[Digestion] 5000 dairy cow AD system

[REX]

Hi All,

I have been approached to put together a proposal for a centralised AD using 
the manure from 5000 dairy cows. The intention is to pre-concentrate the 
dairy manure slurry and to truck the solids to a central processing unit. As 
silage and grass is extensively used as feed, we would be able to co-digest 
this with the manure to increase the gas output. Furthermore, it is intended 
to use the exhaust gas and the AD liquor to grow macro algae or a plant such 
as hyacinth (an indigenous variety that is not likely to become an invader 
should it get out) which can be shredded and added back to digestion. We aim 
to use the gas for power generation and to use the heat to keep the 
digester(s) warm.

Questions:
1. By leaving the water behind, do we lose most/all/some of the FFA? What 
impact would it have on gas production?
2. Can anyone recommend a supplier of technology for this size of plant?
3. 5000 cows is an arbitrary amount at this stage - 10 farms of 500 cows 
each. Is there a better/more economical size?

Kind regards
Rex Zietsman
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