[Digestion] Digestion Digest, Vol 25, Issue 9
Vishwas Gokhale
vishwasgokhale860 at gmail.com
Sat Sep 29 00:14:33 CDT 2012
Ref: Sandra,
If you remove in external column with with fish aerator it is always
better and safer. The column should be packed with plastic packing and
can be designed for about 3 kg BOD /cum/day of plastic packing . The
slurry from digester can be used for seeding and stabilization could be
achieved within 20 to 30 days. You can use the gas thereafter for the
genset after cooling the same for moisture removal. This way you can
prevent digester upset if the feedstock is other than cowdung.
Vishwas Gokhale
On Sat, Sep 29, 2012 at 12:30 AM, <
digestion-request at lists.bioenergylists.org> wrote:
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> Today's Topics:
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> 1. Removal of hydrogen sulphide from biogas (Sandra) (sandra bos)
> 2. Re: Removal of hydrogen sulphide from biogas (Sandra)
> (alexanderb.eaton at gmail.com)
>
>
> ----------------------------------------------------------------------
>
> Message: 1
> Date: Fri, 28 Sep 2012 09:53:00 +0200
> From: sandra bos <sandra-bos at live.nl>
> To: "digestion at lists.bioenergylists.org"
> <digestion at lists.bioenergylists.org>
> Subject: [Digestion] Removal of hydrogen sulphide from biogas (Sandra)
> Message-ID: <SNT125-W306DA14C55F0226D42485498820 at phx.gbl>
> Content-Type: text/plain; charset="iso-8859-1"
>
>
> Dear Alex,
>
> I would like to share with you our solution for H2S removal.
> We have a biogas project in Uganda where we convert biogas into
> electricity with a 12kW gas generator.
> We remove the H2S with a small aquarium pump by pumping approximately 3%
> air into the gas mixture.
> In our case, we use the Schego Triumph Extra electronic 12V 180l/h. The
> Schego pumps also exist in 150l/h.
> So you can just calculate the 3% of your gas mixture to know how many
> hours your pump has to run.
> You could install a small solar system/ or just use a small 12V battery to
> run your air pump.
>
> Good luck,
>
> Best regards,
>
> Sandra Bos
> www.fact-foundation.com
>
> >
> > ----------------------------------------------------------------------
> >
> > Message: 1
> > Date: Wed, 26 Sep 2012 12:34:44 -0700
> > From: David <david at h4c.org>
> > To: alexanderb.eaton at gmail.com
> > Cc: multicareng at yahoo.com, For Discussion of Anaerobic Digestion
> > <digestion at lists.bioenergylists.org>
> > Subject: Re: [Digestion] Removal of hydrogen sulphide from biogas
> > Message-ID: <506358D4.6030401 at h4c.org>
> > Content-Type: text/plain; charset="iso-8859-1"; Format="flowed"
> >
> >
> >
> > Alex,
> >
> > On 9/25/2012 1:53 PM, alexanderb.eaton at gmail.com wrote:
> > > David,
> > >
> > > Some really interesting points here. For example, any idea how much
> > > ferric oxide would make sense to add to a digester? How would that
> > > effect the effluent as a fertilizer?
> >
> > Well of course the question before your question has been mentioned
> > already, which is whether one needs to do anything at all. I don't
> > think it makes sense to do a preemptive strike on H_2 S, but rather
> > find out if it will be a problem, then if it is, to deal with it. And
> > of course whether it may be a problem depends on a number of factors.
> > And remembering that the original question was about small-scale, farm
> > or household digestion, of the millions of Chinese- and Indian-style
> > digesters extant, I don't know of any significant use of scrubbing H_2
> > S that is used. Your thought appears to be the same since you say "In
> > the SNV program they essentially use no filtration, and they really do
> > not have issues."
> >
> > That said, using one of the methods mentioned by Henry of adding a
> > source of the ferric ion, based on the figures he presents-- and they
> > were minimal in his paper-- one would need 2 g Fe_2 O_3 /l of slurry.
> > That can end up being quite a lot of material.
