Dear Isiaka,
On 9/24/2012 3:13 AM, [email protected] wrote:
I am working on biogas application on farm and low / middle class
homes. [...]
I am looking for simplest and easiest way(s) to eliminate hydrogen
sulphide from biogas and I think you can be of assistance.
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_2 S in the biogas detailed in a freely downloadable
PDF from The Complete Biogas Handbook website, here
<http://completebiogas.com/PDFs/BiogasHandbook_A01_analysis.pdf>.
Further, the following is from the same book:
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_2 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_2 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_2 S was produced in a digester with this high dosage of
ferric chloride.
For a good recipe for creating a mixture that will assist scrubbing of
H_2 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 here
<http://ia600400.us.archive.org/14/items/someconditionsaf00dunkrich/someconditionsaf00dunkrich.pdf>.
My final thought is that we may ultimately find the best means of
scrubbing H_2 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_2 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 here
<http://uwspace.uwaterloo.ca/bitstream/10012/5458/1/Mary%20Elizabeth%20Fischer,%202010.pdf>.
d.
--
David William House
"The Complete Biogas Handbook" |www.completebiogas.com|
/Vahid Biogas/, an alternative energy consultancy |www.vahidbiogas.com
|
|
"Make no search for water. But find thirst,
And water from the very ground will burst."
(Rumi, a Persian mystic poet, quoted in /Delight of Hearts/, p. 77)
http://bahai.us/
|
_______________________________________________
Digestion mailing list
to Send a Message to the list, use the email address
[email protected]
to UNSUBSCRIBE or Change your List Settings use the web page
http://lists.bioenergylists.org/mailman/listinfo/digestion_lists.bioenergylists.org
for more information about digestion, see
Beginner's Guide to Biogas
http://www.adelaide.edu.au/biogas/
and the Biogas Wiki http://biogas.wikispaces.com/
