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Dear Alex,<br><br>I would like to share with you our solution for H2S removal. <br>We have a biogas project in Uganda where we convert biogas into electricity with a 12kW gas generator.<br>We remove the H2S with a small aquarium pump by pumping approximately 3% air into the gas mixture. <br>In our case, we use the Schego Triumph Extra electronic 12V 180l/h. The Schego pumps also exist in 150l/h. <br>So you can just calculate the 3% of your gas mixture to know how many hours your pump has to run. <br>You could install a small solar system/ or just use a small 12V battery to run your air pump.<br><br>Good luck,<br><br>Best regards,<br><br>Sandra Bos<br>www.fact-foundation.com<br><br><div>> <br>> ----------------------------------------------------------------------<br>> <br>> Message: 1<br>> Date: Wed, 26 Sep 2012 12:34:44 -0700<br>> From: David <david@h4c.org><br>> To: alexanderb.eaton@gmail.com<br>> Cc: multicareng@yahoo.com, For Discussion of Anaerobic Digestion<br>> <digestion@lists.bioenergylists.org><br>> Subject: Re: [Digestion] Removal of hydrogen sulphide from biogas<br>> Message-ID: <506358D4.6030401@h4c.org><br>> Content-Type: text/plain; charset="iso-8859-1"; Format="flowed"<br>> <br>> <br>> <br>> Alex,<br>> <br>> On 9/25/2012 1:53 PM, alexanderb.eaton@gmail.com wrote:<br>> > David,<br>> ><br>> > Some really interesting points here. For example, any idea how much <br>> > ferric oxide would make sense to add to a digester? How would that <br>> > effect the effluent as a fertilizer? <br>> <br>> Well of course the question before your question has been mentioned <br>> already, which is whether one needs to do anything at all. I don't <br>> think it makes sense to do a preemptive strike on H_2 S, but rather <br>> find out if it will be a problem, then if it is, to deal with it. And <br>> of course whether it may be a problem depends on a number of factors. <br>> And remembering that the original question was about small-scale, farm <br>> or household digestion, of the millions of Chinese- and Indian-style <br>> digesters extant, I don't know of any significant use of scrubbing H_2 <br>> S that is used. Your thought appears to be the same since you say "In <br>> the SNV program they essentially use no filtration, and they really do <br>> not have issues."<br>> <br>> That said, using one of the methods mentioned by Henry of adding a <br>> source of the ferric ion, based on the figures he presents-- and they <br>> were minimal in his paper-- one would need 2 g Fe_2 O_3 /l of slurry. <br>> That can end up being quite a lot of material.<br>> <br>> But it is important to note that Henry does not assert that this is a <br>> well-tested dosage. In fact, according to his paper, he tried this <br>> technique only twice-- not with a range of dosages, in a series of <br>> digesters with varying amounts of sulfides, but only two times, once <br>> each in two test digesters. He says that<br>> <br>> "It can be seen that the amount of sulfide in the sludge in a<br>> digester is not a measure of the hydrogen sulfide in the<br>> digester gases. The sulfide may be tied, as in this case, with<br>> iron [DWH: i.e. often by adding it]. The iron content, of<br>> course, is not an exact figure. Any small bit of rust would<br>> have shown up too." <br>> <br>> <br>> So even the 2g/l figure is "more or less", and really this comes down <br>> to a sort of general guideline: if one has "too much" H2S in the <br>> biogas, then try adding "some" rust (or perhaps a bit of <br>> iron-containing soil, such as hematite) to the slurry.<br>> <br>> <br>> > My sense is that the sulpher and iron would actually work well as <br>> > micro nutrients, as both would be present in high concentrations. We <br>> > could make a powdered mixture with cal (lyme?) To both raise pH and <br>> > add the iron. Both materials are really cheap and effective in small <br>> > volumes. <br>> <br>> S (more likely) and Fe (less likely) might be micro-nutrients, but <br>> that would depend on the soil to which the effluent is being added. <br>> And even cheap materials, given that one would have to mix and add <br>> them, have a marginal cost in labor and complexity, so again either <br>> additive should earn its place following some degree of proof that it <br>> was actually needed, or sufficiently beneficial to warrant inclusion.<br>> <br>> <br>> > Regarding the biological filtration, I think the thesis you posted <br>> > talks about running the gas through a drier mix of cow manure. <br>> <br>> The cow manure filtration actually is mentioned in a different paper, <br>> although at the moment I don't have the time to track it down. The <br>> thesis I mentioned offers a lot of information that might be adapted <br>> to lower-tech biofiltration of H_2 S.<br>> <br>> <br>> > I have seen the industrial systems (RCM International a really <br>> > impressive model), but I have not been able work through the pumping <br>> > of substrate and air at a small scale.<br>> <br>> Any digester evolving biogas will provide enough pressure to cause the <br>> biogas to flow. The problem, as you indicate, would be getting enough <br>> but not too much air into the gas stream just before the point of <br>> exposure to whatever media was supporting the sulfur-loving bacteria.