> >
> > But it is important to note that Henry does not assert that this is a
> > well-tested dosage. In fact, according to his paper, he tried this
> > technique only twice-- not with a range of dosages, in a series of
> > digesters with varying amounts of sulfides, but only two times, once
> > each in two test digesters. He says that
> >
> > "It can be seen that the amount of sulfide in the sludge in a
> > digester is not a measure of the hydrogen sulfide in the
> > digester gases. The sulfide may be tied, as in this case, with
> > iron [DWH: i.e. often by adding it]. The iron content, of
> > course, is not an exact figure. Any small bit of rust would
> > have shown up too."
> >
> >
> > So even the 2g/l figure is "more or less", and really this comes down
> > to a sort of general guideline: if one has "too much" H2S in the
> > biogas, then try adding "some" rust (or perhaps a bit of
> > iron-containing soil, such as hematite) to the slurry.
> >
> >
> > > My sense is that the sulpher and iron would actually work well as
> > > micro nutrients, as both would be present in high concentrations. We
> > > could make a powdered mixture with cal (lyme?) To both raise pH and
> > > add the iron. Both materials are really cheap and effective in small
> > > volumes.
> >
> > S (more likely) and Fe (less likely) might be micro-nutrients, but
> > that would depend on the soil to which the effluent is being added.
> > And even cheap materials, given that one would have to mix and add
> > them, have a marginal cost in labor and complexity, so again either
> > additive should earn its place following some degree of proof that it
> > was actually needed, or sufficiently beneficial to warrant inclusion.
> >
> >
> > > Regarding the biological filtration, I think the thesis you posted
> > > talks about running the gas through a drier mix of cow manure.
> >
> > The cow manure filtration actually is mentioned in a different paper,
> > although at the moment I don't have the time to track it down. The
> > thesis I mentioned offers a lot of information that might be adapted
> > to lower-tech biofiltration of H_2 S.
> >
> >
> > > I have seen the industrial systems (RCM International a really
> > > impressive model), but I have not been able work through the pumping
> > > of substrate and air at a small scale.
> >
> > Any digester evolving biogas will provide enough pressure to cause the
> > biogas to flow. The problem, as you indicate, would be getting enough
> > but not too much air into the gas stream just before the point of
> > exposure to whatever media was supporting the sulfur-loving bacteria.
> >
> >
> > > Aside from engines, the question that SNV made me ask was: why
> > > filter for small systems? If the combustion is complete the sulphur
> > > becomes elemental, with a slight odor but not dangerous, or at least
> > > how I understand it. We have never registered any dangerous sulphur
> > > compositions in a kitchen. Thoughts?
> >
> > Actually when H_2 S is burned, it produces SO_2 , which is quite
> > irritating (that concentrations of three to five PPM are readily
> > detectable). Further, in the presence of water (and when the exhaust
> > gases cool, water will be present), SO_2 combines to produce sulfurous
> > acid (H_2 SO_3 ), which can corrode appliances, flues, and the like. I
> > use sulfur to control gophers on my farm, for example, by putting some
> > elemental sulfur in a run that I've dug up, then burning it into the
> > burrow with a propane torch. Believe me, it's sufficiently deadly.
> >
> > I think, in sum, that the reason so little scrubbing is done is
> > because few substrates contain sufficient sulfur to be of much
> > concern, and those which do contain sulfur in some form (pig manure,
> > for example) are generally digested at a pH sufficient to reduce the
> > production of H_2 S (and/or there is sufficient ferric ion present--
> > widely available in soil and water-- to suppress the production of H_2
> > S) that it simply is not a problem in most situations.
> >
> >
> >
> > 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/
> > |
> > -------------- next part --------------
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> >
> > ------------------------------
> >
> > Message: 2
> > Date: Thu, 27 Sep 2012 06:04:58 +0530
> > From: Anand Karve <adkarve at gmail.com>
> > To: For Discussion of Anaerobic Digestion
> > <digestion at lists.bioenergylists.org>
> > Subject: Re: [Digestion] Removal of hydrogen Sulphide from biogas
> > Message-ID:
> > <CACPy7ScV4KvtE5qWcm+Zy=-
> n2fvEq35Uaq3oneHJgDRsLXh5yQ at mail.gmail.com>
> > Content-Type: text/plain; charset="iso-8859-1"
> >
> > Dear Mr. Taiwo,
> > passing biogas through a cylinder filled with iron filings or steel wool
> > would remove the hydrogen sulphide. The iron filings would turn black by
> > being converted into iron sulphide. Such blackened iron filings have to
> be
> > periodically changed.
