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Dear Isiaka,<br>
<br>
<br>
<div class="moz-cite-prefix">On 9/24/2012 3:13 AM,
<a class="moz-txt-link-abbreviated" href="mailto:multicareng@yahoo.com">multicareng@yahoo.com</a> wrote:<br>
</div>
<blockquote
cite="mid:899342218-1348481606-cardhu_decombobulator_blackberry.rim.net-175420507-@b27.c16.bise7.blackberry"
type="cite">
I am working on biogas application on farm and low / middle class
homes.
[...]<br>
<br>
I am looking for simplest and easiest way(s) to eliminate hydrogen
sulphide from biogas and I think you can be of assistance.
<br>
</blockquote>
<br>
In addition to the excellent advice and information you have already
gotten, I would mention that there is a low-cost means of measuring
the amount of H<sub>2</sub>S in the biogas detailed in a freely
downloadable PDF from The Complete Biogas Handbook website, <a
href="http://completebiogas.com/PDFs/BiogasHandbook_A01_analysis.pdf">here</a>.<br>
<br>
Further, the following is from the same book:<br>
<br>
<blockquote>
<blockquote>
Henry (1961) claims that at mesophilic temperatures and pH 5.0,
98% of all of the sulfides dissolved in the slurry show up as H<sub>2</sub>S,
whereas
at pH 7.2, this is reduced to 24% with an approximate 50%
reduction for each 0.2 pH unit increase thereafter (e.g., 12% at
7.4, 6% at 7.6, 3% at 7.8, 1.5 % at 8.0). Where scrubbing H<sub>2</sub>S
is desirable but unrealistic for some reason, pH adjustment may
be the answer— but take care not to over-adjust. A further idea
is the addition of the ferric ion of iron; Henry used ferric
chloride at the rate of about 2 grams per liter. This tied up
the sulfide ion and no H<sub>2</sub>S was produced in a digester
with this high dosage of ferric chloride.<br>
</blockquote>
</blockquote>
<br>
For a good recipe for creating a mixture that will assist scrubbing
of H<sub>2</sub>S-- remembering the caveats mentioned by Alex-- I
suggest looking at the booklet "Some Conditions Affecting the
Usefulness of Iron Oxide for City Gas Preparation", by William. A.
Dunkley (February, 1921). It can be downloaded from <a
href="http://ia600400.us.archive.org/14/items/someconditionsaf00dunkrich/someconditionsaf00dunkrich.pdf">here</a>.<br>
<br>
My final thought is that we may ultimately find the best means of
scrubbing H<sub>2</sub>S from biogas is by the use of sulfur-loving
bacteria. However, to the best of my knowledge, no one has yet
adapted this relatively high-tech process to low-tech-- i.e.
village-- use. (One of the key hurdles to overcome, for example, is
that these bacteria need just a hint of oxygen in order to
metabolize the H<sub>2</sub>S into elemental S.) I would love to
hear of anyone that has ideas or sources of information on this.
Some steps in this direction are indicated (for example) by a thesis
by Mary Elizabeth Fischer, "Biogas Purification: H2S Removal using
Biofiltration," available <a
href="http://uwspace.uwaterloo.ca/bitstream/10012/5458/1/Mary%20Elizabeth%20Fischer,%202010.pdf">here</a>.<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>
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<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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