Granted Patent
Utility
US 4,396,513 · App. 06/300,145
Use of very high charge cationic polymers in biological sludge dewatering
Inventor:
David R. Haldeman
Patented Case
View Patent ↗
Granted: Aug 2, 1983
Filed: Sep 8, 1981
Inventor
David R. Haldeman
Assignee (at issue)
Betz Laboratories, Inc.
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.