A method and apparatus for monitoring {HEAD ~ a liquid} undergoing {TAIL ~ anaerobic fermentation} in a vessel is disclosed 
undergoing
A method and apparatus for monitoring { HEAD ~ a liquid } undergoing { TAIL ~ anaerobic fermentation } in a vessel is disclosed
OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH