Secondary sewage treatment system
CA 2238729 C · Owner: Stuth, William L. · 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 a treatment vessel 7 disposed within a septic tank. The treatment vessel has a draft tube 9 for aerating and circulating waste liquor through the treatment vessel and through media contained within the treatment vessel. The media has one part 20 that is submerged media and another part 22 that is an unsubmerged trickle media. The operation of the draft tube circulates waste liquor within the treatment vessel through the submerged media and up through the draft tube where it is expelled and trickles down through the trickle media back into the liquor in the lower portion of the treatment vessel.
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 November 12, 1996 and granted August 20, 2002. A Canadian patent filed from October 1, 1989 lasts 20 years from filing, so its term ended November 12, 2016.
- A certificate of supplementary protection adds at most two years for a drug, so even that would have ended by November 12, 2018.
- 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.