Method for treating waste water sludge
CA 2208970 C · Owner: Kemira Oyj · Inventors: Jokinen, Simo
Overview
Its claims, description and drawings are in the Canadian Patents Database.
Open the CIPO recordAbstract From the Canadian patent
The invention relates to a method for treating waste water sludge comprising at least one metal originating from a waste water treatment coagulant and , phosphorus and heavy metals in order to recover said at least one metal and phosphorus and to discharge said heavy metals. In this method said waste water sludge is acidified to dissolve metals contained in the sludge thereby yielding an acidified sludge solution containing at least 1 % by weight of at least one metal to be recovered. In a first precipitation stage the pH of said acidified sludge solution is raised to precipitate at least one metal to be recovered as a phosphate, and thereafter the phosphate precipitate is …
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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 December 29, 1995 and granted May 21, 2002. A Canadian patent filed from October 1, 1989 lasts 20 years from filing, so its term ended December 29, 2015.
- A certificate of supplementary protection adds at most two years for a drug, so even that would have ended by December 29, 2017.
- We check Canadian rights only. A patent in its family in another country could still be in force: check its family on Google Patents.
Timeline
Timeline From CIPO dates
Sources & verification
Official CIPO records
Everything on this page comes from the CIPO record linked above. Contains information licensed under the Open Government Licence – Canada.