Granted Patent
Utility
US 5,132,021 · App. 07/689,367
In situ treatment of waste water to prevent ground water contamination
Inventor:
William Alexander
Patented Case
View Patent ↗
Granted: Jul 21, 1992
Filed: Apr 22, 1991
Inventor
William Alexander
Assignee (at issue)
American Colloid Company
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.