> > Yours
> > A.D.Karve
> >
> > On Tue, Sep 25, 2012 at 11:26 AM, Isiaka Taiwo
> > <wealthofnature at hotmail.com>wrote:
> >
> > > Dear sir,
> > >
> > > I am an Electrical Engineer from Nigeria.
> > >
> > > I am working on biogas application on farm and low / middle class
> homes.
> > >
> > > My objective is to use biogas for cooking, running of small power
> > > generators and lighting of gas lamps.
> > >
> > > I have accomplished the production of biogas from my biogas digester,
> and
> > > I have burnt the gas and it gave blue flame.
> > >
> > > I have also converted a petrol generator to gas generator with a
> converter
> > > I bought in country.
> > >
> > > I am delaying the test of the generator with biogas because of the
> > > corrosive effect of the gas which I learnt can damage the generator.
> Also ,
> > > I want to protect lives of the stakeholders as the hydrogen sulphide is
> > > also poisonous.
> > >
> > > I am looking for simplest and easiest do it yourself (DIY) way(s) to
> > > eliminate hydrogen sulphide from biogas and I think you can be of
> > > assistance.
> > >
> > > I don't mind suggestion of suppliers of any ready made solution.
> > >
> > > Please , I am waiting for any assistance or useful information that
> will
> > > help in realisation of my set objectives.
> > >
> > > Thanks for the anticipated assistance and supports.
> > >
> > >
> > > Isiaka Taiwo
> > > Sent from my BlackBerry wireless device from MTN
> > >
> > > _______________________________________________
> > > Digestion mailing list
> > >
> > > to Send a Message to the list, use the email address
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> > >
> 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/
> > >
> > >
> >
> >
> > --
> > ***
> > Dr. A.D. Karve
> > Trustee & Founder President, Appropriate Rural Technology Institute
> (ARTI)
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> > ------------------------------
> >
> > _______________________________________________
> > Digestion mailing list
> >
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> > 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/
> >
> >
> >
> > End of Digestion Digest, Vol 25, Issue 8
> > ****************************************
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> ------------------------------
>
> Message: 2
> Date: Fri, 28 Sep 2012 13:02:51 +0000
> From: alexanderb.eaton at gmail.com
> To: "For Discussion of Anaerobic Digestion"
> <digestion at lists.bioenergylists.org>
> Subject: Re: [Digestion] Removal of hydrogen sulphide from biogas
> (Sandra)
> Message-ID:
>
> <831100920-1348837373-cardhu_decombobulator_blackberry.rim.net-794025609- at b14.c13.bise6.blackberry
> >
>
> Content-Type: text/plain
>
> Thanks Sandra,
>
> That seems like a really good option! What have your removal efficiencies
> been at 3 percent?
>
> Is the air injected to the reactor, a gas storage container or the gas
> line during use of the generator?
>
> Have you added safety precautions, or do you focus on capacity building to
> avoid adding too much air?
>
> Thanks in advance for explaining a bit more!
>
> Best,
>
> A
> Sent via BlackBerry by AT&T
>
> -----Original Message-----
> From: sandra bos <sandra-bos at live.nl>
> Sender: digestion-bounces at lists.bioenergylists.org
> Date: Fri, 28 Sep 2012 09:53:00
> To: digestion at lists.bioenergylists.org<digestion at lists.bioenergylists.org>
> Reply-To: For Discussion of Anaerobic Digestion
> <digestion at lists.bioenergylists.org>
> Subject: [Digestion] Removal of hydrogen sulphide from biogas (Sandra)
>
> _______________________________________________
> Digestion mailing list
>
> to Send a Message to the list, use the email address
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> to UNSUBSCRIBE or Change your List Settings use the web page
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>
> 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/
>
>
>
> ------------------------------
>
> _______________________________________________
> Digestion mailing list
>
> to Send a Message to the list, use the email address
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> 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/
>
>
>
> End of Digestion Digest, Vol 25, Issue 9
> ****************************************
>
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