Issued Patents 1989
Showing 1–2 of 2 patents
| Patent # | Title | Co-Inventors | Date |
|---|---|---|---|
| 4859341 | Method for controlling aerating units in a wastewater treatment process | — | 1989-08-22 |
| 4818446 | Apparatus for introducing a gas into a fluid | Erhard Schreiber | 1989-04-04 |