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Les, all,<br>
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On 9/23/2011 11:19 AM, Les Gornall wrote:
<blockquote
cite="mid:FDF52A7D-F318-4B22-A2D4-5F291C3FEE2D@projen.co.uk"
type="cite">
<pre wrap="">Good question! The [arundo donax (giant reed)] is unique in it's ability to lock silicon into its stem tissues. That's why it is used for making oboe reeds. </pre>
</blockquote>
<br>
A more ubiquitous high silica plant, at least around here (Oregon)
where I live is equisteum, variously known as scouring rush and
horsetail.<br>
<br>
<blockquote
cite="mid:FDF52A7D-F318-4B22-A2D4-5F291C3FEE2D@projen.co.uk"
type="cite">
<pre wrap="">When digested the silicone would most likely be expresses as siloxanes in the Biogas. But I have not seen any data. </pre>
</blockquote>
<br>
I tend to doubt that any resulting biogas would have siloxanes in
it. It's not my area of expertise, but my understanding is that the
siloxanes found in landfill gas are not "built up" from any natural
silica compounds, as would have to be the case if they were to be
produced simply because one is digesting natural organic matter that
has a lot of silica, but rather they result from the decomposition
of artificial silicates:<br>
<br>
<blockquote>
Volatile Methyl Siloxanes (VMS) are the result of hydrolysis of
Polydimethylsiloxane (PDMS), an organosilicon compound which is
used in a wide range of consumer applications. Due to its
widespread use, PDMS is deposited in landfill where it degrades in
lower molecular weight compounds (VMS). PDMS can also enter the
wastewater treatment plants were, because of its insolubility in
water, partitions to the sludge. Consequently, when this is fed to
anaerobic digester, PDMS can hydrolyse to VMS.<br>
<br>
The species detected by now in biogas are
hexamethylcyclotrisiloxane (D3), decamethyl-cyclopentasiloxane
(D5), octamethylcyclotetrasiloxane (D4), hexamethyldisiloxane
(L2), octamethyltrisiloxane (L3). The concentration values depend
on the origin of the biogases. [found <a
href="http://www.tf.uniag.sk/Biohydrogen/state.htm">here</a>]<br>
</blockquote>
<br>
<br>
I am not familiar with giant reed grass, but I have seen reeds of
the sort used in instruments, and clearly one of the main
characteristics of those reeds is their stiffness; they have to
vibrate to fulfill their function. If that is characteristic of the
plant generally-- stiff, woody-- then I think it would make a very
poor biogas substrate unless it was harvested while still at a
tender stage, or perhaps exposed to fungi post-harvest. I would in
general assume that one could learn more about pretreatment options
by researching what is done with more widely used crops of the same
general sort-- miscanthus, switchgrass, et al.<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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