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Expired Canadian patentCanada

Sludge transfer systems and methods

CA 2038523 C · Owner: Zuback, Joseph E. · Inventors: Zuback, Joseph E.

CIPO record

Overview

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Its claims, description and drawings are in the Canadian Patents Database.

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Abstract From the Canadian patent

Known water or wastewater treatment methods wherein a layer of, fluid sludge is formed during operation of the method in a first chamber beneath a body of liquid partially filling the first chamber to an upper liquid level, fluid sludge from the first chamber is processed in a second chamber and a stream of fluid sludge is conveyed by a conduit from the first chamber as influent to the second chamber, are improved by creating upward flow of fluid sludge through a vertical stackpipe by introducing large bubbles within the stackpipe with its inlet end immersed in the layer of fluid sludge discharging, fluid sludge through an elongated longitudinal side opening in the top portion of the …

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Listed from its CIPO record in Patent Yard's archive of Canadian patents past their term. Its claims, description and drawings are in the CIPO record and on Google Patents, and the Claude kit works from them.

Why it's free to use

  • Filed March 18, 1991 and granted August 18, 1998. A Canadian patent filed from October 1, 1989 lasts 20 years from filing, so its term ended March 18, 2011.
  • A certificate of supplementary protection adds at most two years for a drug, so even that would have ended by March 18, 2013.
  • We check Canadian rights only. A patent in its family in another country could still be in force: check its family on Google Patents.
FiledMarch 18, 1991
GrantedAugust 18, 1998
Term endedMarch 18, 2011
Patent numberCA 2038523 C
Classification (IPC)C02F11/00 +2 more

Timeline

Timeline From CIPO dates

1992199419961998200020022004200620082010Application filedMarch 18, 1991Patent grantedAug 18, 1998Term endedMarch 18, 2011

Sources & verification

Everything on this page comes from the CIPO record linked above. Contains information licensed under the Open Government Licence – Canada.