Granted Patent
Utility
US 4,749,494 · App. 06/940,000
Treatment of waste water by the activated sludge process
Inventors:
Takaharu Tomoyasu, Yuzaburo Kumagai, Shiro Honda, Hikoyoshi Kanayama
Patented Case
View Patent ↗
Granted: Jun 7, 1988
Filed: Jan 20, 1987
Inventors
Takaharu Tomoyasu
Yuzaburo Kumagai
Shiro Honda
Hikoyoshi Kanayama
Assignee (at issue)
Mitsui Sekiyu Kagaku Kogyo Kabushiki Kaisha
This patent predates the USPTO's electronic file wrapper — prosecution documents from this era exist only in the Patent Office's paper records. A certified copy of the file history can be ordered from the USPTO's paper archives.