<div dir="ltr">Dear Paul,<div>the so called ideal C/N value of 20 to 30 represents the C/N of cattle dung, which is not an ideal feedstock. Almost 90% of the dry weight of dung consists of non-digestible matter. Only the mucus and the load of bacteria in the dung are digestible. I reproduce below the part of my original article to clarify what I meant::</div><div> <span style="font-size:12.8px;line-height:19.2px;text-indent:48px">Textbooks lay a lot of emphasis on a value called Carbon/Nitrogen (C/N) ratio of the feedstock. The textbooks state 25 to be the ideal C/N ratio. This is the C/N ratio of dung, but it is a relic of the past when dung was universally considered to be the ideal feedstock. It has already been discussed how dung, representing the effluent slurry of a living biogas plant, can hardly be considered to be the ideal feedstock. Sugars, starches, cellulose, fats and digestible proteins show 100% digestibility. Of these substances, sugars, starches, cellulose and fats have C/N=</span><b style="font-size:12.8px;line-height:19.2px;text-indent:48px"><span style="font-family:'Times New Roman',serif">∞, </span></b><span style="font-size:12.8px;line-height:19.2px;text-indent:48px">whereas the C/N ratio of proteins is just 4 or 5. And yet, all of them show the v.s.% value of 100. One should realize that as a living system, a biogas plant requires all the inorganic components that a living cell needs, and that it is illogical to take only the nitrogen content of the system into consideration.</span></div><div><span style="font-size:12.8px;line-height:19.2px;text-indent:48px">Yours</span></div><div><span style="font-size:12.8px;line-height:19.2px;text-indent:48px">A.D.Karve</span></div></div><div class="gmail_extra"><br clear="all"><div><div class="gmail_signature" data-smartmail="gmail_signature">***<br>Dr. A.D. Karve<br><br>Chairman, Samuchit Enviro Tech Pvt Ltd (<a href="http://www.samuchit.com" target="_blank">www.samuchit.com</a>)<br><br>Trustee & Founder President, Appropriate Rural Technology Institute (ARTI)<br></div></div>
<br><div class="gmail_quote">On Wed, Jun 8, 2016 at 11:45 AM, Paul Harris <span dir="ltr"><<a href="mailto:harrisfm@aapt.net.au" target="_blank">harrisfm@aapt.net.au</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
<div bgcolor="#FFFFFF" text="#000000">
G'day All,<br>
<br>
While I am happy to agree to differ on some of Dr A,D.Karve's ideas
I disagree with points 6) and 7) below (if taken at face value).<br>
<br>
6) There should be a C:N ratio of approximately 20-30:1. The exact
value is not critical, but microbes need both these nutrients (and
other elements) to survive. Too much N will result in ammonia and
too much C probably reduces the biogas quality.<br>
<br>
7) Retention Time (RT) is reasonably important! Too short a RT
results in "washout", which stops digestion. The actual "washout" RT
depends on operating temperature, as this influences microbial
growth rate. Best use of digester volume occurs at a RT about twice
the "washout" time, but longer RTs result in more biogas per unit
influent and more robust operation.<br>
<table style="border-collapse:collapse;width:224pt" border="0" width="300" cellpadding="0" cellspacing="0">
<colgroup><col style="width:56pt" span="4" width="75"> </colgroup><tbody>
<tr style="height:13.5pt" height="18">
<td style="height:13.5pt;width:56pt" height="18" width="75"><br>
</td>
<td style="width:56pt" width="75"><br>
</td>
<td colspan="2" style="border-right:1.0pt solid black;width:112pt" width="150">Retention Time</td>
</tr>
<tr style="height:12.75pt" height="17">
<td style="height:12.75pt" height="17">Temp.</td>
<td style="border-left:none">Gwth Rte</td>
<td style="border-top:none;border-left:none">Washout</td>
