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Paul,<br>
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On 10/7/2011 5:41 PM, Paul Harris wrote:
<blockquote
cite="mid:008401cc8552$f771bae0$e65530a0$@harris@adelaide.edu.au"
type="cite">
<pre wrap="">G'day All,
David House's book "The biogas handbook" has a bit about carbon and charcoal and he does not seem to expect any assistance, possibly inhibition. I guess a lot depends on how the carbon is prepared and what the substrate may be.</pre>
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<br>
Appreciate the mention, Paul, and I hope you are well.<br>
<br>
I assume you are referring to pp. 65-66, where some work done in
1971 by
Laura and Idnani (Increased Production of Biogas from Cowdung by
Adding Other Agricultural Waste Materials. J. of the Sciences of
Food and Agriculture 22:164) is discussed:<br>
<br>
<blockquote>
<p>"Oddly, the addition of either leguminous leaves alone (peas,
alfalfa) or non-leguminous leaves alone did not stimulate biogas
production very much, although there was some result. The
addition of cane sugar alone, or what they refer to as “sarson
oil cake” alone, or filter paper (essentially pure cellulose)
alone, had no effect on the total amount of gas produced. Ashes
and charcoal both reduced gas production, charcoal rather
dramatically. (Although some researchers claim that activated
charcoal helps city sewage digestion and gas production.)"</p>
</blockquote>
<br>
I agree with you that the source of and method for producing the
charcoal will very likely have an impact on the result. (In my
current project-- a 10 cu m food waste digester in a solar
greenhouse-- if I can find a good source I have been planning to use
bamboo charcoal, for reasons that I will not mention here since I
may well be wrong...)<br>
<br>
Of course, several steps in the biogas process are rate-limited,
particularly (depending on substrate) the first stage, hydrolysis.
For this and other reasons, <i>if the mode of action is focused on
methanogenisis</i>, I would not expect dramatic improvements in
the rate of gas production, particularly on the rate of methane
production. However, whereas as I believe you indicated biofilms
will have a lot of surface to colonize in most substrates that have
any solid material, nevertheless it would seem that if the charcoal
were in a mesh bag and anchored near the inlet to a digester,
colonization of incoming substrates would take place at an
accelerated rate. Where the bitty buddies get started faster, then
it would stand to reason that the whole process would be somewhat
accelerated, although I doubt I will be seeing a 3x increase.<br>
<br>
Some other possible modes of action have already been mentioned, but
I might just draw a distinction between absorption and adsorption;
the latter is more of a surface phenomena, and may in some way
assist the utilization of fatty acids because they would tend to be
oriented similarly across a surface... I am only speculating,
however.<br>
<br>
<br>
<br>
d.<br>
<div class="moz-signature">-- <br>
<div style="font:Georgia" ;=""><span style="font-size:110%;">David
William House<br>
</span>
<div style="padding-left:3em;font-size:80%;">"The Complete
Biogas Handbook" <code><a href="www.completebiogas.com">www.completebiogas.com</a></code><br>
<em>Vahid Biogas</em>, an alternative energy consultancy <code><a
href="www.vahidbiogas.com">www.vahidbiogas.com</a><br>
<br>
</code></div>
<div style="padding-left:2em;">"Make no search for water.
But find thirst,<br>
And water from the very ground will burst."
<div style="padding-left:2em;font-size:80%;">(Rumi, a Persian
mystic poet, quoted in <em>Delight of Hearts</em>, p. 77) <br>
<br>
<a class="moz-txt-link-freetext" href="http://bahai.us/">http://bahai.us/</a></div>
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