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# (19) United States 

# (12) Patent Application Publication MUKHOPADHYAY 

# (54) METHOD AND APPARATUS FOR HIGH EFFICIENCY REVERSE OSMOSIS OPERATION 

(76) Inventor: DEBASISH MUKHOPADHYAY, PALO ALTO, CA (US) 

Correspondence Address: R REAMS GOODLOE JR 10725 SE 256TH STREET SUITE 3 KENT, WA 980316426 

( *) 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. 

## Related U.S. Application Data 

<img src='content_image/927778.jpg'>

US 20020153319Al 

# (10) Pub. No.: US 2002/0153319 Al 

# ( 43) Pub. Date: Oct. 24, 2002 

(51) Int. Cl.7 ..................................................... BOID 61/00 

(52) U.S. Cl. ............................................ 210/652; 210/638 

## (57) ABSTRACT 

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. 

## Publication Classification 

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