Dear David,<br><br>My engineering book covers most of the written topics (Deublein & Steinhauser's <span class="il">Biogas</span> form waste and renewable resources (Willey, 2009)), encluding the biochemisty of the biogas formation from various sources (points 2. and 4.), but i guess pollution engineering handbook should do. I will get back to you with the references for the microbiological part.<br>
<br>Excuse me on my quick-fingers terminology, nor "stochiometric" or "stechiometric" but "stoichiometric" should do fine :)<br><br>BR, Gasan<br><br><br><div class="gmail_quote">On 23 March 2011 09:18, David Fulford <span dir="ltr"><<a href="mailto:davidf@kingdombio.com">davidf@kingdombio.com</a>></span> wrote:<br>
<blockquote class="gmail_quote" style="margin: 0pt 0pt 0pt 0.8ex; border-left: 1px solid rgb(204, 204, 204); padding-left: 1ex;">
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Dear Gasan and listers,<br>
<br>
This is the sort of information we need on the biogas wiki. Can you
provide us with some basic references (books, academic articles)
that we can use for this data, especially on item 2. This is the
clearest statement I have read on the relative proportions of
CH4/CO2 from various substrates.<br>
<br>
Do you mean stochiometric, or is stechiometric another term that we
need to learn?<br>
<br>
Thanks<br>
<br>
David F<div><div></div><div class="h5"><br>
<br>
On 23/03/2011 07:49, Gasan Osojnik wrote:
</div></div><blockquote type="cite"><div><div></div><div class="h5">Dear dr. Karve <br>
<br>
I do not wish to engage nor in a lengthy philosophical or
physiological debate, but I do have one or two points to make:<br>
<br>
1. Methanogenic archaea do not degrade sugar or even complex
substances, they use either acetate or hydrogen + carbon dioxide
to survive. They are old an primitive organisms, that originate
back to the beginning of life, even before glucose was formed by
other organisms, therefore they can feast on very basic energy
sources. There are not any other "methanogens" in other branches
of the evolution tree.<br>
2. The stechiometric ratio of methane/carbon dioxide fromation
from carbohydrates is CH4/CO2 = 50/50, from fats = 62.5/37.5 and
from proteins 71/29 (due to absorptive properties of the
sediment), so the number mentioned is presumably based on
anaerobic microbial protein degradation?<br>
3. The chain of microorganisms is not only highly likely, but is
confirmed by the means of certified analytical techniques, such as
the techniques of molecular biology and can be even seen under
the electron microscope. The sole biochemistry and the
termoenergetics of the methane formation process from polymers
reveal, that it is impossible for the process to start and finish
in only one type of unicellular procaryotic microorganisms (or any
other). We have pictures of microorganisms of species that are
literary "glued one another" for better substrate / intermediate
exchange, and this is no exception but a necessity for their
survival. Currently it is believed that around 800 species are
involved in the biogas formation community (not all at the same
time) but this number is increasing rapidly (e.g. 2008 this number
was around 400). Personally I believe this number to be much
greater, as methanogenic microbiota is found on very diverse parts
of the planet and is a common way of surviving in areas with no /
low oxygen concentrations.<br>
4. The issue of CO2 which has ben adressed needs some basic
insight in the process. The dissolved co2 that is produced
intermediately in the proceses of acetogenesis (some also in the
hydrolysis ans acetogenesis) is, as said, a substrate for the
production of methane, and is taken up very rapidly by the
archaea. Therefore, you should not look at the intermediate CO2 as
a product but as a reactant. As most of the biogas (at least up to
70%) is formed via acetate decarboxylation to methane and CO2. The
partial pressures of surplus CO2 equilibrate in the headspace of
the reactor and the liquid, so the CO2 that you get in biogas is
actualy mostly the product of acetoclastic methanogenesis.<br>
<br>
BR, Gasan<br>
<br>
<br>
Dear Mr. Afilal,<br>
if you used any substance that is digested by humans,(sugar,
starch,<br>
digestible protein or fat), it gets completely converted into
biogas by<br>
the methanogens. 1 kg of any of these substances would yield about
1 kg<br>
biogas, containing the theoretically calculated proportion of
roughly 25 to<br>
30% methane and 70 to 75% carbon dioxide. The presence of a chain
of<br>
micro-organisms, with each one producing a product that serves as
food for<br>
the next one in the chain is not believable. If it were really so,
one would<br>
get a much higher concentration of carbon dioxide in the resultant
biogas,<br>
because the intermediate organisms produce only carbon dioxide and
not<br>
methane.<br>
Yours<br>
A.D.Karve<br>
<br>
<br>
<br>
<div class="gmail_quote">On 22 March 2011 20:00, <span dir="ltr"><<a href="mailto:digestion-request@lists.bioenergylists.org" target="_blank">digestion-request@lists.bioenergylists.org</a>></span>
wrote:<br>
<blockquote class="gmail_quote" style="margin: 0pt 0pt 0pt 0.8ex; border-left: 1px solid rgb(204, 204, 204); padding-left: 1ex;">Re: The biology of biogas production</blockquote>
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<div>-- <br>
<p align="center">********************************************************************<br>
Dr David Fulford CEnv MEI, 15, Brandon Ave, Woodley, Reading RG5
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