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<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'>G’day A.D. Karve et al,<o:p></o:p></span></p>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'><o:p> </o:p></span></p>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'>This post from a while back prompted an interesting thought –
if you are right we may be able to acclimate a digester to using just CO2 as
the carbon source, so we could convert CO2 back to methane and solve both CO2
emissions and “peak oil”.<o:p></o:p></span></p>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'><o:p> </o:p></span></p>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'>The quality ratio of CH4 to CO2 does vary a bit, sometimes being
less than 50% methane and sometimes claims of over 90% methane, but David
Fulford has shown that sugar and starch give 50% methane so any improvement is
due to some methanogens using CO2 produced earlier in the sequence and H+ from
water and acids to make CH4 and H2O.<o:p></o:p></span></p>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'><o:p> </o:p></span></p>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'>Happy digesting,<o:p></o:p></span></p>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'>HOOROO<o:p></o:p></span></p>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'><o:p> </o:p></span></p>
<p class=MsoNormal><span style='font-size:10.5pt;font-family:Consolas;
color:#1F497D'>Mr. Paul Harris, Room 202 Charles Hawker Building, Faculty of
Sciences, The University of Adelaide, Waite Campus, PMB 1, Glen Osmond SA
5064 Ph : +61 8 8303 7880
Fax : +61 8 8303 4386 <a
href="mailto:paul.harris@adelaide.edu.au"><span style='color:blue'>mailto:paul.harris@adelaide.edu.au</span></a>
<a href="http://www.adelaide.edu.au/directory/paul.harris"><span
style='color:blue'>http://www.adelaide.edu.au/directory/paul.harris</span></a><o:p></o:p></span></p>
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color:#1F497D'><o:p> </o:p></span></p>
<p class=MsoNormal><span style='font-size:10.5pt;font-family:Consolas;
color:#1F497D'>CRICOS Provider Number 00123M<o:p></o:p></span></p>
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<p class=MsoNormal><b><span lang=EN-US style='font-size:10.0pt;font-family:
"Tahoma","sans-serif"'>From:</span></b><span lang=EN-US style='font-size:10.0pt;
font-family:"Tahoma","sans-serif"'> digestion-bounces@lists.bioenergylists.org
[mailto:digestion-bounces@lists.bioenergylists.org] <b>On Behalf Of </b>Anand
Karve<br>
<b>Sent:</b> Thursday, 2 June 2011 12:50 PM<br>
<b>To:</b> digestion@lists.bioenergylists.org<br>
<b>Subject:</b> [Digestion] Fwd: The biology of biogas production<o:p></o:p></span></p>
</div>
<p class=MsoNormal><o:p> </o:p></p>
<p class=MsoNormal style='margin-bottom:12.0pt'><o:p> </o:p></p>
<div>
<p class=MsoNormal style='margin-bottom:12.0pt'>---------- Forwarded message
----------<br>
From: <b>Anand Karve</b> <<a href="mailto:adkarve@gmail.com">adkarve@gmail.com</a>><br>
Date: 2011/6/2<br>
Subject: Re: [Digestion] The biology of biogas production<br>
To: Gasan Osojnik <<a href="mailto:gasan.osojnik@gmail.com">gasan.osojnik@gmail.com</a>><br>
<br>
<o:p></o:p></p>
<div>
<p class=MsoNormal>Dear List,<o:p></o:p></p>
</div>
<div>
<p class=MsoNormal> Irrespective of the substrate, design of the system or
the temperature of the reaction, the proportion of methane to carbon dioxide in
the biogas seems to be constant all over the world. Is there an
equilibrium between these two gases that keeps this proportion
constant? Because in that case, one might introduce carbon dioxide from outside
into the biogas plant and see if the organisms in the digester
produce more methane to reach the euilibrium constant. I shall be grateful
to get your reaction on this. <o:p></o:p></p>
</div>
<div>
<p class=MsoNormal>Yours<o:p></o:p></p>
</div>
<div>
<p class=MsoNormal style='margin-bottom:12.0pt'>A.D.Karve <o:p></o:p></p>
</div>
<div>
<p class=MsoNormal>2011/3/22 Gasan Osojnik <<a
href="mailto:gasan.osojnik@gmail.com" target="_blank">gasan.osojnik@gmail.com</a>><o:p></o:p></p>
<div>
<div>
<p class=MsoNormal style='margin-bottom:12.0pt'>Hi Mohamed,<br>
<br>
The general (though I am sure there will be other interpretations) mechanism of
biogas formation is 4-step and involves:<br>
1. Hydrolysis (degradation of polymers)<br>
2. Acidogenesis (the formation of volatile fatty acids - low molecular
carboxylic acids)<br>
3. Acetogenesis (the formation of acetate, CO2 and H2)<br>
4. Methanogenesis (from acetete -> CO2 and CH4 is formed, from CO2 and H2
-> CH4 is formed, methanogenesis from acetate and CO2+H2 has to run
simultaneously for the proces to be stable) <br>
<br>
The last step is the reason why there will be always some CO2 in biogas. Each
of this steps is carried out by different groups of microorganisms.<br>
<br>
So the initial biochemical sources of biogas are carbohydrates, proteins, fats
etc. In the long run, any substance that can be converted intermediately either
to dissolved CO2 and H2 or to acetate is appropriate for biogas production.<br>
<br>
BR from Slovenia, Gasan<o:p></o:p></p>
</div>
<div>
<p class=MsoNormal> <o:p></o:p></p>
</div>
<div>
<p class=MsoNormal><b><span style='font-size:10.0pt;font-family:"Arial","sans-serif";
color:#990033'>Ilja Gasan OSOJNIK ÈRNIVEC, </span></b><span style='font-size:
10.0pt;font-family:"Arial","sans-serif"'>L05 - Laboratory for Environmental
Sciences and Engineering</span> <o:p></o:p></p>
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<p style='margin:0cm;margin-bottom:.0001pt'><span style='font-size:10.0pt;
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<p style='margin:0cm;margin-bottom:.0001pt'><span style='font-size:9.0pt;
font-family:"Arial","sans-serif"'>National Institute of Chemistry</span><o:p></o:p></p>
<p style='margin:0cm;margin-bottom:.0001pt'><span style='font-size:9.0pt;
font-family:"Arial","sans-serif"'>Hajdrihova 19</span><o:p></o:p></p>
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<p style='margin:0cm;margin-bottom:.0001pt'><span style='font-size:9.0pt;
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