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Expired Canadian patentCanada

Method of controlling an anaerobic treatment process

CA 1236596 A · Owner: Purac Aktiebolag · Inventors: Welander, Thomas; Annergren, Goran; Hansson, Goran

CIPO record

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Abstract From the Canadian patent

The invention relates to a method of controlling a hydrolysis step in an anaerobic treatment process for treating wastewater from the manufacture of peroxide bleached mechanical or chemi-mechanical pulp. The method involves continuously measuring the redox potential of outgoing water from the hydrolysis step and controlling the ingoing water to the hydrolysis step at demand, so that some ingoing water is directed past the hydrolysis step to a subsequent aerobic step. The method ensures that anaerobic bacteria in a methane fermentation step which is subsequent to the hydrolysis step is not killed by hydroperoxide in the wastewater emanating from the hydrolysis step, the hydroperoxide being …

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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

  • Granted May 10, 1988. A Canadian patent filed before October 1, 1989 lasted 17 years from grant, so its term ended May 10, 2005.
  • We check Canadian rights only. A patent in its family in another country could still be in force: check its family on Google Patents.
FiledAugust 9, 1984
GrantedMay 10, 1988
Term endedMay 10, 2005
Patent numberCA 1236596 A
Classification (IPC)C02F3/30 +2 more

Timeline

Timeline From CIPO dates

1985198819911994199720002003Application filedAug 9, 1984Patent grantedMay 10, 1988Term endedMay 10, 2005

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