<br>> <br>> <br>> > Aside from engines, the question that SNV made me ask was: why <br>> > filter for small systems? If the combustion is complete the sulphur <br>> > becomes elemental, with a slight odor but not dangerous, or at least <br>> > how I understand it. We have never registered any dangerous sulphur <br>> > compositions in a kitchen. Thoughts? <br>> <br>> Actually when H_2 S is burned, it produces SO_2 , which is quite <br>> irritating (that concentrations of three to five PPM are readily <br>> detectable). Further, in the presence of water (and when the exhaust <br>> gases cool, water will be present), SO_2 combines to produce sulfurous <br>> acid (H_2 SO_3 ), which can corrode appliances, flues, and the like. I <br>> use sulfur to control gophers on my farm, for example, by putting some <br>> elemental sulfur in a run that I've dug up, then burning it into the <br>> burrow with a propane torch. Believe me, it's sufficiently deadly.<br>> <br>> I think, in sum, that the reason so little scrubbing is done is <br>> because few substrates contain sufficient sulfur to be of much <br>> concern, and those which do contain sulfur in some form (pig manure, <br>> for example) are generally digested at a pH sufficient to reduce the <br>> production of H_2 S (and/or there is sufficient ferric ion present-- <br>> widely available in soil and water-- to suppress the production of H_2 <br>> S) that it simply is not a problem in most situations.<br>> <br>> <br>> <br>> d.<br>> -- <br>> David William House<br>> "The Complete Biogas Handbook" |www.completebiogas.com|<br>> /Vahid Biogas/, an alternative energy consultancy |www.vahidbiogas.com<br>> <br>> |<br>> |<br>> "Make no search for water. But find thirst,<br>> And water from the very ground will burst."<br>> (Rumi, a Persian mystic poet, quoted in /Delight of Hearts/, p. 77)<br>> <br>> http://bahai.us/<br>> |<br>> -------------- next part --------------<br>> An HTML attachment was scrubbed...<br>> URL: <http://lists.bioenergylists.org/pipermail/digestion_lists.bioenergylists.org/attachments/20120926/1499eeb1/attachment-0001.html><br>> <br>> ------------------------------<br>> <br>> Message: 2<br>> Date: Thu, 27 Sep 2012 06:04:58 +0530<br>> From: Anand Karve <adkarve@gmail.com><br>> To: For Discussion of Anaerobic Digestion<br>> <digestion@lists.bioenergylists.org><br>> Subject: Re: [Digestion] Removal of hydrogen Sulphide from biogas<br>> Message-ID:<br>> <CACPy7ScV4KvtE5qWcm+Zy=-n2fvEq35Uaq3oneHJgDRsLXh5yQ@mail.gmail.com><br>> Content-Type: text/plain; charset="iso-8859-1"<br>> <br>> Dear Mr. Taiwo,<br>> passing biogas through a cylinder filled with iron filings or steel wool<br>> would remove the hydrogen sulphide. The iron filings would turn black by<br>> being converted into iron sulphide. Such blackened iron filings have to be<br>> periodically changed.<br>> Yours<br>> A.D.Karve<br>> <br>> On Tue, Sep 25, 2012 at 11:26 AM, Isiaka Taiwo<br>> <wealthofnature@hotmail.com>wrote:<br>> <br>> > Dear sir,<br>> ><br>> > I am an Electrical Engineer from Nigeria.<br>> ><br>> > I am working on biogas application on farm and low / middle class homes.<br>> ><br>> > My objective is to use biogas for cooking, running of small power<br>> > generators and lighting of gas lamps.<br>> ><br>> > I have accomplished the production of biogas from my biogas digester, and<br>> > I have burnt the gas and it gave blue flame.<br>> ><br>> > I have also converted a petrol generator to gas generator with a converter<br>> > I bought in country.<br>> ><br>> > I am delaying the test of the generator with biogas because of the<br>> > corrosive effect of the gas which I learnt can damage the generator. Also ,<br>> > I want to protect lives of the stakeholders as the hydrogen sulphide is<br>> > also poisonous.<br>> ><br>> > I am looking for simplest and easiest do it yourself (DIY) way(s) to<br>> > eliminate hydrogen sulphide from biogas and I think you can be of<br>> > assistance.<br>> ><br>> > I don't mind suggestion of suppliers of any ready made solution.<br>> ><br>> > Please , I am waiting for any assistance or useful information that will<br>> > help in realisation of my set objectives.<br>> ><br>> > Thanks for the anticipated assistance and supports.<br>> ><br>> ><br>> > Isiaka Taiwo<br>> > Sent from my BlackBerry wireless device from MTN<br>> ><br>> > _______________________________________________<br>> > Digestion mailing list<br>> ><br>> > to Send a Message to the list, use the email address<br>> > Digestion@bioenergylists.org<br>> ><br>> > to UNSUBSCRIBE or Change your List Settings use the web page<br>> ><br>> > http://lists.bioenergylists.org/mailman/listinfo/digestion_lists.bioenergylists.org<br>> ><br>> > for more information about digestion, see<br>> > Beginner's Guide to Biogas<br>> > http://www.adelaide.edu.au/biogas/<br>> > and the Biogas Wiki http://biogas.wikispaces.com/<br>> ><br>> ><br>> <br>> <br>> -- <br>> ***<br>> Dr. A.D. Karve<br>> Trustee & Founder President, Appropriate Rural Technology Institute (ARTI)<br>> -------------- next part --------------<br>> An HTML attachment was scrubbed...<br>> URL: <http://lists.bioenergylists.org/pipermail/digestion_lists.bioenergylists.org/attachments/20120927/e7034131/attachment-0001.html><br>> <br>> ------------------------------<br>> <br>> _______________________________________________<br>> Digestion mailing list<br>> <br>> to Send a Message to the list, use the email address<br>> Digestion@bioenergylists.org<br>> <br>> to UNSUBSCRIBE or Change your List Settings use the web page<br>> http://lists.bioenergylists.org/mailman/listinfo/digestion_lists.bioenergylists.org<br>> <br>> for more information about digestion, see<br>> Beginner's Guide to Biogas<br>> http://www.adelaide.edu.au/biogas/<br>> and the Biogas Wiki http://biogas.wikispaces.com/<br>> <br>> <br>> <br>> End of Digestion Digest, Vol 25, Issue 8<br>> ****************************************<br></div> </div></body>
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