<span>Thank you everybody.</span><br /><span>Jacopo</span><br /><span> </span><br /><span> </span><br /><span>-----Messaggio originale-----</span><br /><span>Da: David <david@h4c.org></span><br /><span>Inviato il: 27 Set 2011 - 22:26</span><br /><span>A: digestion@lists.bioenergylists.org</span><br /><span><br /><br /> <span style="font-family: Georgia;"><br /> Les, all,<br /> </span><br /> On 9/23/2011 11:19 AM, Les Gornall wrote:</span><br /><blockquote cite="mid:FDF52A7D-F318-4B22-A2D4-5F291C3FEE2D@projen.co.uk"><spanre>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><span><br /> A more ubiquitous high silica plant, at least around here (Oregon) where I live is equisteum, variously known as scouring rush and horsetail.</span><br /> <blockquote cite="mid:FDF52A7D-F318-4B22-A2D4-5F291C3FEE2D@projen.co.uk"><spanre>When digested the silicone would most likely be expresses as siloxanes in the Biogas. But I have not seen any data. </pre></blockquote><span><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:</span><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><span><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.</span><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></div></div></div>
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