Anaerobic digester accident

[chemEIT]

hi,
I am trying to get some info on AD accidents - most references I see talkabout the possibility of explosion, but I haven't heard of specific instances and I'm trying to get a handle on whether they are rare, extremely rare, never happen or happen more often than you'd think but
aren't widely publicized. During startup/shutdown it might be built up an explosive mixture if methane production starts early (thus CO2 cannot replace the air or oxygen is not consumed before).

 

[dirkbouma]

The real danger has to do with confined spaces. Aerobic digestion takes place 9x faster than anaerobic, and will use up the oxygen well in advance of significant methane production. Putting personnel in a confined space without oxygen would be a more significant hazard.