What are exactly the jobs of the outlet pipe, the displacement tanks, and the loose cover in the anaerobic digester? I pointed to them using the red color.

http://www9.0zz0.com/2016/12/10/16/748494966.jpg

 

Given that the displacement tank level is above the main tank it probably acts as a safety regulator for the pressure inside and should the gas outlet pipe be turned off or blocked the build up of gas will push the slurry level down and allow the gas to escape through the outlet pipe and lift the loose cover.slightly to escape; kind of a crude one-way valve.

Edited December 10, 20169 yr by StringJunky

Given that the displacement tank level is above the main tank it probably acts as a safety regulator for the pressure inside and should the gas outlet pipe be turned off or blocked the build up of gas will push the slurry level down and allow the gas to escape through the outlet pipe and lift the loose cover.slightly to escape; kind of a crude one-way valve.

Thank you for your help but i'm sorry, my original language isn't English and i can't understand you. Could you say that again in a more simple way, please?