Hello all  and Steven Bolgiano
I couldn't resist giving my input.

I have been experimenting with digesting grass and foodscraps in bags and I wonder if you will encounter something similar to me.  The upper surface of the 'contents' tended to dry out and harden into bigger chunks. No particular problem as I could 'manipulate'  the mass  by pushing on the outside of the bag. Large  volumes  might be more of a problem, as in your case.

As Paul Harris  suggested a prototype will show up any unforeseen problems, eg solids settling, ammonium build up or engineering issues like getting the stuff in and out etc. Later, you could use the digestate as starter.

I got a bit confused by your reference to the water table, however  in my case, rain water in the ground underneath the digester robs heat. I believe you have identified the threat but (for others) make sure the the digester footprint stays free of ground water and is insulated well. I didn't quite have a handle on it.

kia ora
Stephen Rodda
NZ


Our plan is as follows:
1) Run digestion process as a batch process, loading one time ...........snipped   and below
2) Use "bladder bag" containments ...
3) Each Bladder Bag is set into a shallow excavation with only 6 inches of bag above ground surface. Each bag system is covered with low profile "greenhouse" providing passive heat.

Some of the limiting factors of our region:
1) We have a very low water table, so in ground constructions with concrete are problematic.
2) Federal limitations for lands determined to fall under "wetlands" regulations cover most of our peninsula
3) Small to medium sized poultry farm's financial resources and method of operation are not compatible with existing commercial systems.


Cheers,
Steven

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