , wherein the elutant is purified water from the RO or nanofiltration system. 
     
     
         7 . The system of  claim 1 , wherein said one or more vessels comprises a plurality of vessels, and wherein one vessel is operational for passing the diluted brine draw over the anionic adsorption media while at least another of the plurality of vessels is in a rinse cycle or in a standby, ready-for-use condition. 
     
     
         8 . The system of  claim 1 , further comprising:
 a capacitive deionization system for processing the resultant brine to form a capacitive deionization permeate and a capacitive deionization concentrate;   the capacitive deionization permeate combined with the diluted brine draw prior to passing the diluted brine draw over the anionic adsorption media;   the capacitive deionization concentrate passed into a brine storage tank for combination with the concentrated brine draw.   
     
     
         9 . The system of  claim 1 , further comprising:
 an elutant tank holding the elutant; a caustic tank for holding a caustic;   a sensor for measuring the pH of the elutant stored in the elutant tank;   and a pump for introducing sufficient caustic from the caustic tank into the elutant tank to maintain the pH of the elutant in a range of  9  to  12 .   
     
     
         10 . The system of  claim 1 , wherein:
 the influent fluid has levels of TDS in the range of 30,000 to 150,000 ppm; and   the concentrated brine draw has levels of TDS in the range of 250,000 to 500,000 ppm.   
     
     
         11 . The system of  claim 1 , wherein the concentrated brine draw includes one or more of zinc chloride, zinc bromide, sodium chloride and magnesium chloride. 
     
     
         12 . The system of  claim 1 , wherein the acid comprises one of hydrochloric acid, sulfuric acid, phosphoric acid, muriatic acid, citric acid, sulfamic acid, carbonic acid and nitric acid.