Sounds nice but with all systems where matter is going around in cycles one should try to check the losses and environmental effects. In systems involving digestion and recycling to agriculture it is especially the losses of methane, ammonia and nitrous oxide to air and the losses of nitrate to water. This has nothing to do with the recycling theory but instead with how you build and manage the system. Energy efficiency is also interesting as the raw material e g manure and agricultural residues although renewable still might become a limited resource. So how to tune and optimize the system and not only the digestion plant. Something to think about. Bjorn Dahlroth
-----Ursprungligt meddelande----- Från: [email protected] [mailto:[email protected]] För [email protected] Skickat: den 19 november 2010 03:44 Till: [email protected]; For Discussion of Anaerobic Digestion Ämne: [Digestion] R.R.R. ->was-> Re Digestate as fertilizer > As a result some people see AD as "biogas", some as "Carbon", some as > "waste disposal", some as "pathogen reduction" and some as "fertiliser". > What we really need to do is see anaerobic digestion as all of the above > and as part of a larger system. This involves a move away from the typical > Western "linear" approach (of extract, use, discard) to a more cyclic > approach (we have a Reuse, Recycle, Reduce slogan going around, sometimes > with a 4th R that I can't remember). I know some areas have been doing > this for centuries, and even Westerners used to be better at it (before > coal and oil!). > Okay... since we're on a roll here, tell me if you think a scenario similar to the following sounds TOO FAR OUT: animal manure goes into an in-ground plug/flow digester; spent digestate goes to both sediment pond and aerobic compost pile; sediment pond produces duckweed and nutrient for hydroponic grow beds; duckweed is harvested and dried for animal feed; methane produced runs an engine; engine coolant keeps digester warm (radiator coils wrap around digester); engine runs generator to produce electricity; electricity lights and runs pumps for hydro .... what have I forgotten? _______________________________________________ Digestion mailing list to Send a Message to the list, use the email address [email protected] to UNSUBSCRIBE or Change your List Settings use the web page http://lists.bioenergylists.org/mailman/listinfo/digestion_lists.bioenergyli sts.org for more information about digestion, see Beginner's Guide to Biogas http://www.adelaide.edu.au/biogas/ and the Biogas Wiki http://biogas.wikispaces.com/ _______________________________________________ Digestion mailing list to Send a Message to the list, use the email address [email protected] to UNSUBSCRIBE or Change your List Settings use the web page http://lists.bioenergylists.org/mailman/listinfo/digestion_lists.bioenergylists.org for more information about digestion, see Beginner's Guide to Biogas http://www.adelaide.edu.au/biogas/ and the Biogas Wiki http://biogas.wikispaces.com/