<td style="border-top:none">"Optimum"</td>
</tr>
<tr style="height:15.0pt" height="20">
<td style="height:15.0pt;border-top:none" height="20">(<font><sup>O</sup></font><font>C)</font></td>
<td style="border-top:none;border-left:none">(days<font><sup>-1</sup></font><font>)</font></td>
<td style="border-top:none;border-left:none">(days<font>)</font></td>
<td style="border-left:none">(days<font>)</font></td>
</tr>
<tr style="height:12.75pt" height="17">
<td style="height:12.75pt" height="17">5</td>
<td style="border-left:none">0.020</td>
<td style="border-left:none">49.0</td>
<td style="border-left:none">97.9</td>
</tr>
<tr style="height:12.75pt" height="17">
<td style="height:12.75pt;border-top:none" height="17">10</td>
<td style="border-top:none;border-left:none">0.034</td>
<td style="border-top:none;border-left:none">29.4</td>
<td style="border-top:none;border-left:none">58.9</td>
</tr>
<tr style="height:12.75pt" height="17">
<td style="height:12.75pt;border-top:none" height="17">15</td>
<td style="border-top:none;border-left:none">0.056</td>
<td style="border-top:none;border-left:none">17.7</td>
<td style="border-top:none;border-left:none">35.5</td>
</tr>
<tr style="height:12.75pt" height="17">
<td style="height:12.75pt;border-top:none" height="17">20</td>
<td style="border-top:none;border-left:none">0.093</td>
<td style="border-top:none;border-left:none">10.8</td>
<td style="border-top:none;border-left:none">21.6</td>
</tr>
<tr style="height:12.75pt" height="17">
<td style="height:12.75pt;border-top:none" height="17">25</td>
<td style="border-top:none;border-left:none">0.150</td>
<td style="border-top:none;border-left:none">6.7</td>
<td style="border-top:none;border-left:none">13.3</td>
</tr>
<tr style="height:12.75pt" height="17">
<td style="height:12.75pt;border-top:none" height="17">30</td>
<td style="border-top:none;border-left:none">0.233</td>
<td style="border-top:none;border-left:none">4.3</td>
<td style="border-top:none;border-left:none">8.6</td>
</tr>
<tr style="height:12.75pt" height="17">
<td style="height:12.75pt;border-top:none" height="17">35</td>
<td style="border-top:none;border-left:none">0.336</td>
<td style="border-top:none;border-left:none">3.0</td>
<td style="border-top:none;border-left:none">6.0</td>
</tr>
<tr style="height:12.75pt" height="17">
<td style="height:12.75pt;border-top:none" height="17">40</td>
<td style="border-top:none;border-left:none">0.434</td>
<td style="border-top:none;border-left:none">2.3</td>
<td style="border-top:none;border-left:none">4.6</td>
</tr>
<tr style="height:13.5pt" height="18">
<td style="height:13.5pt;border-top:none" height="18">45</td>
<td style="border-top:none;border-left:none">0.502</td>
<td style="border-top:none;border-left:none">2.0</td>
<td style="border-top:none;border-left:none">4.0</td>
</tr>
</tbody>
</table>
<br>
I hope this is some help,<br>
<pre cols="72">HOOROO
Mr Paul Harris</pre><div><div class="h5">
<div>On 06-Jun-16 1:30 PM, Anand Karve
wrote:<br>
</div>
<blockquote type="cite">
<div dir="ltr">
<p class="MsoNormal" style="text-align:center" align="center"><b>Biogas
technology revisited</b></p>
<p class="MsoNormal" style="text-align:center" align="center">Dr.A.D.Karve</p>
<p class="MsoNormal" style="text-align:center" align="center">Samuchit
Enviro Tech
P. Ltd. Law College Road, Ekata Park Co-Op. Housing Society,
Behind Nirmitee
Showroom, Erandawane, Pune 411 004 (<a href="mailto:adkarve@gmail.com" target="_blank">adkarve@gmail.com</a>)</p>
<p class="MsoNormal" style="line-height:150%">Abstract: In spite
of new knowledge
gained since the advent of the 21<sup>st</sup> century the
biogas researchers still
use some of the older concepts. The new
