Wayne<div><br></div><div>I did some work on dry digestion about ten years ago while working in academia. The concept was essentially an anaerobic compost heap, a fixed bed, without irrigation.</div><div><br></div><div>So the "plant" would be very simple - one would operate several fixed-bed digesters in sequence to ensure a steady biogas output. It <i>might</i> be slower than conventional digestion - that's an unknown, as yet - but that's not a big deal if the plant is cheap.</div>
<div><br></div><div>It had its origins in studies of biogas generation in landfills. Conventional models of the process assume the solids are more-or-less inert, with all reaction taking place in the liquid phase. </div>
<div><br></div><div>I think that model is incomplete and that it is possible for the main reaction zone to lie <i>within</i> the solids. A reaction front develops, with distinct acidogenic and methanogenic zones, which advance through the solids, just as dry rot advances through wood. As I envisage the mechanism, it would be <b>very</b> stable once started - whether mesophilic or thermophilic. The tricky bit is getting it started - but I think that's easy once the principle is understood. </div>
<div><br></div><div>This reaction front idea was taken seriously by the research community, so about a dozen papers were accepted for publication in research journals on various aspects of it between about 1998 and 2005. However, I never managed to get funding for experimental verification, so it remains unproven. I'm semi-retired now - so the conventional research route to proof is closed. However, one of these days I mean to turn my garden shed into a laboratory and have a go - when I get time.</div>
<div><br></div><div>Don't confuse this concept with the kind of fixed-bed digester in which the leachate is recycled to irrigate the bed. That works well enough - but the plant is more complex and costly - and reaction takes place in the liquid phase. </div>
<div><br></div><div>Thanks to a computer crash a few years ago, I no longer have soft copy of any of my papers. However, I could send hard copies by post, And if you'd like to have a go at applying my ideas, I'd be happy to advise. </div>
<div><div><br></div><div>Finally, my sympathies on the harsh winter you guys are having. Here in Ireland, we have had no real winter - yet - so I still have a few summer flowers in bloom in my garden!</div><div><br></div>
<div>Duncan Martin</div><div>Cloughjordan Ecovillage, County Tipperary, Ireland</div><div><br><br><div class="gmail_quote">On 12 February 2012 20:15, Wayne Zschech <span dir="ltr"><<a href="mailto:waynezschech@calvarychapel.com">waynezschech@calvarychapel.com</a>></span> wrote:<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">G'day all!<br><br>Greetings from very frozen Ukraine! <br><br>Does anyone have any experience in using dry digestion? I am planning on using food waste and grass, leaves etc. I am hoping to avoid adding water which creates a very diluted fertilizer and I presume that there would be an increases in energy consumption of trying to keep (or reheat) all that liquid in a low solid system.<br>
I really like the OWS Dranco type of configuration. I have been told that the thermophilic reaction is more unstable in general but maybe someone still has a working model that is simple enough to run on small scale or around 20-25m3. I am happy to do a multistage process if I can get a more concentrated NPK product.<br>
<br>Please share any info that may be beneficial.<br>Blessings,<br>Wayne<br>
<br>_______________________________________________<br>
Digestion mailing list<br>
<br>
to Send a Message to the list, use the email address<br>
<a href="mailto:Digestion@bioenergylists.org">Digestion@bioenergylists.org</a><br>
<br>
to UNSUBSCRIBE or Change your List Settings use the web page<br>
<a href="http://lists.bioenergylists.org/mailman/listinfo/digestion_lists.bioenergylists.org" target="_blank">http://lists.bioenergylists.org/mailman/listinfo/digestion_lists.bioenergylists.org</a><br>
<br>
for more information about digestion, see<br>
Beginner's Guide to Biogas<br>
<a href="http://www.adelaide.edu.au/biogas/" target="_blank">http://www.adelaide.edu.au/biogas/</a><br>
and the Biogas Wiki <a href="http://biogas.wikispaces.com/" target="_blank">http://biogas.wikispaces.com/</a><br>
<br>
<br></blockquote></div><br></div></div>