The bio-assimilation tank (empty)
The Strogg Bio-Assimilation Tank is a Strogg machine that appears in the Processing Plant within the Industrial region of the Stroggos capital city of Cerberon.
The machine seems to produce (or at least deploy) a series of Light Guards from a small tank. While the exact nature and method of operation of the device remain unknown, it's conceivable that a basic form of Stroggification - compared to the more advanced processes seen in Quake 4 - is occurring in the Processing Plant.
This is the second machine that Bitterman has to shut down in order to render ther factory inoperable. Incidentally, the player can rush to the control panel to shut the machine down before all of the Light Guards are deployed, but this won't stop them being deployed anyway.