(19)  United States  (12)  Patent Application Publication  MUKHOPADHYAY  (10)  Pub. No.: US 2002/0153319 Al  ( 43)  Pub. Date:  Oct. 24, 2002  (54)  METHOD AND APPARATUS FOR HIGH  EFFICIENCY REVERSE OSMOSIS  OPERATION  (76)  Inventor:  DEBASISH MUKHOPADHYAY,  PALO ALTO, CA (US)  ( *)  Notice:  This is a publication of a continued pros- ecution application (CPA) filed under 37  CFR 1.53(d).  (21)  Appl. No.:  09/243,237  (22)  Filed:  Feb. 2, 1999  (62)  Division of application No. 08/909,861, filed on Aug.  12, 1997, now patented.  (51)  Int. Cl.7  .....................................................  BOID 61/00  (52)  U.S. Cl.  ............................................  210/652;  210/638  US  20020153319Al  Correspondence Address:  R REAMS GOODLOE JR  10725 SE 256TH STREET  SUITE 3  KENT, WA 980316426  Unique ultrapure water produced by reverse osmosis equip› ment. The high purity or ultrapure water is characterized by  extremely low levels of Total Organic Carbon that are  achieved after a single pass reverse osmosis process step.  The feedwater to the reverse osmosis process is preferably  pretreated to remove hardness and non-hydroxide alkalinity  by simultaneous removal in a weak acid cation exchange  resin. The process includes ionization of sparingly ionizable  components, such as silica, by adjusting the pH up to about  10.5 or higher. The passage of boron, silica, and TOC is  therefore significantly reduced. Consequently, the high  purity water is produced with high recovery rates from the  entering feedwater. Therefore, a unique ultrapure water  product is provided that significantly reduces costs for  post-treatment in downstream polishing steps.  Related U.S. Application Data  Publication Classification  (57)  ABSTRACT  10  RAW  WATER  Ca(OH)2  ..[47  r------------ ------------,  I  I  I  I  I  I  I  I  I  I  I  I  I  I  I  I  48  MEMBRANE  32  49  u  REJECT  V 