Patents by Inventor Pek L. Choo

Pek L. Choo has filed for patents to protect the following inventions. This listing includes patent applications that are pending as well as patents that have already been granted by the United States Patent and Trademark Office (USPTO).

  • Colloidal silica/polyelectrolyte blends for natural water clarification
    Patent number: 5620629
    Abstract: This invention relates to a composition of matter of a silica sol/water soluble cationic polymer mixture. The colloidal silica may also be conditioned by passing over a cationic exchange resin prior to addition of cationic polymer.
    Type: Grant
    Filed: November 26, 1995
    Date of Patent: April 15, 1997
    Assignee: Nalco Chemical Company
    Inventors: Kristine S. Salmen, Pek L. Choo, David A. Picco, Michio Kobayashi
  • Sulfide ion-selective electrodes for control of chemical feed of organic sulfide products for metal ion precipitation from waste water
    Patent number: 5401420
    Abstract: A wastewater treatment system and method for chemical precipitation and removal of metals from wastewater in a continuous or batch treatment process includes an ion-selective sulfide electrode and a reference electrode disposed in a precipitation tank for measuring an electrochemical potential therebetween in a predetermined range. A controller unit is provided which is responsive to the electrochemical potential in the predetermined range and is connected to a precipitant feed unit for automatically controlling the chemical precipitant fed into the precipitation tank.
    Type: Grant
    Filed: March 23, 1994
    Date of Patent: March 28, 1995
    Assignee: Nalco Chemical Company
    Inventors: Kristine S. Siefert, Pek L. Choo, Wayne M. Carlson
  • Method for removing metals from a fluid stream
    Patent number: 5346627
    Abstract: A method is provided for removing metals from a fluid stream containing these metals. The method involves treating the fluid stream with a water soluble ethylene dichloride ammonia polymer having a molecular weight of from 500 to 100,000 that contains at least 5 mole percent of dithiocarbamate salt groups to form a complex with the metals. Then, the fluid stream is passed through a filtering device to remove the complexes from the fluid stream.
    Type: Grant
    Filed: September 20, 1993
    Date of Patent: September 13, 1994
    Assignee: Nalco Chemical Company
    Inventors: Kristine S. Siefert, Pek L. Choo, John W. Sparapany, John H. Collins
  • System using sulfide ion-selective electrodes for control of chemical feed of organic sulfide products for metal ion precipitation from waste water
    Patent number: 5328599
    Abstract: A wastewater treatment system and method for chemical precipitation and removal of metals from wastewater in a continuous or batch treatment process includes an ion-selective sulfide electrode and a reference electrode disposed in a precipitation tank for measuring an electrochemical potential therebetween in a predetermined range. A controller unit is provided which is responsive to the electrochemical potential in the predetermined range and is connected to a precipitant feed unit for automatically controlling the chemical precipitant fed into the precipitation tank.
    Type: Grant
    Filed: March 8, 1993
    Date of Patent: July 12, 1994
    Assignee: Nalco Chemical Company
    Inventors: Kristine S. Siefert, Pek L. Choo, Wayne M. Carlson