concepts pointed out in this article are 1) Because the biogas
producing
microbes reside in the intestines of animals, they eat what
the animals eat. 2)
Breeding super-methanogens can be achieved, but their use in a
biogas plant
would not be practical, as it would be impossible to maintain
them. 3) All
animals represent living biogas plants, and therefore the
fecal matter of
animals is the effluent slurry of a biogas plant. The biogas
producing microbes
are found universally in the fecal matter of animals because
they exit the
animal body along with dung. 4)Even the
anaerobic microbes need oxygen for their metabolism. They
extract the
chemically bound oxygen from their feedstock. Therefore,
feedstock of a biogas plant must
have oxygen in its chemical make up. The same is also true of
food eaten by
animals. 5)The value called % volatile solids actually
represents the %
digestibility of the concerned substance. 6)There is no
justification for
laying emphasis on the C/N ratio of a feedstock. 7) There is
no justification
for laying emphasis on the hydraulic retention time of a
biogas plant. It is a
useless concept. 8) In a biphasic system, the feedstock is
first treated
aerobically and then subjected to anaerobic conditions. This
is wrong, because
most of the organic carbon, which would have yielded methane
in the anaerobic
phase, gets oxidized in the aerobic phase itself, leading to
drastic reduction
in the methane yield.</p>
</div>
<div class="gmail_extra"><br clear="all">
<div>
<div data-smartmail="gmail_signature">***<br>
Dr. A.D. Karve<br>
<br>
Chairman, Samuchit Enviro Tech Pvt Ltd (<a href="http://www.samuchit.com" target="_blank"></a><a href="http://www.samuchit.com" target="_blank">www.samuchit.com</a>)<br>
<br>
Trustee & Founder President, Appropriate Rural
Technology Institute (ARTI)<br>
</div>
</div>
<br>
<div class="gmail_quote">On Mon, Jun 6, 2016 at 6:44 AM, Kelvin
masule <span dir="ltr"><<a href="mailto:kmasule97@gmail.com" target="_blank">kmasule97@gmail.com</a>></span>
wrote:<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
<p>Guys do u have any information about biogas? </p>
<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" target="_blank">Digestion@bioenergylists.org</a><br>
<br>
to UNSUBSCRIBE or Change your List Settings use the web page<br>
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<br>
for more information about digestion, see<br>
Beginner's Guide to Biogas<br>
<a href="http://www.adelaide.edu.au/biogas/" rel="noreferrer" target="_blank">http://www.adelaide.edu.au/biogas/</a><br>
and the Biogas Wiki <a href="http://biogas.wikispaces.com/" rel="noreferrer" target="_blank">http://biogas.wikispaces.com/</a><br>
<br>
<br>
</blockquote>
</div>
<br>
</div>
<br>
<fieldset></fieldset>
<br>
<pre>_______________________________________________
Digestion mailing list
to Send a Message to the list, use the email address
<a href="mailto:Digestion@bioenergylists.org" target="_blank">Digestion@bioenergylists.org</a>
to UNSUBSCRIBE or Change your List Settings use the web page
<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>
for more information about digestion, see
Beginner's Guide to Biogas
<a href="http://www.adelaide.edu.au/biogas/" target="_blank">http://www.adelaide.edu.au/biogas/</a>
and the Biogas Wiki <a href="http://biogas.wikispaces.com/" target="_blank">http://biogas.wikispaces.com/</a>
</pre>
</blockquote>
<br>
</div></div></div>
<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>
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<br>
for more information about digestion, see the Biogas Wiki <a href="http://biogas.wikispaces.com/" rel="noreferrer" target="_blank">http://biogas.wikispaces.com/</a><br>
<br>
<br></blockquote></div><br></div>