Secondary sewage treatment system
CA 2108373 C · Owner: Stuth, William L. Sr. · Inventors: Stuth, William L.
Overview
Its claims, description and drawings are in the Canadian Patents Database.
Open the CIPO recordAbstract From the Canadian patent
A secondary sewage treatment system is provided with vertically-aligned foam collecting (13), turbulent (12), mixing (11) settling (10), and sludge collecting (9) zones. A grating (7) defines the boundary between the turbulent and mixing zones. Beneath the grating (7), a buoyant media (17), such as hollow plastic spheres are , contained and occupy substantially all of the mixing zone. Air diffusers (18) including elongated draft tubes (8) extend from the turbulent zone (12) down through the mixing zone (11) for introduction of air to aerate waste water liquor and to cause the aerated liquor to recirculate up into the turbulent zone thereby creating a circulation of waste water liquor …
Read the whole patent
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 May 29, 1991 and granted September 7, 1999. A Canadian patent filed from October 1, 1989 lasts 20 years from filing, so its term ended May 29, 2011.
- A certificate of supplementary protection adds at most two years for a drug, so even that would have ended by May 29, 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.
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.