Granted Patent
Utility
US 5,651,889 · App. 08/621,237
Sludge treatment membrane apparatus
Inventors:
Sakae Wataya, Kimio Yamamoto, Hirokazu Shirage, Kouji Irie, Tadaaki Hashimoto
Patented Case
View Patent ↗
Granted: Jul 29, 1997
Filed: Mar 25, 1996
Inventors
Sakae Wataya
Kimio Yamamoto
Hirokazu Shirage
Kouji Irie
Tadaaki Hashimoto
Assignee (at issue)
Mitsui Petrochemical Industries, Ltd.
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.